papayaprofessorLv10

17 Oct 2022

Please use the accompanying Excel data set or accompanying Text file data set when completing the following exercise.

An article in the ACI Materials Journal (Vol. 84, 1987, pp. 213-216) describes several experiments investigating the rodding of concrete to remove trapped air. A 3-inch x 6-inch cylinder was used, and the number of times this rod was used is the design variable. The resulting compressive strength of the concrete specimen is the response. The data are shown in the following table.

(a) Is there any difference in compressive strength due to the rodding level? Use = 0.05.

     Calculate to 2 decimal places :                          _______

 

     Is there statistical evidence to say that rodding level affects compressive strength?  ______

 

(b) Find to 2 decimal places the P-value for the F-statistic computed in part (a).

 

     P-value = _______

 

(c) Analyze the following residual plots to determine model adequacy.

     Does the assumption of normality seem reasonable?                  ______

     Does there appear to be an outlier in the data?                          ______

     Does the assumption of constant variance seem reasonable?      ______