Question: Rules of thumb for minimum sample size for multiple regression


Question: Explain the difference between multiple regression and multivariate regression, with minimal use of symbols/math


Question: What algorithm should I use to detect anomalies on time-series?


Question: How to interpret coefficients in a Poisson regression?


Question: What is the difference between R functions prcomp and princomp?


Question: What is an ablation study? And is there a systematic way to perform it?


Question: Free resources for learning R


Question: On the importance of the i.i.d. assumption in statistical learning


Question: What is a kernel in plain English?


Question: Famous statistical wins and horror stories for teaching purposes


Question: How to obtain the p-value (check significance) of an effect in a lme4 mixed model?


Question: Why not approach classification through regression?


Question: What are disadvantages of using the lasso for variable selection for regression?


Question: Diagnostics for logistic regression?


Question: Shape of confidence interval for predicted values in linear regression


Question: Is there any good reason to use PCA instead of EFA? Also, can PCA be a substitute for factor analysis?


Question: What is the best way to remember the difference between sensitivity, specificity, precision, accuracy, and recall?


Question: Variable selection for predictive modeling really needed in 2016?


Question: What are the major philosophical, methodological, and terminological differences between econometrics and other statistical fields?


Question: How does a simple logistic regression model achieve a 92% classification accuracy on MNIST?


Question: What is global max pooling layer and what is its advantage over maxpooling layer?


Question: What is wrong with extrapolation?


Question: How exactly did statisticians agree to using (n-1) as the unbiased estimator for population variance without simulation?


Question: Bayes regression: how is it done in comparison to standard regression?


Question: Does no correlation imply no causality?


Question: Do not vote, one vote will not reverse election results. What is wrong with this reasoning?


Question: Impractical question: is it possible to find the regression line using a ruler and compass?


Question: How and why do normalization and feature scaling work?


Question: What are good initial weights in a neural network?


Question: Multivariate multiple regression in R


Question: Why does including latitude and longitude in a GAM account for spatial autocorrelation?


Question: Why do neural network researchers care about epochs?


Question: Whats so moment about moments of a probability distribution?


Question: How to split the dataset for cross validation, learning curve, and final evaluation?


Question: Practical questions on tuning Random Forests


Question: What is an intuitive explanation for how PCA turns from a geometric problem (with distances) to a linear algebra problem (with eigenvectors)?


Question: What is the intuition behind SVD?


Question: Model for predicting number of Youtube views of Gangnam Style


Question: What are some of the most common misconceptions about linear regression?


Question: Unified view on shrinkage: what is the relation (if any) between Steins paradox, ridge regression, and random effects in mixed models?


Question: What is the difference between discrete data and continuous data?


Question: What are good RMSE values?


Question: Good GUI for R suitable for a beginner wanting to learn programming in R?


Question: Where to cut a dendrogram?


Question: When to use generalized estimating equations vs. mixed effects models?


Question: Having a job in data-mining without a PhD


Question: Practical thoughts on explanatory vs. predictive modeling


Question: Complete substantive examples of reproducible research using R


Question: What method can be used to detect seasonality in data?


Question: Understanding ROC curve


Question: What is the difference between ZCA whitening and PCA whitening?


Question: Do all interactions terms need their individual terms in regression model?


Question: What makes the Gaussian kernel so magical for PCA, and also in general?


Question: How should tiny $p$-values be reported? (and why does R put a minimum on 2.22e-16?)


Question: A psychology journal banned p-values and confidence intervals; is it indeed wise to stop using them?


Question: Removing duplicated rows data frame in R


Question: How to actually plot a sample tree from randomForest::getTree()?


Question: Understanding stratified cross-validation


Question: How to tune hyperparameters of xgboost trees?


Question: Basic question about Fisher Information matrix and relationship to Hessian and standard errors


Question: What are some valuable Statistical Analysis open source projects?


Question: Is this the solution to the p-value problem?


Question: Covariance and independence?


Question: How to use Pearson correlation correctly with time series


Question: One-hot vs dummy encoding in Scikit-learn


Question: Proper way of using recurrent neural network for time series analysis


Question: How can adding a 2nd IV make the 1st IV significant?


Question: If A and B are correlated with C, why are A and B not necessarily correlated?


Question: Optimization when Cost Function Slow to Evaluate


Question: Is there any *mathematical* basis for the Bayesian vs frequentist debate?


Question: Whats the difference between feed-forward and recurrent neural networks?


Question: What are good basic statistics to use for ordinal data?


Question: Do the predictions of a Random Forest model have a prediction interval?


Question: Is PCA followed by a rotation (such as varimax) still PCA?


Question: What is the relationship between independent component analysis and factor analysis?


Question: What problem do shrinkage methods solve?


Question: How to normalize data between -1 and 1?


Question: What are i.i.d. random variables?


Question: How can an artificial neural network ANN, be used for unsupervised clustering?


Question: What is a saturated model?


Question: When are Log scales appropriate?


Question: ImageNet: what is top-1 and top-5 error rate?


Question: How is the minimum of a set of IID random variables distributed?


Question: Understanding the role of the discount factor in reinforcement learning


Question: Whats the difference between momentum based gradient descent and Nesterovs accelerated gradient descent?


Question: What is the difference between a neural network and a deep belief network?


Question: Assumptions regarding bootstrap estimates of uncertainty


Question: Look and you shall find (a correlation)


Question: What is a good, convincing example in which p-values are useful?


Question: Performance metrics to evaluate unsupervised learning


Question: Hold-out validation vs. cross-validation


Question: Statistics interview questions


Question: Central limit theorem for sample medians


Question: Intuition on the Kullback–Leibler (KL) Divergence


Question: Taleb and the Black Swan


Question: Where did the frequentist-Bayesian debate go?


Question: How to interpret F-measure values?


Question: How to simulate data that satisfy specific constraints such as having specific mean and standard deviation?


Question: Using principal component analysis (PCA) for feature selection


Question: Which pseudo-$R^2$ measure is the one to report for logistic regression (Cox & Snell or Nagelkerke)?


Question: Why bother with the dual problem when fitting SVM?


Question: Why is the Jeffreys prior useful?


Question: Intuitive explanation of Fisher Information and Cramer-Rao bound


Question: How to visualize what ANOVA does?


Question: Is the R language reliable for the field of economics?


Question: Standard errors for lasso prediction using R


Question: How can I help ensure testing data does not leak into training data?


Question: Why would parametric statistics ever be preferred over nonparametric?


Question: 40,000 neuroscience papers might be wrong


Question: References containing arguments against null hypothesis significance testing?


Question: How much to pay? A practical problem


Question: Regression with multiple dependent variables?


Question: Random Forest - How to handle overfitting


Question: What does orthogonal mean in the context of statistics?


Question: Why is sample standard deviation a biased estimator of $\sigma$?


Question: KL divergence between two multivariate Gaussians


Question: What is translation invariance in computer vision and convolutional neural network?


Question: Why is multicollinearity not checked in modern statistics/machine learning


Question: Variables are often adjusted (e.g. standardised) before making a model - when is this a good idea, and when is it a bad one?


Question: What is the difference between a partial likelihood, profile likelihood and marginal likelihood?


Question: Why is the square root transformation recommended for count data?


Question: Real-life examples of moving average processes


Question: Why do neural networks need so many training examples to perform?


Question: Is this chart showing the likelihood of a terrorist attack statistically useful?


Question: Maximum likelihood method vs. least squares method


Question: Why is it that natural log changes are percentage changes? What is about logs that makes this so?


Question: Why is logistic regression a linear classifier?


Question: Why is ANOVA equivalent to linear regression?


Question: Why only three partitions? (training, validation, test)


Question: Why does ridge estimate become better than OLS by adding a constant to the diagonal?


Question: What is the most surprising characterization of the Gaussian (normal) distribution?


Question: Criticism of Pearls theory of causality


Question: What is the difference between a nested and a non-nested model?


Question: Why do we minimize the negative likelihood if it is equivalent to maximization of the likelihood?


Question: Clustering with a distance matrix


Question: Does it make sense to add a quadratic term but not the linear term to a model?


Question: Derivation of closed form lasso solution


Question: Reduce Classification Probability Threshold


Question: Explain the xkcd jelly bean comic: What makes it funny?


Question: Do we need a global test before post hoc tests?


Question: How small a quantity should be added to x to avoid taking the log of zero?


Question: Efficient online linear regression


Question: Are bayesians slaves of the likelihood function?


Question: Who created the first standard normal table?


Question: List of situations where a Bayesian approach is simpler, more practical, or more convenient


Question: Why does collecting data until finding a significant result increase Type I error rate?


Question: Wald test for logistic regression


Question: Test if two binomial distributions are statistically different from each other


Question: What is the difference in Bayesian estimate and maximum likelihood estimate?


Question: Perform feature normalization before or within model validation?


Question: Is there a difference between controlling for and ignoring other variables in multiple regression?


Question: If we fail to reject the null hypothesis in a large study, isnt it evidence for the null?


Question: A more definitive discussion of variable selection


Question: What are the worst (commonly adopted) ideas/principles in statistics?


Question: How to statistically compare two time series?


Question: What is the effect of having correlated predictors in a multiple regression model?


Question: What is a contrast matrix?


Question: Software needed to scrape data from graph


Question: Examples of Bayesian and frequentist approach giving different answers


Question: Machine learning cookbook / reference card / cheatsheet?


Question: Brain teaser: How to generate 7 integers with equal probability using a biased coin that has a pr(head) = p?


Question: What does Scientists rise up against statistical significance mean? (Comment in Nature)


Question: Two-tailed tests... Im just not convinced. Whats the point?


Question: Is the hybrid between Fisher and Neyman-Pearson approaches to statistical testing really an incoherent mishmash?


Question: Interpreting Residual and Null Deviance in GLM R


Question: Variance of product of multiple independent random variables


Question: Is standardization needed before fitting logistic regression?


Question: Under what conditions should Likert scales be used as ordinal or interval data?


Question: Questions about how random effects are specified in lmer


Question: Should I use a categorical cross-entropy or binary cross-entropy loss for binary predictions?


Question: What is the difference between estimation and prediction?


Question: How to generate correlated random numbers (given means, variances and degree of correlation)?


