Material; https://www.nature.com/articles/s41598-021-00143-7

Questions:

1. How was the study conducted (e.g. sample, correlation or experimental)?
2. What were their sample sizes and/or inclusion/exclusion criteria for sampling?
3. How were variables measured (in other words, what instrument did they use: things like heartrate, hormonal levels, self-report, scores on a scale, etc)?
4. What did they find?