You are responsible for… Completing this study guide (5 points per topic) Completing the Practice Problems (5 points per Studying hard and doing your best! 1: Sampling Techniques and Sources of Bias (Chapter: 4.1) Know and understand the difference between a population and sample How is each one measured (what do we use to measure them)? Why do we often measure samples instead of populations? Know the different types of bias and how to spot them in different situations Bias is anything that causes a sample to be not representative of the population of interest You must be able to articulate what the bias is, why it should be considered bias, and how it distorts the results from what they otherwise might be. What is the difference between sampling error and sampling bias? How can a sample size affect the validity of the sample? (this is related to sampling error rather than bias) Define the types of sampling bias (a bias in who was in the sample) Define the types of response bias (a bias in what the sample is saying) Undercoverage False Nonresponse bias trial
“Ranges from” “Goes from” Distorts Significant Substantial NOTE: It is okay to use words for their statistical definitions. Just use synonyms if you’re going to venture outside of that. If you aren’t sure what a word means, avoid using it!! to the script! Know how to phrase your analyses of the following (they are in your study guide). These phrasings help ensure you have covered all important aspects of the analysis in a clear and concise manner! Confidence intervals Confidence levels Interpreting p-values Analyzing or drawing conclusions about p-values of a regression line Interpreting r2 Randomization and a large sample size can solve most of life’s problems – they make for better, more accurate, and more reliable (unbiased) results DO NOT mix up the language of sampling and the language of experiments. For example, subjects of experiments are usually not randomly selected times that’s highly unethical). They are, however, randomly assigned to groups (at least they should be) If you use symbols, DEFINE what that symbol means. OR you can weave the context into your symbol Both ways are acceptable (although one is definitely quicker!) Symbols with definitions Symbols with context interwoven P(A ∩ B), where A represents being a girl and B represents being a senior P(Girl ∩ Senior) μ = 23, where μ represents the mean weight of the population of piglets (or true mean weight of piglets) μpiglets = 23 p1 > p2, where p1 represents the true proportion of adults who like snacks, and p2 represents the true proportion of children who like snacks padults > pchildren For sampling distributions, make sure you use (or ) for mean and (or ) for standard deviation IF YOU DON’T KNOW WHAT SYMBOL TO USE, DON’T USE A SYMBOL AT ALL!! There’s nothing wrong with writing out an answer in words. An incorrect symbol WILL get you docked. For inference problems (confidence intervals and significance test), LOOK for the statement “assume all conditions are met”. If it is not there, you had better check those conditions! Also be on the eye out for randomness – is it stated? And for 2-sample problems, is it stated for both samples? If you’re doing an interval or test, always provide the name of the procedure when you do it!
Remember, NEVER claim H0 or Ha are “true” or “false”. We “reject” or “fail to reject” based on the probability of getting a certain result by chance (that’s what significance tests are all about!) and we know that probability is NEVER a guarantee! BREATHE!! We’ve been working for this all year. You’ve got this! One wrong answer won’t kill you. Heck, just getting half of the questions right is almost guaranteed to be a 3! Don’t overthink – just do your best. GOOD LUCK!! Topic 13: Confidence Intervals and Significance Tests with Bivariate Data (Chapter: 12-we are not covering) A regression line is created using a _________________ of data. Confidence intervals and significance tests allow us to predict and test the ____________ slope of the relationship between the explanatory and response variables (x and y) You can also do this for y-intercept, but this is not something to worry about for the exam The AP exam will most likely ask you to use a ________________________ to make inference Remember, everything dealing with slope is in the row with the ______________________ (“constant” refers to the y-intercept) If you need to do them in the calculator… 1. Put all Xs in one list and Ys in another list 2. Go to LinRegInterval or LinRegT-Test, type in the inputs, and get your results!