Programmer requirements. A computer software firm was encountering difficulties in fore- casting the programmer requirements for large-scale programming projects. As part of a study to remedy the difficulties, 24 programmers, classified into cqual groups by type of experi- ence (factor A) and amount of experience (factor B), were asked to predict the number of programmer-days required to complete a large project about to be initiated. After this project was completed, the prediction errors (actual minus predicted programmer-days) were deter- mined. The data on prediction errors follow. a. Obtain the fitted values for ANOVA model (19.23). b. Obtain the residuals. c. Obtain the analysis of variance table. Does any one source account for most of the total variability? Explain. d. Test whether or not the two factors interact; use a = 0.01. State the alternatives, decision rule, and conclusion. e. Test whether or not main effects for type of experience and years of experience are present. Use a = 0.01in each case and state the alternatives, decision rule, and conclusion. f. Estimate M23 with a 99 percent confidence interval. Interpret your interval estimate. g. Estimate D = M12 - H13 with a 99 percent confidence interval. Interpret your interval estimate. Factor A (type of experience) Small systems only Factor B (years of experience) J=2 J = 3 Under 5 5-under 10 10 or more 240 110 56 206 118 60 217 103 68 225 95 58 71 47 37 53 52 33 68 40 57 49 45 ia 2 Small and large systems 31 Programmer requirements. A computer software firm was encountering difficulties in fore- casting the programmer requirements for large-scale programming projects. As part of a study to remedy the difficulties, 24 programmers, classified into cqual groups by type of experi- ence (factor A) and amount of experience (factor B), were asked to predict the number of programmer-days required to complete a large project about to be initiated. After this project was completed, the prediction errors (actual minus predicted programmer-days) were deter- mined. The data on prediction errors follow. a. Obtain the fitted values for ANOVA model (19.23). b. Obtain the residuals. c. Obtain the analysis of variance table. Does any one source account for most of the total variability? Explain. d. Test whether or not the two factors interact; use a = 0.01. State the alternatives, decision rule, and conclusion. e. Test whether or not main effects for type of experience and years of experience are present. Use a = 0.01in each case and state the alternatives, decision rule, and conclusion. f. Estimate M23 with a 99 percent confidence interval. Interpret your interval estimate. g. Estimate D = M12 - H13 with a 99 percent confidence interval. Interpret your interval estimate. Factor A (type of experience) Small systems only Factor B (years of experience) J=2 J = 3 Under 5 5-under 10 10 or more 240 110 56 206 118 60 217 103 68 225 95 58 71 47 37 53 52 33 68 40 57 49 45 ia 2 Small and large systems 31