Realization of simulations for blinded internal pilot study based on web

Misspecification of the designing parameters in the planning of a controlled clinical trial may yield an underpowered or an overpowered study. Internal pilot study, a kind of adaptive design, has gained increased attention for its allowing for sample size adjustment, especially blinded sample size adjustment that do not affect the type I error rate. Several methods were proposed to implement internal pilot design in recent years and some software emerges to simulate or implement it. But most of the software is only running on a stand-alone terminal or Client/Server(C/S) mode. We develop a system to simulate it based on Browser/Server(B/S) mode and realized on web. It allows the web users to input corresponding parameters from the web browser such as Internet Explorer to make simulations. The system was constructed with generic database schema design method and coded with Microsoft Visual Basic and Active Server Pages (ASP) programming languages. Web users on internet can use the system to make blinded variance estimate, sample size adjustment and randomization test for internal pilot study. The application of the simulation is demonstrated through an example. Not only blinded sample size adjustment is implemented but also a randomization test is performed. With applications of blinding one-sample variance for sample size recalculation and randomization test, the type I error rate is also controlled successfully.