Question: Does it ever make sense to treat categorical data as continuous?


Question: Why is tanh almost always better than sigmoid as an activation function?


Question: Which permutation test implementation in R to use instead of t-tests (paired and non-paired)?


Question: Binary classification with strongly unbalanced classes


Question: A generalization of the Law of Iterated Expectations


Question: Period detection of a generic time series


Question: What does the inverse of covariance matrix say about data? (Intuitively)


Question: Advanced statistics books recommendation


Question: What is so cool about de Finettis representation theorem?


Question: Why is the regularization term *added* to the cost function (instead of multiplied etc.)?


Question: Most famous statisticians


Question: A chart of daily cases of COVID-19 in a Russian region looks suspiciously level to me - is this so from the statistics viewpoint?


Question: Why is the validation accuracy fluctuating?


Question: How do you calculate the probability density function of the maximum of a sample of IID uniform random variables?


Question: How can I change the title of a legend in ggplot2?


Question: Data normalization and standardization in neural networks


Question: How does one interpret SVM feature weights?


Question: What is the relationship between a chi squared test and test of equal proportions?


Question: Why doesnt Random Forest handle missing values in predictors?


Question: Does 10 heads in a row increase the chance of the next toss being a tail?


Question: Difference between Random Forest and Extremely Randomized Trees


Question: Is adjusting p-values in a multiple regression for multiple comparisons a good idea?


Question: Is every covariance matrix positive definite?


Question: Measuring entropy/ information/ patterns of a 2d binary matrix


Question: Logistic regression in R resulted in perfect separation (Hauck-Donner phenomenon). Now what?


Question: Optimal number of folds in $K$-fold cross-validation: is leave-one-out CV always the best choice?


Question: How to derive variance-covariance matrix of coefficients in linear regression


Question: Is it meaningful to calculate Pearson or Spearman correlation between two Boolean vectors?


Question: How to calculate pseudo-$R^2$ from Rs logistic regression?


Question: Is it important to scale data before clustering?


Question: Comparing SVM and logistic regression


Question: Are mean normalization and feature scaling needed for k-means clustering?


Question: Why is expectation the same as the arithmetic mean?


Question: Best practice when analysing pre-post treatment-control designs


Question: What are the differences between epoch, batch, and minibatch?


Question: Clustering with K-Means and EM: how are they related?


Question: What is the variance of the weighted mixture of two gaussians?


Question: What are the shortcomings of the Mean Absolute Percentage Error (MAPE)?


Question: Are there cases where PCA is more suitable than t-SNE?


Question: How do I test that two continuous variables are independent?


Question: Choosing between LM and GLM for a log-transformed response variable


Question: What are disadvantages of state-space models and Kalman Filter for time-series modelling?


Question: Intuitive explanation of the bias-variance tradeoff?


Question: Why does shrinkage work?


Question: Examples where method of moments can beat maximum likelihood in small samples?


Question: Are all values within a 95% confidence interval equally likely?


Question: Industry vs Kaggle challenges. Is collecting more observations and having access to more variables more important than fancy modelling?


Question: Correlations between continuous and categorical (nominal) variables


Question: Manually Calculating P value from t-value in t-test


Question: Which activation function for output layer?


Question: Is chi-squared always a one-sided test?


Question: Which loss function is correct for logistic regression?


Question: What does standard deviation tell us in non-normal distribution


Question: How should one interpret the comparison of means from different sample sizes?


Question: Adam optimizer with exponential decay


Question: Neural networks vs support vector machines: are the second definitely superior?


Question: Recurrent vs Recursive Neural Networks: Which is better for NLP?


Question: Linear model with log-transformed response vs. generalized linear model with log link


Question: Box-Cox like transformation for independent variables?


Question: Bootstrap vs. jackknife


Question: Confidence interval for Bernoulli sampling


Question: Introduction to statistics for mathematicians


Question: Alternatives to logistic regression in R


Question: What is the intuition behind conditional Gaussian distributions?


Question: Resources for learning Markov chain and hidden Markov models


Question: How exactly does a random effects model in econometrics relate to mixed models outside of econometrics?


Question: Is ridge regression useless in high dimensions ($n \ll p$)? How can OLS fail to overfit?


Question: Interview question: If correlation doesnt imply causation, how do you detect causation?


Question: Why continue to teach and use hypothesis testing (when confidence intervals are available)?


Question: What is the difference between N and N-1 in calculating population variance?


Question: What does having constant variance in a linear regression model mean?


Question: Testing equality of coefficients from two different regressions


Question: Does the optimal number of trees in a random forest depend on the number of predictors?


Question: How to decide on the correct number of clusters?


Question: Difference between kernel and filter in CNN


Question: R libraries for deep learning


Question: How to interpret type I, type II, and type III ANOVA and MANOVA?


Question: How can a distribution have infinite mean and variance?


Question: What is the difference between a particle filter (sequential Monte Carlo) and a Kalman filter?


Question: How to apply standardization/normalization to train- and testset if prediction is the goal?


Question: What is the difference Cross-entropy and KL divergence?


Question: Are residuals predicted minus actual or actual minus predicted


Question: What is the objective function of PCA?


Question: Is it wrong to rephrase 1 in 80 deaths is caused by a car accident as 1 in 80 people die as a result of a car accident?


Question: Reference book for linear algebra applied to statistics?


Question: How do R and Python complement each other in data science?


Question: Statistics and causal inference?


Question: What are the breakthroughs in Statistics of the past 15 years?


Question: Are we exaggerating importance of model assumption and evaluation in an era when analyses are often carried out by laymen


Question: ANOVA assumption normality/normal distribution of residuals


Question: Mean absolute deviation vs. standard deviation


Question: Warning in R - Chi-squared approximation may be incorrect


Question: Standard error for the mean of a sample of binomial random variables


Question: Regression when the OLS residuals are not normally distributed


Question: How to determine best cutoff point and its confidence interval using ROC curve in R?


Question: What is the difference between GARCH and ARMA?


Question: Is random forest a boosting algorithm?


Question: Using deep learning for time series prediction


Question: How are regression, the t-test, and the ANOVA all versions of the general linear model?


Question: What are alternatives of Gradient Descent?


Question: Best PCA algorithm for huge number of features (>10K)?


Question: Book for reading before Elements of Statistical Learning?


Question: Why do Convolutional Neural Networks not use a Support Vector Machine to classify?


Question: When combining p-values, why not just averaging?


Question: What is the advantages of Wasserstein metric compared to Kullback-Leibler divergence?


Question: Is sampling relevant in the time of big data?


Question: Mathematical Statistics Videos


Question: How do we decide when a small sample is statistically significant or not?


Question: What are some examples of anachronistic practices in statistics?


Question: Backpropagation with Softmax / Cross Entropy


Question: Normalization vs. scaling


Question: Effect of switching response and explanatory variable in simple linear regression


Question: Graph for relationship between two ordinal variables


Question: Training a decision tree against unbalanced data


Question: A/B tests: z-test vs t-test vs chi square vs fisher exact test


Question: What is a difference between random effects-, fixed effects- and marginal model?


Question: Random forest computing time in R


Question: Why sigmoid function instead of anything else?


Question: Multivariate linear regression vs neural network?


Question: Standard deviation of standard deviation


Question: Practical hyperparameter optimization: Random vs. grid search


Question: Is the COVID-19 pandemic curve a Gaussian curve?


Question: Why on average does each bootstrap sample contain roughly two thirds of observations?


Question: Can a random forest be used for feature selection in multiple linear regression?


Question: How to tell the probability of failure if there were no failures?


Question: Modern successor to Exploratory Data Analysis by Tukey?


Question: Who are frequentists?


Question: Do we have a problem of pity upvotes?


Question: How to derive the ridge regression solution?


Question: How large should the batch size be for stochastic gradient descent?


Question: What is the difference between NaN and NA?


Question: What is maxout in neural network?


Question: How to identify a bimodal distribution?


Question: Correct spelling (capitalization, italicization, hyphenation) of p-value?


Question: Apply word embeddings to entire document, to get a feature vector


Question: Pandas / Statsmodel / Scikit-learn


Question: Prediction interval for lmer() mixed effects model in R


Question: Recommended books on experiment design?


Question: Should I normalize word2vecs word vectors before using them?


Question: What is a good algorithm for estimating the median of a huge read-once data set?


Question: What should I do when my neural network doesnt generalize well?


Question: Is it possible to do time-series clustering based on curve shape?


Question: Why do we use Kullback-Leibler divergence rather than cross entropy in the t-SNE objective function?


Question: Data APIs/feeds available as packages in R


Question: Intuitive explanations of differences between Gradient Boosting Trees (GBM) & Adaboost


Question: Can someone explain the concept of exchangeability?


Question: Is it true that the percentile bootstrap should never be used?


Question: Machine Learning using Python


Question: Why do we care so much about normally distributed error terms (and homoskedasticity) in linear regression when we dont have to?


Question: Why are MA(q) time series models called moving averages?


Question: Visually interesting statistics concepts that are easy to explain


Question: Most confusing statistical terms


Question: R - QQPlot: how to see whether data are normally distributed


Question: Is it a good practice to always scale/normalize data for machine learning?


Question: How to visualize a fitted multiple regression model?


Question: Interpretation of log transformed predictor and/or response


Question: Replicating Statas robust option in R


Question: Obtaining predicted values (Y=1 or 0) from a logistic regression model fit


Question: Why is the sum of two random variables a convolution?


Question: F1/Dice-Score vs IoU


Question: Multinomial logistic regression vs one-vs-rest binary logistic regression


Question: Why downsample?


Question: Software for drawing bayesian networks (graphical models)


Question: Statistical inference when the sample is the population


Question: Class imbalance in Supervised Machine Learning


Question: What book is recommendable to start learning statistics using R at the same time?


Question: Is there any gold standard for modeling irregularly spaced time series?


Question: Interpreting QQplot - Is there any rule of thumb to decide for non-normality?


Question: What are the main theorems in Machine (Deep) Learning?


Question: Where does the misconception that Y must be normally distributed come from?


Question: Intuition behind why Steins paradox only applies in dimensions $\ge 3$


Question: Why is a Bayesian not allowed to look at the residuals?


