4. A computer software organization was encountering serious problems in predicting the manday requirements for implementing large-scale programming projects. As part of a study on how to improve predic- tions, the company asked 24 programmers to predict the number of man-days for a large project about to be undertaken. The program- mers were given full details about the specications for the project. The programmers were classied by type of experience and amount of experience, and after the project was completed the forecasting er- rors were obtained. The forecasting errors (man-days predicted minus actual mandays) were: Amount of Experience Type of Experience Under 2 years 2-5 years More than 5 year: Small-scale systems only 268 98 46 190 118 92 245 88 55 188 96 58 Large-scale systems 85 47 38 44 52 33 68 33 42 57 49 35 I DO NOT TRANSFORM the data for parts (a and b). (a) State the model you will use to analyze the effects of amount and type of experience on the forecasting error. (b) Test whether the factors have any main effects and whether they interact. Use a level of signicance of .05 for each test. Write your ANOVA table. Present all the condence intervals and summarize your results