LuxDev DataScience Week one Assignments
Published: 2023-09-27 21:07:51

**Question 1)** 
Imagine you're working with Sprint, one of the biggest telecom companies in the USA. They're really keen on figuring out how many customers might decide to leave them in the coming months. Luckily, they've got a bunch of past data about when customers have left before, as well as info about who these customers are, what they've bought, and other things like that.

So, if you were in charge of predicting customer churn how would you go about using machine learning to make a good guess about which customers might leave? Like, what steps would you take to create a machine learning model that can predict if someone's going to leave or not?

**Solution**
    **Data Collection**: Gather historical data on customer churn from Sprint's databases. This data should include information about customers who have churned in the past, such as their demographics, usage patterns, billing information, customer service interactions, and any other relevant features. It's important to have a representative and diverse dataset that captures various customer characteristics.

    **Data Preprocessing**: Clean the collected data by handling missing values, outliers, and inconsistencies. Convert categorical variables into numerical representations using techniques like one-hot encoding or label encoding. Normalize numerical features to ensure they are on a similar scale.

    **Feature Engineering**: Analyze the available data and identify relevant features that may impact churn. This can involve creating new features or transforming existing ones. For example, you could derive features such as average monthly usage, tenure of the customer, or the number of customer service calls made.

    **Splitting the Data**: Split the preprocessed dataset into training and testing sets. The training set will be used to train the machine learning model, while the testing set will evaluate its performance.

    **Model Selection**: Choose an appropriate machine learning algorithm for churn prediction. Commonly used algorithms include logistic regression, decision trees, random forests, gradient boosting, or neural networks. The choice of algorithm will depend on the specific requirements, dataset size, and desired interpretability of the model.

    **Model Training**: Train the selected model using the training dataset. During training, the model learns the underlying patterns and relationships between the input features and the churn outcome.

    **Model Evaluation**: Evaluate the trained model's performance using the testing dataset. Common evaluation metrics for churn prediction include accuracy, precision, recall, F1 score, and area under the receiver operating characteristic curve (AUC-ROC). Assess the model's performance to ensure it generalizes well to unseen data.

    **Hyperparameter Tuning**: Fine-tune the model's hyperparameters to optimize its performance. This can be done using techniques like grid search or random search, where different combinations of hyperparameters are evaluated.

    **Model Deployment**: Once you have a satisfactory model, deploy it to make predictions on new, unseen customer data. The model can be integrated into Sprint's existing systems to generate churn predictions and aid in decision-making processes.

    **Monitoring and Iteration**: Continuously monitor the model's performance after deployment. As new data becomes available, retrain the model periodically to keep it up to date and maintain its predictive accuracy.

It's worth noting that the success of a churn prediction model relies heavily on the quality and relevance of the data collected, as well as the domain expertise and feature engineering applied. Regularly updating the model with fresh data will also help improve its accuracy over time.

common evaluation metrics used to assess the performance of a churn prediction model



    Accuracy: Accuracy measures the proportion of correctly predicted churn and non-churn instances over the total number of predictions. It provides an overall measure of the model's correctness.

    Precision: Precision calculates the proportion of true positive predictions (churned customers correctly identified) over the total number of positive predictions. It indicates the model's ability to avoid false positives, i.e., correctly identifying non-churned customers.

    Recall (Sensitivity or True Positive Rate): Recall measures the proportion of true positive predictions over the total number of actual churned customers. It shows the model's ability to identify all churned customers, avoiding false negatives.

    F1 Score: The F1 score is the harmonic mean of precision and recall. It provides a balanced measure of the model's performance by considering both precision and recall. It is useful when there is an imbalance between the number of churned and non-churned customers in the dataset.

    Specificity (True Negative Rate): Specificity calculates the proportion of true negative predictions (non-churned customers correctly identified) over the total number of actual non-churned customers. It indicates the model's ability to avoid false negatives.

    Area Under the Receiver Operating Characteristic Curve (AUC-ROC): The AUC-ROC metric evaluates the model's ability to discriminate between churned and non-churned customers across various classification thresholds. It measures the area under the curve plotted using the true positive rate (TPR) against the false positive rate (FPR). A higher AUC-ROC score indicates better model performance.

    Confusion Matrix: A confusion matrix provides a tabular representation of the model's predictions against the actual churned and non-churned instances. It shows the true positives, true negatives, false positives, and false negatives, allowing for a more detailed analysis of the model's performance.

When evaluating a churn prediction model, the choice of evaluation metrics will depend on the specific objectives, business requirements, and priorities of the telecom company, such as the cost associated with false positives and false negatives. It's also important to consider the context and potential impact of the model's predictions on business decisions and customer retention strategies.

**Calculating F1 score**
The F1 score is a single metric that combines precision and recall into a balanced measure of a model's performance. It is the harmonic mean of precision and recall, providing a way to assess a model's ability to achieve both high precision and high recall simultaneously.