Question: Excel as a statistics workbench


Question: Are all models useless? Is any exact model possible -- or useful?


Question: How to perform a test using R to see if data follows normal distribution


Question: How to read Cooks distance plots?


Question: Is there a test to determine whether GLM overdispersion is significant?


Question: What is the difference between a Normal and a Gaussian Distribution


Question: Linear kernel and non-linear kernel for support vector machine?


Question: Is there any difference between lm and glm for the gaussian family of glm?


Question: Cross-Entropy or Log Likelihood in Output layer


Question: Wont highly-correlated variables in random forest distort accuracy and feature-selection?


Question: Does anyone know any good open source software for visualizing data from database?


Question: Cost function of neural network is non-convex?


Question: Regression for an outcome (ratio or fraction) between 0 and 1


Question: How are propensity scores different from adding covariates in a regression, and when are they preferred to the latter?


Question: How to select a clustering method? How to validate a cluster solution (to warrant the method choice)?


Question: Why does the correlation coefficient between X and X-Y random variables tend to be 0.7


Question: Why do statisticians say a non-significant result means you cant reject the null as opposed to accepting the null hypothesis?


Question: Fast linear regression robust to outliers


Question: Consider the sum of $n$ uniform distributions on $[0,1]$, or $Z_n$. Why does the cusp in the PDF of $Z_n$ disappear for $n \geq 3$?


Question: Famous easy to understand examples of a confounding variable invalidating a study


Question: How are we defining reproducible research?


Question: What is a good resource on table design?


Question: Cumming (2008) claims that distribution of p-values obtained in replications depends only on the original p-value. How can it be true?


Question: Relationship between $R^2$ and correlation coefficient


Question: Logistic Regression: Scikit Learn vs Statsmodels


Question: Using lmer for repeated-measures linear mixed-effect model


Question: What is Deviance? (specifically in CART/rpart)


Question: If the t-test and the ANOVA for two groups are equivalent, why arent their assumptions equivalent?


Question: Neural Network: For Binary Classification use 1 or 2 output neurons?


Question: Cross Entropy vs. Sparse Cross Entropy: When to use one over the other


Question: How to simulate artificial data for logistic regression?


Question: Regularization methods for logistic regression


Question: What is the difference between the forward-backward and Viterbi algorithms?


Question: Percentage of overlapping regions of two normal distributions


Question: How to do logistic regression subset selection?


Question: How do I find peaks in a dataset?


Question: How does LSTM prevent the vanishing gradient problem?


Question: What algorithm is used in linear regression?


Question: Understanding almost all local minimum have very similar function value to the global optimum


Question: Why do my p-values differ between logistic regression output, chi-squared test, and the confidence interval for the OR?


Question: Understanding Naive Bayes


Question: What is your favorite data visualization blog?


Question: Statistical tests when sample size is 1


Question: Why is statistically significant not enough?


Question: Why does frequentist hypothesis testing become biased towards rejecting the null hypothesis with sufficiently large samples?


Question: A smaller dataset is better: Is this statement false in statistics? How to refute it properly?


Question: Different ways to write interaction terms in lm?


Question: Find expected value using CDF


Question: What is the proper usage of scale_pos_weight in xgboost for imbalanced datasets?


Question: Choosing the right linkage method for hierarchical clustering


Question: Is a sample covariance matrix always symmetric and positive definite?


Question: Difference between GradientDescentOptimizer and AdamOptimizer (TensorFlow)?


Question: CNN architectures for regression?


Question: Rule of thumb for number of bootstrap samples


Question: Logistic Regression - Error Term and its Distribution


Question: What is perplexity?


Question: Normality of dependent variable = normality of residuals?


Question: Is minimizing squared error equivalent to minimizing absolute error? Why squared error is more popular than the latter?


Question: Survival Analysis tools in Python


Question: Random forest assumptions


Question: Which has the heavier tail, lognormal or gamma?


Question: Are splines overfitting the data?


Question: Motivation for Kolmogorov distance between distributions


Question: How to determine whether or not the y-axis of a graph should start at zero?


Question: Is Amazons average rating misleading?


Question: Clarification on interpreting confidence intervals?


Question: Does correlation = 0.2 mean that there is an association in only 1 in 5 people?


Question: Eliciting priors from experts


Question: AIC,BIC,CIC,DIC,EIC,FIC,GIC,HIC,IIC --- Can I use them interchangeably?


Question: Logistic Regression in R (Odds Ratio)


Question: Logistic regression model does not converge


Question: How do I avoid overlapping labels in an R plot?


Question: What is difference-in-differences?


Question: Why would R return NA as a lm() coefficient?


Question: Derive Variance of regression coefficient in simple linear regression


Question: Why is median age a better statistic than mean age?


Question: Clustering a long list of strings (words) into similarity groups


Question: Suppression effect in regression: definition and visual explanation/depiction


Question: How to interpret error measures?


Question: What is the definition of a feature map (aka activation map) in a convolutional neural network?


Question: Dynamic Time Warping Clustering


Question: Regression: Transforming Variables


Question: How does the Adam method of stochastic gradient descent work?


Question: When conducting a t-test why would one prefer to assume (or test for) equal variances rather than always use a Welch approximation of the df?


Question: How does centering the data get rid of the intercept in regression and PCA?


Question: Can machine learning decode the SHA256 hashes?


Question: How are kernels applied to feature maps to produce other feature maps?


Question: What is the distribution of the Euclidean distance between two normally distributed random variables?


Question: Do we have to tune the number of trees in a random forest?


Question: Kullback–Leibler vs Kolmogorov-Smirnov distance


Question: Empirical justification for the one standard error rule when using cross-validation


Question: What can we say about population mean from a sample size of 1?


Question: How can I calculate $\int^{\infty}_{-\infty}\Phi\left(\frac{w-a}{b}\right)\phi(w)\,\mathrm dw$


Question: Is it possible to interpret the bootstrap from a Bayesian perspective?


Question: Pitfalls in time series analysis


Question: Where to start with statistics for an experienced developer


Question: Can simple linear regression be done without using plots and linear algebra?


Question: First R packages source code to study in preparation for writing own package


Question: What is residual standard error?


Question: What do endogeneity and exogeneity mean substantively?


Question: How to interpret Mean Decrease in Accuracy and Mean Decrease GINI in Random Forest models


Question: Why do we use ReLU in neural networks and how do we use it?


Question: Logistic regression: anova chi-square test vs. significance of coefficients (anova() vs summary() in R)


Question: Rank in R - descending order


Question: How do I test a nonlinear association?


Question: Online vs offline learning?


Question: Expected number of ratio of girls vs boys birth


Question: Best method for short time-series


Question: How to interpret coefficients from a polynomial model fit?


Question: What is the distribution of the sum of non i.i.d. gaussian variates?


Question: What is the difference between prediction and inference?


Question: Why zero correlation does not necessarily imply independence


Question: Does the sign of scores or of loadings in PCA or FA have a meaning? May I reverse the sign?


Question: How does rectilinear activation function solve the vanishing gradient problem in neural networks?


Question: PCA and the train/test split


Question: Bootstrap vs. permutation hypothesis testing


Question: Features for time series classification


Question: What is the difference between posterior and posterior predictive distribution?


Question: Why is polynomial regression considered a special case of multiple linear regression?


Question: Generic sum of Gamma random variables


Question: Optimized implementations of the Random Forest algorithm


Question: What are the cons of Bayesian analysis?


Question: Is it unusual for the MEAN to outperform ARIMA?


Question: Where does $\sqrt{n}$ come from in central limit theorem (CLT)?


Question: How does saddlepoint approximation work?


Question: Bayesian statistics tutorial


Question: Why would someone use a Bayesian approach with a noninformative improper prior instead of the classical approach?


Question: Choosing variables to include in a multiple linear regression model


Question: Interpretation of Rs output for binomial regression


Question: What references should be cited to support using 30 as a large enough sample size?


Question: Using R online - without installing it


Question: Difference between forecast and prediction?


Question: SVM, Overfitting, curse of dimensionality


Question: How to make a time series stationary?


Question: Why does correlation matrix need to be positive semi-definite and what does it mean to be or not to be positive semi-definite?


Question: How does centering make a difference in PCA (for SVD and eigen decomposition)?


Question: Prediction in Cox regression


Question: Importance of local response normalization in CNN


Question: Alternatives to one-way ANOVA for heteroskedastic data


Question: Understanding LSTM units vs. cells


Question: Neural Networks: weight change momentum and weight decay


Question: Probability distribution for different probabilities


Question: Are there any good movies involving mathematics or probability?


Question: Bayesian equivalent of two sample t-test?


Question: Empirical relationship between mean, median and mode


Question: Statistical models cheat sheet


Question: Confidence interval around binomial estimate of 0 or 1


Question: Taking the expectation of Taylor series (especially the remainder)


Question: Does the reciprocal of a probability represent anything?


Question: Why do people use p-values instead of computing probability of the model given data?


Question: Are CDFs more fundamental than PDFs?


Question: What is the root cause of the class imbalance problem?


Question: How well can multiple regression really control for covariates?


Question: Understanding regressions - the role of the model


Question: How to interpret and report eta squared / partial eta squared in statistically significant and non-significant analyses?


Question: What are the values p, d, q, in ARIMA?


Question: Negative values for AIC in General Mixed Model


Question: How to interpret mean of Silhouette plot?


Question: What is quasi-binomial distribution (in the context of GLM)?


Question: Would PCA work for boolean (binary) data types?


Question: Logistic regression vs. LDA as two-class classifiers


Question: Danger of setting all initial weights to zero in Backpropagation


Question: Why is there a difference between manually calculating a logistic regression 95% confidence interval, and using the confint() function in R?


Question: Poisson regression to estimate relative risk for binary outcomes


Question: How to do community detection in a weighted social network/graph?


Question: How is softmax_cross_entropy_with_logits different from softmax_cross_entropy_with_logits_v2?


Question: Is regression with L1 regularization the same as Lasso, and with L2 regularization the same as ridge regression? And how to write Lasso?


Question: Approximate order statistics for normal random variables


Question: Why is softmax output not a good uncertainty measure for Deep Learning models?


Question: When is a biased estimator preferable to unbiased one?


