Simple Linear Regression › Visualizing Simple Linear Regression

Michael BrenndoerferApril 7, 20253 min read
Machine Learning from ScratchAll chapters
Part 4 of 9Regression Models
Chapter 29Simple Linear Regression › Visualizing Simple Linear Regression
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Let's create visualizations that demonstrate the key concepts of simple linear regression in action. These plots will help you understand how we find a fitted line, what residuals represent, and how to assess whether a linear model is appropriate for your data.

The first plot shows the complete regression analysis with data points, the fitted line, and residual lines connecting each point to its prediction. This visualization helps you see how well the linear model captures the underlying relationship and provides a clear view of the prediction accuracy across different values of the predictor variable.

The second plot focuses specifically on the residuals, the differences between observed and predicted values, which is important for model validation and assumption checking. Randomly scattered residuals around zero with no clear patterns indicate a good model fit, while systematic patterns or trends in the residuals suggest that a linear model may not be appropriate for the data. This diagnostic plot is important for validating the assumptions underlying linear regression.

Out[5]:
Visualization
Scatter plot with regression line and residual lines.
Simple linear regression fit showing the relationship between x and y variables. The red line represents the fitted linear model, while gray dashed lines show the residuals (vertical distances between actual data points and the fitted line). This visualization helps assess how well the linear model captures the underlying relationship in the data.
Residual plot showing prediction errors.
Residual plot displaying the distribution of prediction errors around the fitted line. Each point shows the difference between observed and predicted values. For a good linear model, residuals should be randomly scattered around the zero line with no clear patterns. Systematic patterns or trends in this plot indicate that a linear model may not be appropriate for the data.