12.104 Standard error of slope The formula for the standard error of the sample slope b is se = s>Σ1x - x22, where s is the residual standard deviation.

a. Show that the smaller the value of s, the more precisely b estimates b.

b. Explain why a small s occurs when the data points show little variability about the prediction equation.

c. Explain why the standard error of b decreases as the sample size increases and when the x values display more variability.