We consider in this demonstration the analysis of complex data-intensive applications. We focus on three classes of analytical questions that are important for application owners and users alike: Why was a result obtained? What would be the result if the application logic or database is modified in a particular way? How can one interact with the application to achieve a particular goal? Answering these questions efficiently is a fundamental step towards optimizing the application and its use. Noting that provenance was a key component in answering similar questions in the context of database queries, we have developed POLYTICS, a system that employs novel provenance-based solutions for these analytic questions for data-centric applications. We propose to demonstrate POLYTICS using an online bicycle shop application as an example, letting participants play the role of both analysts and users.