Factor model of construction productivity

The factor model for evaluating the productivity of laborintensive construction activities is described. The theory underlying the model is presented. The model states that many factors cause disturbances to crew performance. If these can be quantified and discounted from actual productivity data, one is left with an ideal productivity curve, which can be used to forecast future performance. Methods for collecting and combining data from various projects are presented and illustrated using actual productivity data from three commercial construction projects. Insight into the validity of the factor model is demonstrated by considering the effect of temperature and relative humidity on productivity. Multiple regression techniques are used to mathematically explain approximately 40% of the variability in the daily productivity data. Other statistical parameters are also described. The results of the weather model are compared to similar relationships reported by other researchers. The relationship developed by the writers is consistent with those reported in the literature. The factor model and the methods used to develop the weather model appear to be valid because the discounted productivity curve has less variability than the original productivity data. Lastly, an example is presented that illustrates the way in which the impact of weather on productivity can be evaluated.