Question: Deriving Bellmans Equation in Reinforcement Learning


Question: What exactly is Big Data?


Question: Rigorous definition of an outlier?


Question: Variational inference versus MCMC: when to choose one over the other?


Question: Why dont linear regression assumptions matter in machine learning?


Question: Computing Cohens Kappa variance (and standard errors)


Question: Why is multiple comparison a problem?


Question: How to plot trends properly


Question: Compendium of cross-validation techniques


Question: How seriously should I think about the different philosophies of statistics?


Question: Debunking wrong CLT statement


Question: Reviewing statistics in papers


Question: How to interpret F- and p-value in ANOVA?


Question: How to interpret the output of the summary method for an lm object in R?


Question: Using LASSO from lars (or glmnet) package in R for variable selection


Question: Lift measure in data mining


Question: How to assess the similarity of two histograms?


Question: PP-plots vs. QQ-plots


Question: Measures of variable importance in random forests


Question: How can I test if given samples are taken from a Poisson distribution?


Question: Is it valid to include a baseline measure as control variable when testing the effect of an independent variable on change scores?


Question: What are the differences between hidden Markov models and neural networks?


Question: Tiny (real) datasets for giving examples in class?


Question: Bayesian vs frequentist Interpretations of Probability


Question: Intuitive difference between hidden Markov models and conditional random fields


Question: Why does inversion of a covariance matrix yield partial correlations between random variables?


Question: What is the difference between Metropolis-Hastings, Gibbs, Importance, and Rejection sampling?


Question: What is the difference between a loss function and an error function?


Question: Is machine learning less useful for understanding causality, thus less interesting for social science?


Question: OpenBugs vs. JAGS


Question: When to use simulations?


Question: Would a Bayesian admit that there is one fixed parameter value?


Question: Intuitive explanation for density of transformed variable?


Question: What is your favorite statistical graph?


Question: Statistics published in academic papers


Question: Why does increasing the sample size lower the (sampling) variance?


Question: What is the reason why we use natural logarithm (ln) rather than log to base 10 in specifying function in econometrics?


Question: Mean absolute percentage error (MAPE) in Scikit-learn


Question: How to interpret p-value of Kolmogorov-Smirnov test (python)?


Question: Negative values for AICc (corrected Akaike Information Criterion)


Question: what does the numbers in the classification report of sklearn mean?


Question: Softmax layer in a neural network


Question: What is the significance of logistic regression coefficients?


Question: What is the adjusted R-squared formula in lm in R and how should it be interpreted?


Question: Should covariates that are not statistically significant be kept in when creating a model?


Question: What is meant by weak learner?


Question: Explanation of min_child_weight in xgboost algorithm


Question: When will L1 regularization work better than L2 and vice versa?


Question: Why does Andrew Ng prefer to use SVD and not EIG of covariance matrix to do PCA?


Question: LDA vs word2vec


Question: What is the difference between conditional and unconditional quantile regression?


Question: PCA and Correspondence analysis in their relation to Biplot


Question: Who invented stochastic gradient descent?


Question: Were generative adversarial networks introduced by Jürgen Schmidhuber?


Question: What is the purpose of characteristic functions?


Question: Why are regression problems called regression problems?


Question: Why do we only see $L_1$ and $L_2$ regularization but not other norms?


Question: Neural network references (textbooks, online courses) for beginners


Question: When teaching statistics, use normal or Gaussian?


Question: Fake uniform random numbers: More evenly distributed than true uniform data


Question: How do I get people to take better care of data?


Question: What is the difference between a population and a sample?


Question: Random number-Set.seed(N) in R


Question: AIC guidelines in model selection


Question: Interpreting the residuals vs. fitted values plot for verifying the assumptions of a linear model


Question: Comparing two models using anova() function in R


Question: Difference between naive Bayes & multinomial naive Bayes


Question: How to calculate relative error when the true value is zero?


Question: How to interpret glmnet?


Question: How to quasi match two vectors of strings (in R)?


Question: R - Confused on Residual Terminology


Question: Multiple regression or partial correlation coefficient? And relations between the two


Question: Determining sample size necessary for bootstrap method / Proposed Method


Question: How to choose between ROC AUC and F1 score?


Question: When and how to use standardized explanatory variables in linear regression


Question: When should I balance classes in a training data set?


Question: Relative variable importance for Boosting


Question: Are pooling layers added before or after dropout layers?


Question: Hierarchical clustering with mixed type data - what distance/similarity to use?


Question: What are best practices in identifying interaction effects?


Question: Confidence interval for median


Question: How trustworthy are the confidence intervals for lmer objects through effects package?


Question: Why do I get a 100% accuracy decision tree?


Question: Understanding the parameters inside the Negative Binomial Distribution


Question: Gamma vs. lognormal distributions


Question: Time series clustering in R


Question: Are your chances of dying in a plane crash reduced if you fly direct?


Question: How often do you have to roll a 6-sided die to obtain every number at least once?


Question: Does the beta distribution have a conjugate prior?


Question: whether to rescale indicator / binary / dummy predictors for LASSO


Question: Differences between Bhattacharyya distance and KL divergence


Question: How to efficiently generate random positive-semidefinite correlation matrices?


Question: Correlation does not imply causation; but what about when one of the variables is time?


Question: The Monty Hall Problem - where does our intuition fail us?


Question: How do DAGs help to reduce bias in causal inference?


Question: How to calculate a confidence level for a Poisson distribution?


Question: How to interpret OOB and confusion matrix for random forest?


Question: Statistical test to tell whether two samples are pulled from the same population?


Question: Improve classification with many categorical variables


Question: How to sample from a normal distribution with known mean and variance using a conventional programming language?


Question: How can I test whether a random effect is significant?


Question: Test for bimodal distribution


Question: Dice-coefficient loss function vs cross-entropy


Question: How do you use the test dataset after cross-validation?


Question: What is the difference between finite and infinite variance


Question: How to present results of a Lasso using glmnet?


Question: K-fold vs. Monte Carlo cross-validation


Question: What is the difference between coefficient of determination and mean squared error?


Question: How are Random Forests not sensitive to outliers?


Question: how to weight KLD loss vs reconstruction loss in variational auto-encoder


Question: Gradient Boosting for Linear Regression - why does it not work?


Question: What does the term saturating nonlinearities mean?


Question: What is model identifiability?


Question: Manually calculated $R^2$ doesnt match up with randomForest() $R^2$ for testing new data


Question: What are posterior predictive checks and what makes them useful?


Question: Approximate $e$ using Monte Carlo Simulation


Question: Why is 600 out of 1000 more convincing than 6 out of 10?


Question: References for survival analysis


Question: Interpretation of p-value in hypothesis testing


Question: How to determine significant principal components using bootstrapping or Monte Carlo approach?


Question: Are there any good popular science book about statistics or machine learning?


Question: Is LSTM (Long Short-Term Memory) dead?


Question: Does statistical independence mean lack of causation?


Question: Good games for learning statistical thinking?


Question: Evidence for man-made global warming hits gold standard: how did they do this?


Question: What is the relationship between the mean squared error and the residual sum of squares function?


Question: How to perform two-sample t-tests in R by inputting sample statistics rather than the raw data?


Question: Mixed Effects Model with Nesting


Question: How does linear regression use the normal distribution?


Question: Variance of product of dependent variables


Question: What exactly is a Bayesian model?


Question: Area under Precision-Recall Curve (AUC of PR-curve) and Average Precision (AP)


Question: Detecting Outliers in Time Series (LS/AO/TC) using tsoutliers package in R. How to represent outliers in equation format?


Question: How do I fit a constrained regression in R so that coefficients total = 1?


Question: What exactly is the alpha in the Dirichlet distribution?


Question: Purpose of the link function in generalized linear model


Question: What is the meaning of a confidence interval taken from bootstrapped resamples?


Question: Why do naive Bayesian classifiers perform so well?


Question: How to find a good fit for semi-sinusoidal model in R?


Question: Ridge, lasso and elastic net


Question: How do you do bootstrapping with time series data?


Question: How to test hypothesis of no group differences?


Question: Why do we need multivariate regression (as opposed to a bunch of univariate regressions)?


Question: Simulation of logistic regression power analysis - designed experiments


Question: Was mathematics invented or discovered?


Question: Is guns dont kill people, people kill people a good argument?


Question: Why dont fair coin tosses add up? Or... is gamblers fallacy really valid?


Question: Am I morally obligated to pursue a career in medicine?


Question: What logical fallacy is If you dont like it, move!?


Question: How does one know one is not dreaming?


Question: What would it take in a book to convince a rational person that it had been written by or directly inspired by a god?


Question: Could cogito ergo sum possibly be false?


Question: Is Kurt Gödels Incompleteness Theorem a cheap trick?


Question: Is it immoral to download music illegally?


Question: Can you prove anything in philosophy?


Question: How can an uneducated but rational person differentiate between science and religion?


Question: Logical fallacy: X is bad, Y is worse, thus X is not bad


Question: Why is there something instead of nothing?


Question: Why is faith seen as a sign of weakness, instead of an unexplored land/opportunity?


Question: Does human life have innate value over that of other animals?


Question: Is the omniscient-omnipotent-omnipresent definition of God consistent?


Question: In which way does quantum mechanics disprove determinism?


Question: How will learning about philosophy impact real-life?


Question: What is the difference between metaphysics and ontology?


Question: Why is a lion not evil?


Question: Why does the universe obey scientific laws?


Question: Why arent creationism and natural science on the same intellectual level?


Question: Why do they say I am committing a fallacy when I am just insulting someone?


Question: How can one not believe in god as the root cause of the universe?


Question: Why is Ayn Rands Objectivism philosophy dismissed by academics?


Question: Does Pascals Wager contain any logical flaws or fallacies?


Question: What is the moral difference between abortion and infanticide?


Question: Is there an alternative to the scientific method?


Question: What are the major branches of philosophy?


Question: Why do I accept some inconsequential claims as obviously true without evidence? E.g. Most people dont like to be hit on the head with a hammer.


Question: Is Mathematics always correct?


Question: What are the ethical problems with flipping a coin to decide in the trolley problem?


Question: Do numbers exist independently from observers?


