# Model Evaluation

Evaluate the quality of the model using a handful of evaluation metrics.

## We'll cover the following

A residual value measures how much a regression line vertically misses a data point. Regression lines are the best fit for a set of data. We can think of the lines as averages; a few data points will fit the line, and others will miss. A residual plot has the residual values on the vertical axis, and the horizontal axis typically displays the independent variable.

## Residual scatterplot

The scatterplot below (residual values against `y_hat`

predictions) is helpful for understanding randomness.

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