10. Quality Control A manufacturer recorded the number of defective items (y) produced on a given day by each of 10 machine operators and also recorded the average output per hour ( ) 1 x for each operator and the time in weeks from the last machine service (X₂ ) .

The printout that follows resulted when these data were analyzed using the MINITAB package using the model:

a. Interpret R2 and comment on the fit of the model.

b. Is there evidence to indicate that the model contributes significantly to the prediction of y at the a 5.01 level of significance?

c. What is the prediction equation relating ˆy and 1 x when 4 2 x 5 ?

d. Use the fitted prediction equation to predict the number of defective items produced for an operator whose average output per hour is 25 and whose machine was serviced 3 weeks ago.

e. What do the residual plots tell you about the validity of the regression assumptions?

Transcribed Image Text:

y x X 13 20 3.0 1 15 2.0 11 23 1.5 2 10 4.0 20 30 1.0 15 21 3.5 27 38 0 5 18 2.0 26 24 5.0 1 16 1.5