Question: Did Russell understand Gödels incompleteness theorems?


Question: Is there a term for the belief that if its legal, its moral?


Question: What basis do we have for certainty in current scientific theories?


Question: Does a negative claimant have a burden of proof?


Question: What fallacy in Pascals Wager allows replacing God with the devil?


Question: What is the difference between free-will and randomness and or non-determinism?


Question: How to get started with philosophy without getting overwhelmed quickly?


Question: What did David Hume mean when he said that reason is a slave to the passions?


Question: What are the ethics of having children today?


Question: Fallacy by Sherlock Holmes Eliminate the impossible, and what remains must be the truth


Question: What should philosophers know about math and natural sciences?


Question: Is circular reasoning always a fallacy?


Question: Is faith necessary for man to survive / why is existentialism valued if it is unsubstantiated?


Question: How can one rebut the argument that atheism is inherently immoral?


Question: What are the necessary conditions for an action to be regarded as a free choice?


Question: Does happiness motivate every action?


Question: How come nihilism is so popular today?


Question: Should I respect other peoples religions?


Question: Is it a fallacy, and if so which, to believe we are special because our existence on Earth seems improbable?


Question: Why do atheist euthanasia proponents consider nothingness preferable to suffering?


Question: Is it a fallacy if someone claims they need an explanation for every word of your argument to the point where they dont understand common terms?


Question: Why doesnt philosophy have higher standards for its arguments?


Question: Asserting that Atheism and Theism are both faith based positions


Question: Fundamental idea on proving Gods existence with science


Question: Why has the philosophy of Bishop Berkeley fallen out of favor in academic philosophy?


Question: How can one differentiate nonexistent entities?


Question: What should a rational person accept as a miracle?


Question: Was Socrates a fictional character invented by Plato?


Question: What would Kant do when two categorical imperatives conflict? Could he ever justify lying?


Question: What is the difference (if any) between not true and false?


Question: If I said I had $100 when asked, but I actually had $200, would I be lying by omission?


Question: Why are believers criticized so much for being anti-science when so many scientists are ... believers?


Question: Why is scientism philosophically wrong?


Question: Why do some people care so much about empirical truth?


Question: Why is the complex number an integral part of physical reality?


Question: Three statements that contradict each other


Question: What is the purpose of the universe?


Question: Where and how can I get started in contemporary philosophy?


Question: In what sense is atheism scientific?


Question: How did first-order logic come to be the dominant formal logic?


Question: Is there anything that is totally random?


Question: What are some good introductions to philosophy?


Question: Is atheism just another form of dogma?


Question: How does mathematics work?


Question: How is Gödels incompleteness theorem interpreted in intuitionistic logic?


Question: Does humanisms rejection of God necesitate relativism?


Question: What are the philosophical implications of Gödels First Incompleteness Theorem?


Question: To what extent do we choose our beliefs?


Question: Is First Order Logic (FOL) the only fundamental logic?


Question: Are Methodological Assumptions of StackExchange Fundamentally Flawed?


Question: What is the difference between Fact and Truth?


Question: Do fundamental concepts in physics have any logical basis?


Question: Why should I read about philosophy?


Question: What does it mean for a book or a theorist to be post-modernist as opposed to modernist?


Question: Are we living in a simulation? The evidence


Question: Since words are defined in terms of other words in dictionaries, leading to infinite loops, does it mean natural languages are meaningless?


Question: Does the no true Scotsman fallacy apply to anti Stalinist etc. communism?


Question: Is I cannot imagine a mechanism for X to happen, so X can never happen a named logical fallacy?


Question: What are/were the main criticisms of logical positivism?


Question: Was Robin Hoods point of view ethically sound?


Question: When is absence of evidence not evidence of absence?


Question: Is it possible for something to have no cause?


Question: Why does Dawkins think it is wrong to posit that a paragon of 100% morals could theoretically exist?


Question: Where is the weakness in the ontological proof for Gods existence?


Question: Being alive today: the most improbable coincidence?


Question: If the Bible contains circular reasoning, does it discredit it?


Question: Does hypocrisy invalidate an argument?


Question: Isnt the notion that everything will occur in an infinite timeline an example of the gamblers fallacy?


Question: Im being drafted to the military but I have the option to refuse (legally), would it be immoral for me to serve?


Question: What arguments would support a secular pro-life position?


Question: What are the major research programmes in contemporary logic?


Question: What are some arguments against violence?


Question: Isnt the existence of Hell inherently evil, and isnt God therefore evil in allowing Hell to exist?


Question: How can one argue against income inequality while defending achievement and expertise inequality - beyond invoking Rawls difference principle?


Question: Can time exist without change?


Question: Does the lack of randomness imply the lack of free will?


Question: Have professional philosophers contributed to other fields in the last 20 years?


Question: Why is Aristotles objection not considered a resolution to Zenos paradox?


Question: In what way(s) does popular New Atheism fail to be philosophical?


Question: Is the claim this coin is fair falsifiable?


Question: What are some works that apply an axiomatic method to something other than mathematics?


Question: What is the difference between a statement and a proposition?


Question: Is infinite regress of causation possible? Is infinite regress of causation necessary?


Question: What is modal logic for?


Question: What are the philosophical implications of category theory?


Question: Is mathematics founded on beliefs and assumptions?


Question: What is Philosophy?


Question: Are people capable of generating a random number?


Question: Whats so fallacious about the Slippery Slope Fallacy?


Question: Are there any philosophical arguments to disprove or weaken solipsism?


Question: Why do color TVs make black and white snow?


Question: Why do glass windows still exist? (Why havent they been replaced by plastics?)


Question: Why is kVA not the same as kW?


Question: Why do cars have mirrors for rear view rather than cameras?


Question: Are toasters really electrified inside of the slots?


Question: How was Volkswagen able to trick the lab pollution test?


Question: My customer wants to use my products to do something unsafe. What is my ethical obligation?


Question: Is it possible for a bicycle chainwheel to have a fractional number of teeth?


Question: Transmitting power over long distances what is better AC or DC?


Question: What is the purpose of these diversions in a natural gas line?


Question: Is it possible to build a perfectly spherical Prince Ruperts drop?


Question: What is the purpose of these “partially filled in” locomotive wheels?


Question: How fast does solid waste fall in vertical drain pipes?


Question: Why dig out and then fill in before building a large structure?


Question: Is it possible to pump a powder?


Question: What are the pros and cons of a traffic circle versus a traffic light intersection?


Question: Why are railroad tank cars bent in the middle?


Question: Is it possible to build an air compressor with no moving parts?


Question: How to quantify martial arts strikes?


Question: Why do hydraulic systems use special fluid - whats wrong with water?


Question: Which is Worse: Car vs. Car or Car vs. Wall?


Question: How can a piece of paper be shaped to guarantee it falls slower than a plain sheet of paper?


Question: Calculating pitch, yaw, and roll from mag, acc, and gyro data


Question: Why are engine blocks so robust apart from containing high pressure?


Question: How are increasingly accurate machines made?


Question: From an engineering point of view what are the downsides of a too accurate model?


Question: Why would you launch a large ship by dropping it sideways?


Question: Understanding required torque for a motor lifting a weight


Question: Why use steam instead of just hot air?


Question: Why are rear wheels not placed at the extreme rear of a bus?


Question: Why doesnt a lightning strike destroy the lightning rod?


Question: Why dont hydroelectric plants use cascades of turbines instead of single turbines?


Question: What is the purpose of these steps in rivers?


Question: Why exactly does a washer help distribute the stress around a bolt?


Question: Why do car wheels have holes?


Question: What is a reason that handlebars fit to a motorcycle and steering wheel fit to a car?


Question: How to know whether the flow is supersonic in a nozzle?


Question: Why not put servers in a refrigerator?


Question: How do engineers really use numerical simulation?


Question: How much can Protactinium degrade the efficiency of the Thorium fuel cycle?


Question: How does width and thickness affect the stiffness of steel plate?


Question: Would it make sense to have a 12V lighting circuit in a house?


Question: How to make smoke for a small wind tunnel?


Question: Why does it take so long to restart a nuclear power plant?


Question: Why would a train automatically derail if a signal is passed at danger?


Question: Why did steam locomotives not transfer power by cogwheels?


Question: What makes suspension bridges unsuitable for railways?


Question: Why do cars turn by turning the front wheel?


Question: Does a roadway bridge experience more load when vehicles are parked or when they are moving?


Question: How does turning off electric appliances save energy


Question: Why are earthfills fully covered in concrete where they join bridges?


Question: Why does the Channel Tunnel enter the ground around 10 km from the coast?


Question: Sizing a pressure safety valve for two-phase flow


Question: Whats wrong with transporting a refrigerator on its side?


Question: How to stop water flow in a siphon?


Question: Windmills in empty fields. Why no trees?


Question: What is the purpose of building foundations?


Question: Why are truss bridges the way they are?


Question: How does a traffic light sense the proximity of vehicles?


Question: What are the engineering principles for a train to get electricity from the railway


Question: Is it structurally sound to cut an I beam to a T on one end?


Question: What are the major differences between Engineering degrees and Engineering Technology degrees in terms of employability?


Question: Pound-force (lbf) vs Pound-mass (lbm)


Question: Effective ways to drive a single shaft with multiple motors?


Question: What material is used to hold molten iron in a furnace?


Question: What is the most efficient means of warming a building with a high ceiling?


Question: Why does the microwave plate start in a random direction?


Question: Why do oil tankers heat crude oil?


Question: Why dont refrigerators have parts outdoors?


Question: How does measurement uncertainty combine with tolerances?


Question: How many train passes can railway tracks endure?


Question: How can I measure correctly with a ruler?


Question: Why doesnt epoxy stick to silicone?


Question: How are passive houses made in very hot regions (like Saudi Arabia)?


Question: How to design a house to be cooled passively?


Question: Fracture patterns in tempered glass


Question: Meshing of complex geometrical domains


Question: How can a storm drop 40 inches (1 metre) of rain?


Question: Impossible or improbable? Hurricane crossing the equator


Question: What place on Earth is closest to the Sun?


Question: Are there any saltwater rivers on Earth?


Question: Why does lightning strike from the ground-up?


Question: How many trees would I have to plant to solve Global Warming?


