# Let’s review

This is what we’ve covered so far:

Meta-analysis is the process of using statistical models to carefully combine the results of your studies

When averaging your study results, be sure to:

1. Calculate the difference between treatment outcomes within each study first.

2. Decide whether each study is estimating the same true effect (in which case you use a common effect model) or different true effects (in which case you use a random effects model).

3. Calculate the average result by weighting each study result by its precision (also known as inverse variance).

Let’s assume that you’ve worked with a statistician and combined all of your study results into a formula that follows these steps. Now what?