How Prof. Steve Gangestad successfully ran a complex longitudinal study with Prolific

Steve Gangestad is a Distinguished Professor Emeritus at the University of New Mexico’s Department of Psychology. His research explores factors that influence women’s sexual interests.

As part of a longitudinal research project, he used Prolific’s managed research service to help gather high-quality data for a challenging study.

The task

The goal of the research was to explore how cisgender women’s sexual interests are affected by the different stages of their menstrual cycle. 

Women are only conceptive for a few days during the cycle, although they can have, as Prof. Gangestad notes, “interest in sex throughout the entire cycle.” This doesn’t frequently happen in other mammals. Cisgender women, on average, will experience more sexual desire and interest when conceptive. But this still doesn’t explain what’s going on outside the cycle. 

Prof. Gangestad and his team want to learn more about why this happens and what non-conceptive sex is for. What influences women’s sexual interest when they’re both conceptive and non-conceptive? He hypothesized that these interests might not be something women are consciously aware of.

For this study, Prof. Gangestad and his team were looking to recruit women with long-term romantic partners. They wanted to find out: 

• If there are differences in how bonded women are to their partners. 
• Whether women who are less bonded have more sexual interest throughout the entirety of their cycle 
• If any patterns were replicated across the data.

The challenge

This study presented three key challenges. 

Specific participants had to be involved in the data set

When screening for female participants, Prof. Gangestad and the team had a strict set of criteria they wanted. This included:

• In a partnered relationship for over three months. 
• Naturally cycling - not using birth control, having unprotected sex, and not pregnant or breastfeeding.
• At least 18 years old but no more than 35.
• Has reasonably regular cycles.
• English-speaking.

Collecting data across an entire cycle

This was a short-term, longitudinal study. The team wanted to get a sampling of each woman’s initiation of sex and other variables across the entire cycle, over roughly 30 days - which isn’t easy to carry out.

Conducting a short-term, longitudinal study

This study would require running one study per day, every day, for 30 days. Studies like this aren’t easy to run - they take considerable effort to manage. Participants must stay committed and engaged throughout the study, which means constant communication between researchers and participants. You also have to carefully manage study release times to ensure as many participants as possible complete them.    

The solution

To overcome these challenges, Prof. Gangestad turned to Prolific’s managed research services. Andrew Gordon, Prolific’s Senior Research Consultant, quickly assessed the study's requirements and worked with the team to find a solution. 

The data would be collected using repeated measures, similar to a ‘daily diary.’ This allowed participant responses to be measured across the entire cycle. 

After an initial week-long screening questionnaire, the data collection process took just a month. 

Why Prolific?

Prof. Gangestad learned of the high-quality, qualitative data he could gather via Prolific, and its high participation retention rates. 

Watch the full video case study.

Other factors that influenced his choice included:

A ready-to-go data set

Many variables for the set criteria the team was looking for were already in Prolific’s pool of 200k+ participants. Prolific also made it easy to identify a subset, with built-in functionality to send screening questionnaires to ensure the team could find the right participants. Prof. Gangestad could recruit English-speaking participants from the UK and the USA; three-quarters of the sample came from the UK.

Gathering specific data

Participants were asked to complete an initial 30-minute questionnaire. This captured information about their relationship and when their last menstruation was so the team could see where they were in the cycle. This meant the team could access specific, accurate data.

They further screened the applicable participants based on this questionnaire. From this, they could get 30 consecutive days of survey data. This included daily reports on: 

• Whether they initiated sex with a partner in the last 24 hours.
• Whether their partner initiated sex.
• If they had an onset of menses. 

This helped identify where they were in their cycle, so the team had additional clarity on the data they were collecting.

Running the study in sync

Prolific enabled Prof. Gangestad and the team to run the study in sync. Participants filled out the daily questionnaires for 30 days, starting the same day. This provided high-quality data and made tracking participation rates and overall study progress easy.

The team initially planned a single research study. But because of the speed of data access, each day could be set up as a single, separate study.

An active sample

Prolific provided Prof. Gangestad and the team access to highly active participants in the study. They invited over 300 participants, 294 of whom completed the initial questionnaire, and at least 280 completed at least ten surveys. Although they weren’t required to participate in every survey, the average was 27 out of 30 surveys completed.

The team ran a follow-up questionnaire after the survey data was collected.

The study was designed to gather extra information from participants at the onset of their next menses. This was variable, so they had to stagger the release of this final survey by guessing when the onset of their next menses would be and releasing the survey accordingly.

97% of participants ended up completing this follow-up questionnaire. 

Integration with other technologies

Prof. Gangestad and the team used Qualtrics for the analysis. All the ‘separate studies’ were integrated into Qualtrics as a single data file, making data management easy.

The results

Data analysis is still ongoing for this project, but so far, Prof. Gangestad and his team have found that:

• Women who are strongly bonded showed more sexual interest in their ovulatory phase.
• Women who were less bonded showed more sexual interest outside of their conceptive phase.

This suggests that non-conceptive and conceptive phases have different functions. Women may not be aware of the motives driving their sexual interest, but Prof. Gangestad and the team are starting to see what might be influencing it. 

The non-obvious, non-intuitive finding is that non-bonded women could be initiating more sex outside of the conceptive phase. However, it’s one piece of the puzzle they’re trying to fit together. 

Summary

Although the data is still being analyzed, what has been found so far indicates that women’s sexual interests are highly nuanced, especially when explored through a physiological framework relating to the menstrual cycle. 

With Prolific’s managed research service, Prof. Gangestad and the team could access high-quality, synced data based on strict criteria. By surveying women who demonstrated high participation rates, they were able to collect the specific data needed to come closer to understanding cisgender women’s sexual interests.

Click here to learn more about how Prolific’s managed research service can help your study.