Our intention is to provide a set of probability and nonprobability sample pairs that research teams can use to compare the methods developed for utilizing nonprobability samples, especially in situations where a companion probability sample is available. **Probability sample covers the universe - Nonprobability sample covers a subset** is a simulation design that mimics the setting of a common type of nonprobability sample: a sample from an opt-in online panel which covers part of the target population (universe), and the probability sample covers all the target population. Files for this simulation are in the *Simulation files* subfolder. A subfolder, *Papers*, is for research papers that use simulation files. As with most simulations, we are unable to recreate the real-world complexities that are present in practice. It is also the case that estimation methods that produce successful outcomes from the simulated samples, such as, reduced bias and good confidence interval coverage, may not actually produce such outcomes with real-world samples. However, we believe that the simulated samples will be of use in understanding the models developed for utilizing nonprobability samples, alone or in combination with a probability sample. The strengths and weaknesses of the models will be better understood. We also hope that there will be more opportunities to create and share additional simulated samples based on different assumptions. The more we can do to test and probe methods for utilizing nonprobability samples, the better we will be able to understand and evaluate estimates based on nonprobability samples.