A meta-analysis combines the results of several studies that address a set of related research hypotheses or evaluate a common measure of effect size, which are modeled using a form of meta-regression. The resulting overall average, when appropriately controlled for study characteristics, can be considered a meta-effect size, and is generally a more powerful estimate of the true effect size than that derived from a single study. Meta analyses are now commonly used in drug development to compare new agents with marketed agents to define critical Go/No-Go decision points. Such evaluations provide information on the dose response for marketed and test drugs and can be developed based on published data. PRI has experience developing these models.