Panel studies measure the attitudes of a set number of respondents over time. A panel study is unique in that it can reveal both the net and gross changes in the dependent variable. Unlike one-shot or cross-sectional studies, panel studies provide longitudinal data on individuals and households, making them ideal for statistical analyses that seek to reveal a cause – effect relationship. Like all research techniques, however, panels have their downsides as well. While panel studies cost less than a comparable series of parallel but separate samples (there is only a one-time sampling cost), they are still expensive to conduct and take a long time before they can produce actionable information. Panel studies may be conducted FTF, CATI, or through mail. Regardless of the preferred method, due to problems with retention, we recommend our clients to start with a large sample.