27. A screw manufacturer is interested in giving out data to his customers on the relation between nominal and actual lengths. The following results (in inches)

were observed.

(a) Estimate the regression coefficients.

(b) Estimate the variance involved in manufacturing a screw.

(c) For a large set of nominal 1-inch screws, find a 90 percent confidence interval for the average length.

(d) For a nominal 1-inch screw, find a 90 percent prediction interval for its actual length.

(e) Plot the standardized residuals.
(f ) Do the residuals in part

(e) indicate any flaw in the regression model?
(g) Determine the index of fit.

Transcribed Image Text:

Nominal x Actual y 141731 .262 .262 .245 .496 .512 .490 .743 .744 .751 .976 1.010 1.004 1.265 1.254 1.252 221712 1.498 1.518 1.504 1.738 1.759 1.750 2.005 1.992 1.992