Dr. o'connor was interested in whether men and women differ in sexual attitudes. she found that more than 170 studies had already been published on this issue. using she combined the results of these studies and analyzed the data for overall trends.

The answer here is meta-analysis.
We can see here that Dr O'Connor is using meta-analysis because she is examining the 170 studies that have been done on the topic to find out the truth that lies behind theses similar studies. Meta-analysis in essence is a statistical analysis done on the results of the previous studies on a certain topic or in a certain field as it combines all of those findings to get an overall result.  

the answer is a meta-analysis
meta-analysis refers to a statistical technique which combined the result of several studies in order to identify a certain trend.
The purpose of meta-analysis is usually to solve controversial topics that often resulted in wide variation of study conclusions.