Combining predetermined and measured assembly time techniques: Parameter estimation, regression and case study of fenestration industry

Time estimation is an important element of the effort evaluation process, which is indispensable along many phases of business development from bidding for the competitive contract to design and production phases. In particular, the time estimates are useful in the resource planning process, especially when the precision of the provided estimates is quantitatively characterised. We propose in this work an approach that combines the techniques developed within predetermined time methods (such as MODAPTS and MINIMOST) with the statistical techniques that use the real data (collected along the stopwatch time measurements). Our approach allows to obtain not only time estimates themselves, but also the confidence intervals for them. This information helps the practitioner to decide whether provided time estimates (coupled with accuracy parameters) meet his criteria. The proposed approach can be used in time estimations for the project containing several operations of different nature, and the application of our methodology is discussed in detail for the case of fenestration industry.