The F1 score is calculated using the following formula:

F1 Score = 2 * (Precision * Recall) / (Precision + Recall)

Here's a breakdown of the components used in the formula:

    Precision: Precision is the proportion of true positive predictions (churned customers correctly identified) over the total number of positive predictions. It is calculated using the formula:

Precision = True Positives / (True Positives + False Positives)

    Recall: Recall, also known as sensitivity or true positive rate, is the proportion of true positive predictions over the total number of actual churned customers. It is calculated using the formula:

Recall = True Positives / (True Positives + False Negatives)

    F1 Score: The F1 score combines precision and recall by taking their harmonic mean. The harmonic mean gives more weight to lower values, making the F1 score lower when either precision or recall is low. It is calculated using the formula:

F1 Score = 2 * (Precision * Recall) / (Precision + Recall)

The F1 score ranges from 0 to 1, where 1 indicates perfect precision and recall, and 0 indicates poor performance in either precision or recall. By using the harmonic mean, the F1 score penalizes models that have a significant imbalance between precision and recall, ensuring a balanced assessment of the model's overall performance.

example:
Predicted
                 Churned  Not Churned
Actual Churned    150         50
Actual Not Churned  30        770
Using the confusion matrix, we can calculate the precision, recall, and F1 score as follows:

    Precision:
    Precision = True Positives / (True Positives + False Positives) = 150 / (150 + 30) = 0.833

    Recall:
    Recall = True Positives / (True Positives + False Negatives) = 150 / (150 + 50) = 0.75

    F1 Score:
    F1 Score = 2 * (Precision * Recall) / (Precision + Recall) = 2 * (0.833 * 0.75) / (0.833 + 0.75) = 0.789

In this example, the churn prediction model achieved a precision of 0.833, which means that out of all the customers predicted as churned, 83.3% of them were correctly identified as churned customers. The recall is 0.75, indicating that 75% of the actual churned customers were correctly identified by the model.

The F1 score, calculated as the harmonic mean of precision and recall, is 0.789. This metric provides a balanced assessment of the model's performance, taking into account both precision and recall. A higher F1 score indicates better overall performance in terms of correctly identifying churned customers while minimizing false positives and false negatives.

The F1 score is particularly useful when dealing with imbalanced datasets, where the number of churned and non-churned customers differs significantly. It provides a single metric that considers both false positives and false negatives, helping to evaluate model performance in scenarios where both types of errors have important consequences.

**Question 2).**
Let’s say you’re a Product Data Scientist at Instagram. How would you measure the success of the Instagram TV product?
**Solution**
As a Product Data Scientist at Instagram, measuring the success of the Instagram TV (IGTV) product would involve a combination of quantitative and qualitative metrics. Here are several key metrics and approaches that can be used:

    Usage Metrics: Monitoring usage metrics provides insights into how users are engaging with IGTV. Key metrics to consider include:
        Number of Views: Tracking the total number of views on IGTV videos provides an indication of user engagement and interest.
        Number of Users: Monitoring the number of unique users who engage with IGTV helps understand the reach and adoption of the product.
        Watch Time: Tracking the total watch time on IGTV videos indicates user engagement and the overall stickiness of the product.

    Retention Metrics: Assessing user retention is important for understanding the long-term success of IGTV. Metrics to consider include:
        User Retention Rate: Tracking the percentage of users who continue to engage with IGTV over time helps assess user loyalty and whether the product is retaining its user base.
        Churn Rate: Monitoring the rate at which users stop using IGTV provides insights into user dissatisfaction or disengagement.

    Content Metrics: Evaluating the quality and popularity of content on IGTV is crucial for its success. Metrics to consider include:
        Number of Content Creators: Tracking the number of creators actively producing content on IGTV indicates the platform's attractiveness to content creators.
        Engagement Metrics: Measuring metrics such as likes, comments, and shares on IGTV videos helps assess user interaction and engagement with the content.

    Monetization Metrics: If monetization is a goal for IGTV, the following metrics can be considered:
        Ad Revenue: Tracking the revenue generated through advertisements on IGTV helps evaluate its monetization potential.
        Conversion Metrics: If IGTV offers features like product tagging or influencer collaborations, tracking metrics such as click-through rates, conversions, and sales can provide insights into its effectiveness as a revenue-generating platform.

    User Feedback and Surveys: Gathering qualitative feedback from users through surveys, interviews, or social media listening provides valuable insights into user satisfaction, pain points, and suggestions for improvement.

    Competitive Analysis: Analyzing the performance and market share of IGTV compared to competitors in the video streaming space can provide context and help assess success relative to the industry.

It's important to establish specific goals and metrics aligned with the objectives of the IGTV product, taking into account user engagement, retention, content quality, and potential monetization opportunities. Regular monitoring and analysis of these metrics can help track the success of the IGTV product and guide data-driven decision-making for product enhancements and optimizations.