Question: How much oil is created each year?


Question: What started the US Dust Bowl of the 1930s, and could it happen again?


Question: Why is the pond in my backyard not frozen when it is -15 °C (5 °F) outside?


Question: How do greenhouse gases let heat in, but not let it out?


Question: Why do snowflakes form into hexagonal structures?


Question: Are Richter-magnitude 10 earthquakes possible?


Question: (How long) would Earths atmosphere last without a global magnetic field?


Question: Farthest point from the center of the Earth


Question: Are there any uncharted waters left on earth?


Question: How is the mass of the Earth determined?


Question: How its possible to measure temperature 2000 years ago with such precision?


Question: What would be the temperature of earth if there was no atmosphere?


Question: CO₂ level is high enough that it reduces cognitive ability. Isnt that a reason to worry?


Question: What does a mm of rain mean?


Question: Why do the Siberian methane craters have smooth vertical walls?


Question: How high must one be for the curvature of the earth to be visible to the eye?


Question: Why is Earths inner core solid?


Question: Is climate change a vicious circle?


Question: Is the sea level rise unusual?


Question: Does gravity increase the closer to the core you get?


Question: How do we know the asteroids formed at the same time as earth?


Question: Similarities between grand circulation solvers and mantle convection solvers


Question: Why is Earths age given by dating meteorites rather than its own rocks?


Question: How can we determine the size and composition of Earths inner core?


Question: Is there any river that does not discharge into larger body of water?


Question: How does anthropogenic heating affect global warming?


Question: How would plate tectonics differ if Earth had no water?


Question: Why do felsic materials have lower melting points than mafic?


Question: How and why did the oceans form on Earth but not on other planets?


Question: Is it true that earthquakes are not felt in a cave?


Question: Why does Coriolis determine the rotation direction of a cyclone but not my drain?


Question: What factors determine the number of Hadley cells for a planet?


Question: How much of the current global warming is due to human influence?


Question: Why is Earths outer-core liquid?


Question: Why does the salt in the oceans not sink to the bottom?


Question: At what humidity does it start to rain?


Question: Is it possible for rivers to freeze completely and stop flowing?


Question: Where on Earth is the magnetic field intensity stronger?


Question: Global warming - why doesn´t mankind collect heat (thermal energy) and turn it into electricity or send it to space?


Question: How would an icicle grow upwards?


Question: Is this XKCD comic an accurate timeline of the earths average temperature?


Question: How do weather models work?


Question: Is earthquake prediction possible?


Question: What is the status of the Raymo & Ruddiman idea that Tibet cooled the Earth?


Question: What are deconvolutional layers?


Question: How to set class weights for imbalanced classes in Keras?


Question: Micro Average vs Macro average Performance in a Multiclass classification setting


Question: Whats the difference between fit and fit_transform in scikit-learn models?


Question: Publicly Available Datasets


Question: K-Means clustering for mixed numeric and categorical data


Question: What is the dying ReLU problem in neural networks?


Question: Difference between isna() and isnull() in pandas


Question: How to draw Deep learning network architecture diagrams?


Question: When to use One Hot Encoding vs LabelEncoder vs DictVectorizor?


Question: When to use GRU over LSTM?


Question: Best python library for neural networks


Question: The cross-entropy error function in neural networks


Question: Train/Test/Validation Set Splitting in Sklearn


Question: How do you visualize neural network architectures?


Question: Python vs R for machine learning


Question: Why do people prefer Pandas to SQL?


Question: How to get correlation between two categorical variable and a categorical variable and continuous variable?


Question: SVM using scikit learn runs endlessly and never completes execution


Question: Choosing a learning rate


Question: Training an RNN with examples of different lengths in Keras


Question: Why do cost functions use the square error?


Question: When should I use Gini Impurity as opposed to Information Gain (Entropy)?


Question: Backprop Through Max-Pooling Layers?


Question: How big is big data?


Question: Advantages of AUC vs standard accuracy


Question: Time series prediction using ARIMA vs LSTM


Question: ValueError: Input contains NaN, infinity or a value too large for dtype(float32)


Question: How are 1x1 convolutions the same as a fully connected layer?


Question: strings as features in decision tree/random forest


Question: When to use (He or Glorot) normal initialization over uniform init? And what are its effects with Batch Normalization?


Question: Data scientist vs machine learning engineer


Question: Open source Anomaly Detection in Python


Question: In supervised learning, why is it bad to have correlated features?


Question: Convert a list of lists into a Pandas Dataframe


Question: Are Support Vector Machines still considered state of the art in their niche?


Question: What is dimensionality reduction? What is the difference between feature selection and extraction?


Question: What is the positional encoding in the transformer model?


Question: When is a Model Underfitted?


Question: Cosine similarity versus dot product as distance metrics


Question: What is the difference between equivariant to translation and invariant to translation


Question: Cross-entropy loss explanation


Question: GBM vs XGBOOST? Key differences?


Question: Clustering geo location coordinates (lat,long pairs)


Question: Adding Features To Time Series Model LSTM


Question: Tools and protocol for reproducible data science using Python


Question: RNN vs CNN at a high level


Question: Machine learning - features engineering from date/time data


Question: Why mini batch size is better than one single batch with all training data?


Question: Latent Dirichlet Allocation vs Hierarchical Dirichlet Process


Question: Neural networks: which cost function to use?


Question: Why do internet companies prefer Java/Python for data scientist job?


Question: How to clone Python working environment on another machine?


Question: What is the difference between Gradient Descent and Stochastic Gradient Descent?


Question: Does batch_size in Keras have any effects in results quality?


Question: How to fight underfitting in a deep neural net


Question: Is there any domain where Bayesian Networks outperform neural networks?


Question: IDE alternatives for R programming (RStudio, IntelliJ IDEA, Eclipse, Visual Studio)


Question: Number of parameters in an LSTM model


Question: What is the difference between LeakyReLU and PReLU?


Question: Why Is Overfitting Bad in Machine Learning?


Question: Should I go for a balanced dataset or a representative dataset?


Question: How to set batch_size, steps_per epoch, and validation steps?


Question: Should a model be re-trained if new observations are available?


Question: Does scikit-learn have a forward selection/stepwise regression algorithm?


Question: How to deal with version control of large amounts of (binary) data


Question: Is the R language suitable for Big Data


Question: What is the Q function and what is the V function in reinforcement learning?


Question: Sparse_categorical_crossentropy vs categorical_crossentropy (keras, accuracy)


Question: What is the use of torch.no_grad in pytorch?


Question: Why should the data be shuffled for machine learning tasks


Question: How to get accuracy, F1, precision and recall, for a keras model?


Question: In softmax classifier, why use exp function to do normalization?


Question: How to interpret the output of XGBoost importance?


Question: How do subsequent convolution layers work?


Question: Understanding predict_proba from MultiOutputClassifier


Question: Data Science in C (or C++)


Question: How much of data wrangling is a data scientists job?


Question: Deep Learning vs gradient boosting: When to use what?


Question: How do I compare columns in different data frames?


Question: Opening a 20GB file for analysis with pandas


Question: How to force weights to be non-negative in Linear regression


Question: How can I transform names in a confidential data set to make it anonymous, but preserve some of the characteristics of the names?


Question: train_test_split() error: Found input variables with inconsistent numbers of samples


Question: What is experience replay and what are its benefits?


Question: How to prepare/augment images for neural network?


Question: What is Ground Truth


Question: Merging two different models in Keras


Question: Why not always use the ADAM optimization technique?


Question: Multi GPU in Keras


Question: Can machine learning algorithms predict sports scores or plays?


Question: Does XGBoost handle multicollinearity by itself?


Question: Do data scientists use Excel?


Question: Data science related funny quotes


Question: What is the difference between model hyperparameters and model parameters?


Question: Choosing between CPU and GPU for training a neural network


Question: Encoding features like month and hour as categorial or numeric?


Question: Why are Machine Learning models called black boxes?


Question: LightGBM vs XGBoost


Question: The difference between `Dense` and `TimeDistributedDense` of `Keras`


Question: What is the advantage of keeping batch size a power of 2?


Question: When to use what - Machine Learning


Question: Intuitive explanation of Noise Contrastive Estimation (NCE) loss?


Question: What loss function to use for imbalanced classes (using PyTorch)?


Question: Calculation and Visualization of Correlation Matrix with Pandas


Question: Calculating KL Divergence in Python


Question: How does Keras calculate accuracy?


Question: Are there free cloud services to train machine learning models?


Question: Does gradient descent always converge to an optimum?


Question: What is the difference between bootstrapping and cross-validation?


Question: Why is ReLU used as an activation function?


Question: Do I need to learn Hadoop to be a Data Scientist?


Question: Is it always better to use the whole dataset to train the final model?


Question: What are some standard ways of computing the distance between documents?


Question: StandardScaler before and after splitting data


Question: Difference between OrdinalEncoder and LabelEncoder


Question: What do you think of Data Science certifications?


Question: How to set the number of neurons and layers in neural networks


Question: When is precision more important over recall?


Question: Applications and differences for Jaccard similarity and Cosine Similarity


Question: What are the advantages of HDF compared to alternative formats?


Question: What would I prefer - an over-fitted model or a less accurate model?


Question: Organized processes to clean data


Question: How does the validation_split parameter of Keras fit function work?


Question: When to use Random Forest over SVM and vice versa?


Question: Why do we need XGBoost and Random Forest?


Question: How to do SVD and PCA with big data?


Question: Best practices to store Python machine learning models


Question: Quick guide into training highly imbalanced data sets


Question: Paper: Whats the difference between Layer Normalization, Recurrent Batch Normalization (2016), and Batch Normalized RNN (2015)?


Question: Do Random Forest overfit?


Question: Is it necessary to standardize your data before clustering?


Question: How to calculate mAP for detection task for the PASCAL VOC Challenge?


Question: Sentence similarity prediction


Question: What is the best Keras model for multi-class classification?


Question: Unbalanced multiclass data with XGBoost


Question: What is the meaning of The number of units in the LSTM cell?


Question: Why is xgboost so much faster than sklearn GradientBoostingClassifier?


Question: Meaning of latent features?


Question: Early stopping on validation loss or on accuracy?


