【正文】 enhance the evaluation and control of schedule performance. Weibull analysis is a mon method for failure analysis and reliability engineering used in a wide range of applications. In this paper, the applicability of Weibull analysis for evaluating and paring the reliability of the schedule performance of multiple projects is presented. The various steps in the analysis are discussed along with an example in which two projects are analyzed and pared. The authors conclude that Weibull analysis has several advantages and provides a relatively robust and effective method for construction managers to better control and monitor their projects. Construction projects are seldom ―onschedule‖ all the time. The amount of work performed on the project usually fluctuates from one period to the other. In fact, according to the ―80 / 20‖ rule. suggested by the 18th Century economist, Pareto 80% of the effort will be expended during 20% of the project duration. This creates a significant problem in trying to monitor the actual performance of the project schedule and specifically trying to decide whether or not the project can finish on time., the reliability of the project schedule performance .The earned value method EVM is often used as a project control technique to provide a quantitative measure of schedule performance. In the EVM, the schedule and cost performance indices C/SPI are used for constant monitoring of the project’s cost and schedule based on an original critical path method CPM schedule Chang 2021 . Unfortunately, CPM scheduling in general creates an unrealistic expectation regarding project schedule performance. Starting a project one day and expecting that the project will finish on an exact date some two or three years in the future is unrealistic. Therefore, there is a need to extend schedule analysis techniques, like the EVM, to provide means for probabilistically analyzing the schedule performance and measuring the risks involved. In other management domains like software projects and business management, tools from the area of reliability, availability, and maintainability RAM engineering are now used to predict and avoid sudden system failures . RAM engineering is emerging as the newest discipline in product development due to new accurate, quantitative methods. Weibull analysis is foremost among these tools . Weibull analysis is a widely used method in the field of manufacturing and industrial engineering. It has mainly served for simulating failure rates or lifetime of certain products. By using this particular analysis one can make predictions about product’s life, pare the reliability of peting product designs, and manage spare parts inventories to name a few mon industrial applications Dorner 1997, 1999 . The objective of this study is to discuss and present the applicability of Weibull analysis for evaluating schedule performance using cost and performance indices C/SPI and to provide construction 2 managers with an effective tool for stochastically evaluating the C/SPI. A number of probabilistic techniques were checked against the data using AndersonDar