Problem 4 Some graphical and numerical information about the

Problem 4: Some graphical and numerical information about the relationship between pretest and posttest scores is provided below. (a) What is the equation of the linear regression model relating posttest and pretest scores? (b) Discuss what s, r2, and the residual plot tell you about this regression model.

Solution

(a) The equation:

Posttest = 17.897 +0.78301*Pretest

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(b)

s=12.55 which is the regression model standard error

R^2=55.8% which means that 55.8% of variance can be explained by the regression line.

Residual plot: There is no pattern. So this regression model is good fitted.