Question: What is a good way to transform Cyclic Ordinal attributes?


Question: What are the use cases for Apache Spark vs Hadoop


Question: How to use the output of GridSearch?


Question: Hypertuning XGBoost parameters


Question: Should we apply normalization to test data as well?


Question: Guidelines for selecting an optimizer for training neural networks


Question: RNNs with multiple features


Question: Why use both validation set and test set?


Question: Neural Network parse string data?


Question: How to decide neural network architecture?


Question: Are there any tools for feature engineering?


Question: Gini coefficient vs Gini impurity - decision trees


Question: Using TensorFlow with Intel GPU


Question: What to set in steps_per_epoch in Keras fit_generator?


Question: Are there any rules for choosing the size of a mini-batch?


Question: What does Logits in machine learning mean?


Question: Why is gold golden?


Question: Why can we smell copper?


Question: Can an atom have more than 8 valence electrons? If not, why is 8 the limit?


Question: Why doesnt water burn?


Question: Is a negative pH level physically possible?


Question: Why is absolute zero unattainable?


Question: Is there a general consensus on the causes of the alpha-effect?


Question: How do you melt metals with super high melting points?


Question: Is it actually possible to dispose of a body with hydrofluoric acid?


Question: Is toothpaste solid or liquid?


Question: What is Bents rule?


Question: Why is the 2s orbital lower in energy than the 2p orbital when the electrons in 2s are usually farther from the nucleus?


Question: Does water really go bad after a couple of days?


Question: If nothing sticks to Teflon, how does Teflon stick to frying pans?


Question: Is it true that heavy water is not blue?


Question: Do all salts taste salty?


Question: Bonding in diatomic C2, a carbon-carbon quadruple bond?


Question: What causes the old book smell?


Question: Why would breathing pure oxygen be a bad idea?


Question: How do people know HCN smells like almonds?


Question: Ortho-effect in substituted aromatic acids and bases


Question: Could a magnet pull oxygen out of the air?


Question: How do organic chemistry mechanisms become accepted?


Question: Why do elements in columns 6 and 11 assume abnormal electron configurations?


Question: Why is it wrong to use the concept of hybridization for transition metal complexes?


Question: How does Walter White make pure crystal meth using a non-stereospecific reaction?


Question: Why does F replace the axial bond in PCl5?


Question: Why does pasta really boil over?


Question: How can one explain niobium’s weird electronic configuration?


Question: Why does shaking a match put the fire out?


Question: Why doesnt H₄O²⁺ exist?


Question: Is iron in the brown ring compound in a +1 oxidation state?


Question: Why add water first then acid?


Question: Why is FORTRAN so commonly used in computational chemistry?


Question: Striking examples where Kohn-Sham orbitals clearly have no physical meaning


Question: How do I figure out the hybridization of a particular atom in a molecule?


Question: Are diamonds really forever?


Question: Why do we write NH3?


Question: The last elements atomic number


Question: Positive or Negative Anode/Cathode in Electrolytic/Galvanic Cell


Question: Why do compounds like SF6 and SF4 exist but SH6 and SH4 dont?


Question: What makes banana bonds possible in diborane?


Question: Why do shampoo ingredient labels feature the term Aqua?


Question: What makes some metals melt at higher temperature?


Question: What is the pH of ice?


Question: Is carbon dioxide organic or inorganic?


Question: Why dont we explode after drinking water?


Question: Regioselectivity of acid-catalyzed ring-opening of epoxides


Question: How can I update a map/mesh and coordinates in a PyMol session file?


Question: Why is it important to use a salt bridge in a voltaic cell? Can a wire be used?


Question: Why does menthol (e.g. peppermint) feel cool to the tongue?


Question: Why isnt aluminium involved in biological processes?


Question: How does chloroform degrade nitrile gloves?


Question: Why does ice water get colder when salt is added?


Question: Why is an S-S bond stronger than an O-O bond?


Question: Unit of the equilibrium constant: contradiction of Bridgmans theorem?


Question: How can antibonding orbitals be more antibonding than bonding orbitals are bonding?


Question: Why doesnt frozen sugar solution taste sweet?


Question: What happens to a radioactive carbon dioxide molecule when its carbon-14 atom decays?


Question: Why does bond angle decrease in the order H2O, H2S, H2Se?


Question: Does oil break down condoms?


Question: Why does wood burn but not sugar?


Question: Why do the names of most chemical elements end with -um or -ium?


Question: Is there any substance thats a 4-4-4 on the NFPA diamond?


Question: Mechanism of arene side chain oxidation by permanganate


Question: Why is the recipe of Coca Cola still a secret?


Question: Why does nitration of N,N-dimethylaniline occur at the meta position?


Question: Fundamental forces behind covalent bonding


Question: Is buckminsterfullerene aromatic?


Question: What volume does one mole of an ideal gas occupy?


Question: Why does sulfur, but not oxygen, catenate?


Question: What is the reason for the exceptional stability of the cyclopropylmethyl carbocation?


Question: What is resonance, and are resonance structures real?


Question: Whats the biggest organic molecule that could have a smell?


Question: Why can we still breathe in valleys?


Question: Are the lone pairs in water equivalent?


Question: Difference between thermodynamic and kinetic stability


Question: How can carbon dioxide be converted into carbon and oxygen?


Question: Inductive effect of hydrogen isotopes


Question: Why does CaCO3 react with HCl, but not with H2SO4?


Question: Carbon atoms at the edge of a diamond


Question: Differences between phenols and alcohols


Question: How can I predict if a reaction will occur between any two (or more) substances?


Question: Is it safe to drink reboiled water?


Question: Does heavy water taste sweet?


Question: What is more acidic: D3O+ in D2O or H3O+ in H2O and why?


Question: Can an atom bond with more than 8 other atoms?


Question: The reason behind the steep rise in pH in the acid base titration curve


Question: Why does whipped cream use nitrous oxide instead of nitrogen gas?


Question: Why is methanes molecular formula conventionally CH₄, while water is H₂O (among others)?


Question: Why is the vanadium(3+) ion paramagnetic?


Question: Why do SN1 and SN2 reactions not occur at sp2 centres?


Question: Why can a diamond be broken using a hammer if its the hardest natural substance known?


Question: Why does cyclopropane react with bromine?


Question: Why do impurities lower the melting point of an isolated substance?


Question: What causes the rotting fish smell?


Question: Do molecules with bridges through rings exist?


Question: Do symmetric hydrogen bonds in neutral molecules exist?


Question: What is the inert pair effect?


Question: How to derive these general formulae for number of stereoisomers of a compound with a possible plane of symmetry?


Question: Is there ANY chemical that can destroy PTFE, or Teflon?


Question: How can the dipole moment of carbon monoxide be rationalised by molecular orbital theory?


Question: Can 100% covalent bonds exist?


Question: Which exotic salt can lower waters freezing point by 70 °C?


Question: How does ammonium nitrate explode on its own?


Question: Why is arsenous acid denoted H3AsO3?


Question: Why is fresh ice sticky?


Question: Five-pointed crown alkane C25H40: does it exist?


Question: Is Hexafluorocyclohexane the Most Polar Small Molecule?


Question: Why do we use helium in balloons?


Question: Choosing the right condenser


Question: Why is the bond angle H-P-H smaller than H-N-H?


Question: Why is BCl3 a monomer whereas AlCl3 exists as a dimer?


Question: What exactly is happening when sodium, potassium, or other alkali metal explodes in water?


Question: Relativistic effect: d-electrons in metallorganic complexes


Question: Why does carbon monoxide have a greater affinity for hemoglobin than oxygen?


Question: What is a non-classical carbocation?


Question: What is the difference between ∆G and ∆G°?


Question: Why super glue does not stick inside their own bottle?


Question: What do the prefixes meta, ortho, pyro mean in inorganic chemistry?


Question: Why is pyrimidine less basic than pyridine?


Question: Why does potassium react more violently with water than lithium?


Question: Generating neat orbitals/surfaces from molden/wfn-files


Question: How do I visualize an atom?


Question: DFT Functional Selection Criteria


Question: Difference between shells, subshells and orbitals


Question: Why does alcoholic KOH prefer elimination whereas aqueous KOH prefers substitution?


Question: Why do atoms generally become smaller as one moves left to right across a period?


Question: What is known about liquid carbon?


Question: Gibbs free energy-minimum or zero?


Question: Is methanol more acidic than water?


Question: IUPAC nomenclature: Smallest sum of locants?


Question: Why is chemistry unpredictable?


Question: A compound that absorbs all visible light


Question: Natural Bond Orbital analysis: Significance of stabilization energy determined by 2nd order perturbation


Question: Does any known substance ignite on cooling?


Question: IUPAC nomenclature for an interesting looking organic compound


Question: What are the maximum number of electrons in each shell?


Question: Chemistry behind Gales coffee maker in Breaking Bad


Question: A glass of water with ice-cubes in it. Wheres the water the coldest; at the top or bottom?


Question: What exactly is hydrogen bonding (and does it really need fluorine, oxygen, or nitrogen)?


Question: Splitting of multiplets in ¹H NMR spectra?


Question: What is actually the difference between valence bond theory and molecular orbital theory?


Question: Why isnt ethane used for cooking?


Question: Why are there two Hydrogen atoms on some periodic tables?


Question: Can hot food ever emit x-rays or gamma rays?


Question: What would follow in the series sigma, pi and delta bonds?


Question: Are metallic/ionic bonds weaker than covalent bonds?


Question: Why is gold unreactive when only one electron is in the outer shell?


Question: Is pyrene aromatic despite failing Hückels rule?


Question: Is density functional theory an ab initio method?


Question: Does O2 have a color in the gas phase


Question: Has anyone even taken a picture of a molecule to confirm the geometry predicted by theory?


Question: Why isnt chemically-strengthened glass made with potassium carbonate to begin with?


Question: May I treat units (e.g. joules, grams, etc.) in equations as variables?


Question: Stereoselectivity of dihydroxylation with osmium tetroxide


Question: Why is the letter J omitted in the spdf... sequence?


Question: Hypervalency and the octet rule


Question: Pauli exclusion principle and resonance


Question: Proper typography of NOx


Question: Synthesis Golf II: Erythronolide B


Question: Single-molecule magnet with electrically-controlled permeability: How does the Titan Shield from Deus Ex work?


