Answer to Module 1, Exercise 1k:

SS Error is the sum of the squared deviations of observed scores from the predicted scores. If SS Error is very small, every observed score is close to the predicted score, so the plot of every observed score is close to the regression line.

If SS Error is much smaller than SS Total, then the sum of deviations around the regression line is much smaller than the sum of deviations around the mean. Thus, the regression equation gives much more accurate predictions of scores than simply using the mean as the prediction for all scores. The plot would show a strong linear relationship between X and Y.

If SS Error is about the same size as SS Total, then the regression equation has not improved our prediction of Y scores. The regression line would be close to horizontal at the mean. The plot would not show any indication of a linear relationship between X and Y.

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