The Probability of Completion of Outdoor Work

Abstract

If an outdoor job were being planned in an area which never received precipitation, all facilities could be scheduled with assurance that work could proceed to completion without interruption because of precipitation. In practice, many an outdoor job has been scheduled, only to be delayed several times before actual completion. It would be useful to be able to estimate the probability of completing a job as scheduled. A mathematical model is developed which includes: (1) A scheduled beginning date, (2) An amount of precipitation in one day that would interrupt a job, (3) The number of days of ?drying out? time required, (4) The number of work days required. For a particular place and job, the problem is to estimate the probability that a run of dry days will occur during a particular period of time. This could be estimated by counting runs in a sample period, or computed by several methods. In this study probabilities were computed by an approximation technique which yielded estimates comparable to those from counts of actual runs. Probability estimates for different beginning dates and lengths of drying and work periods are presented.