Regression

A regression describes how much one value changes on average when another goes up by one. It places the line that fits best through the cloud of points. Group columns (for example field of study) enter as comparisons with a reference group: B is then the difference from that group.

Example: For each additional hour of sleep, concentration is 2.70 points higher on average (95% CI [0.14, 5.27]). But sleep explains only about 4% of the differences (R² = .04).

Caution: "Prediction" is a calculation term here, not a cause. Outside the measured values (here 5 to 9.5 hours), the line does not apply.