A manager of boiler drums wants to use regression analysis to predict the number of worker-hours needed to erect the drums in future projects. Consequently, data for 36 randomly selected boilers were collected. In addition to worker-hours (Y), the variables measured include boiler capacity, boiler design pressure, boiler type, and drum type. All of these measurements are listed in the file P10_27.xlsx.
Estimate an appropriate multiple regression model to predict the number of worker-hours needed to erect given boiler drums using all available explanatory variables. Which explanatory variables should be included in a final version of this regression model? Justify your choices.