Line of best fit
SAT glossary · Math
Definition
The linear model minimizing squared vertical distances to data points. On the test, produced by Desmos regression, not by hand; used for prediction and slope-interpretation items.
Line of best fit in plain English
A line of best fit is the single straight line that comes closest overall to a scattered set of data points — specifically, it's the line that makes the total squared vertical distance between the line and every data point as small as possible. You are not expected to calculate this by hand on this test; instead, you're expected to use a built-in tool (like Desmos's regression feature) to generate it automatically. Once you have it, the line gets used for two main jobs: predicting a value you don't have data for, and interpreting what the slope actually MEANS in real-world terms.
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