Question: How do I extract cyanide from apple seeds?


Question: Tetrahedral or Square Planar


Question: Why is [PdCl4]2- square planar whereas [NiCl4]2- is tetrahedral?


Question: Acidity of substituted phenols


Question: Why cant Pd/C and H2 reduce both the alkene and carbonyl portions of α,β-unsaturated carbonyls?


Question: Why is the bond length of CO+ less than that of CO?


Question: Why do chemistry and physics have different sign convention in thermodynamics?


Question: Why dont the electrons move through the electrolyte (instead of the circuit) in a galvanic cell?


Question: Why is methanol toxic?


Question: Effect of drinking ultra-pure water


Question: Would it be possible to destroy gold?


Question: Middle row anomaly of the periodic table


Question: When is it true that more nodes equals higher energy?


Question: Soaps come in different colors, but why is soap lather always white?


Question: How much CO2 could you remove from the atmosphere with 2 trillion USD?


Question: Why are isotopes of hydrogen the only ones with special names?


Question: Is there an energy cost associated with flipping the spin of an electron?


Question: Synthesis Golf I: Sodium Fluvastatin


Question: Flammability (NFPA) - how is it defined?


Question: What would be the effect of the addition of an inert gas to a reaction at equilibrium?


Question: Whats the difference between a nucleophile and a base?


Question: Why does basicity of group 15 hydrides decrease down the group?


Question: Is the ammonium substituent (-NH3+) really meta-directing in electrophilic substitution?


Question: Where did amino acids get their one-letter codes?


Question: Realistic chemical spill accident in high school chemistry class


Question: What caused the flashes in the video footage of Chernobyl?


Question: How are poisons discovered? Does someone have to die/be poisoned from it first?


Question: Why does hyperconjugation help for ring cleavage?


Question: What do the different grades of chemicals mean?


Question: What are the meanings of dotted and wavy lines in structural formulas?


Question: Why does pyrite form cubic crystals?


Question: Why does burnt hair smell bad?


Question: What roles do neutrons play in an atom?


Question: Why does the unstabilised Wittig reaction selectively form cis alkenes?


Question: Relative stability of cis and trans cycloalkenes


Question: Are there non-transparent gases?


Question: What is the molecular structure of xenon hexafluoride?


Question: What makes ice slippery?


Question: What makes Gorilla Glass more durable with each generation?


Question: Why do transition elements make colored compounds?


Question: Difference between exothermic and exergonic


Question: What is the unit of pH?


Question: Why does the 3rd electron shell start filling up with scandium?


Question: What is the strongest acid?


Question: Why are there only 7 types of unit cells and 14 types of Bravais lattices?


Question: Melting and boiling point trend in Group II


Question: Why is -ethane in methane?


Question: What is the exchange interaction?


Question: Are graphite and hexagonal boron nitride aromatic


Question: Why dont gases escape Earths atmosphere?


Question: How to properly store acids at home?


Question: Is honey really a supersaturated solution? Does heating to un-crystalize redissolve it or melt it?


Question: d-orbital splittings in WS2 monolayer


Question: Imaginary Bonding Interactions


Question: What are angular and radial nodes?


Question: Is alcohol really a solution?


Question: Why are covalent bonds directional?


Question: What metals arent dissolved in/attacked by aqua regia?


Question: What is the pKa of the hydronium, or oxonium, ion (H3O+)?


Question: Carbon with 5 bonds?


Question: Microwaving a glass of water, what happens?


Question: Which is the densest gas known?


Question: Electrical conductivity of graphite


Question: Why are DCM and chloroform so resistant towards nucleophilic substitution?


Question: What substances do humans consume that are caloric but neither protein, carb, nor fat?


Question: Why does chocolate melt so easily?


Question: Is activated carbon classified as organic or inorganic?


Question: Why is the Vitamin B complex, a complex?


Question: Is stainless a bulk or a surface property of stainless steel?


Question: How do orbitals coexist with a nucleus?


Question: Is there radioactivity at absolute zero?


Question: How heavy should an element be, to be a Heavy Metal?


Question: How to name binary (inorganic) compounds given their chemical formula, and vice-versa?


Question: Why is −78 °C a magic temperature for organic reactions?


Question: Why is 1-ethylidene-4-methylcyclohexane chiral?


Question: How do non-polar substances dissolve in non-polar solvents?


Question: How do you separate enantiomers?


Question: Acid Accident Treatment


Question: Why are solids and liquids not included in the equilibrium constant? What about in a reaction rate calculation?


Question: Why do atoms want to have a full outer shell?


Question: What happens to gunpowder when it gets wet?


Question: Which carbocation is more stable, the ethyl- or 1-propyl-carbocation?


Question: Why is water the universal solvent?


Question: Why are noble gases stable


Question: Why isnt the American nickel magnetic?


Question: What are oxidation states used for?


Question: Can magnetic fields affect a chemical reaction?


Question: When a candle burns, why does the top of wick glow if bottom of flame is hottest?


Question: What properties of carbon dioxide make it a greenhouse gas?


Question: Why is cyclooctateraene shaped like a tub rather than a chair?


Question: What happens if you cool water in a container too small for it to freeze?


Question: Why is fluorine a gas, but lithium isnt?


Question: Do electrons have some volume, area or shape?


Question: Are the bonding orbitals in methane equivalent - photoelectron spectrum


Question: Why are there no cheap diamond equivalents?


Question: Why is heroin a more potent drug than morphine, despite having a similar structure?


Question: Unusual Friedel–Crafts alkylation with pivaloyl chloride


Question: Suggest methods and basis sets for a variety of systems


Question: How many molecules does it take to have a phase?


Question: Why is snow white?


Question: How do Quantum Software Packages Work?


Question: Whats a minimal yet chemically-meaningful kinetic system for an oscillating reaction?


Question: What makes a radical free?


Question: How does Palladium dissociate H₂ so easily?


Question: What is the difference between D and L configuration, and + and −?


Question: How much gold is there in our sun?


Question: How loud would the Sun be?


Question: Does the Sun rotate?


Question: How can there be 1,000 stellar ancestors before our Sun?


Question: Why is the discovery of merging neutron stars important?


Question: Why dont astronomers use meters to measure astronomical distances?


Question: Could the dinosaurs have seen the asteroid that killed them?


Question: Is the moon only 60 pixels?


Question: Why is only one side of the Moon visible from Earth?


Question: How does the Earth move in the sky as seen from the Moon?


Question: Why not take a picture of a closer black hole?


Question: Can gravitational waves pass through a black hole?


Question: Is it dark inside the Sun?


Question: Does the Milky Way move through space?


Question: Why is there a zig-zag in elemental abundances?


Question: If a massive object like Jupiter flew past the Earth how close would it need to come to pull people off of the surface?


Question: How many planets are there in this solar system?


Question: When will the Sun end all human life on Earth?


Question: Why is the asteroid belt shaped like a triangle?


Question: Would we have more than 8 minutes of light, if the Sun went out?


Question: If two black hole event horizons overlap (touch) can they ever separate again?


Question: Why hasnt the 9th Planet been detected already?


Question: What is the hottest thing in the universe?


Question: Where did TRAPPIST-1a go?


Question: If light has no mass, why is it affected by gravity?


Question: Why does Io cast a hard shadow on Jupiter, but the Moon casts a soft shadow on Earth?


Question: Why is moon light not the same color as sunlight?


Question: What would happen if an ice cube is left in space?


Question: Sun constantly converts mass into energy, will this cause its gravity to decrease?


Question: Is there any role today that would justify building a large single dish radio telescope to replace Arecibo?


Question: How powerful a telescope would allow me to view the astronauts aboard ISS do a space-walk?


Question: Is there a star over my head?


Question: Why has Venuss atmosphere not been stripped away by solar wind?


Question: How did Astronomers deduce that the Sun was not a ball of fire?


Question: Why does it take so long to transmit an image from New Horizons to Earth?


Question: Two species of dark matter?


Question: Does the Milky Way orbit around anything?


Question: If Earth is tilted, why is Polaris always above the same spot?


Question: Is it possible to achieve a stable lunarstationary orbit around the moon?


Question: Why is Mars cold?


Question: How can HD 140283 be older than the universe?


Question: Does matter accumulate just outside the event horizon of a black hole?


Question: Where does the Solar System end?


Question: What is in the center of the universe?


Question: Does the sun cross other spiral arms in its movement around the galaxys center?


Question: Why do Black Holes in the middle of galaxies not suck up the whole galaxy?


Question: How does neutron star collapse into black hole?


Question: How do we have photos of galaxies so far away?


Question: How old is the oldest light visible from Earth?


Question: Are photons aged?


Question: Why does the Sun have different day lengths, but not the gas giants?


Question: Why does gas form a star instead of a black hole?


Question: Why is Gaia operating around Earth orbit? Why not send it to Neptunes orbit?


Question: Why is our solar system tipped about 63° with respect to the plane of our galaxy?


Question: Are new stars less pure as generations go by?


Question: How are black holes found?


Question: Can the moon appear to be in any position in the sky?


Question: How do scientists know that the distant parts of the universe obey the physical laws exactly as we observe around us?


Question: Do all stars have an Oort cloud or is it a rare occurence?


Question: Why are we building larger land-based telescopes instead of launching larger ones into space?


Question: Is Earths moon the only one where a total eclipse of the sun covers the entire sun?


Question: Why are there uneven bright areas in this photo of black hole?


Question: How do we know that black holes are spinning?


Question: How large can a ball of water be without fusion starting?


Question: Closest star system to Alpha Centauri?


Question: How do we distinguish old craters from new ones on the Moon?


Question: How can comets have tails if theres no air resistance in space?


Question: How do I calculate the inclination of an object with an amateur telescope?


Question: Is it a coincidence that on the far side of the moon almost no seas are visible?


Question: 9th planet location?


Question: Why cant we see Saturns phases from earth?


Question: Why does the Moon appear gray when passing between the Sun and the Earth?


Question: Are there any stars that orbit perpendicular to the Milky Ways galactic plane?


Question: Why does Jupiter have so many moons?


Question: Why doesnt the moon twinkle?