26: Interpreting effect sizes

When interpreting the magnitude of group differences using effect sizes, researchers often rely on Cohen's guidelines for small, medium, and large effects. However, Cohen originally proposed these guidelines as a fall back when the distribution of effect sizes was unknown. Despite the hundreds of available studies comparing heart rate variability (HRV), Cohen's guidelines are still used for interpretation. In this episode, Dan discusses his recent preprint describing an effect size distribution analysis on HRV studies.

Some of the topics discussed:

• A summary of Dan's preprint
• What is an effect size?
• What can an effect size distribution tell us?
• How effect sizes can inform study planning
• How close are Cohen's guidelines to the distribution of HRV effect sizes?
• What samples sizes are appropriate?
• Pre-publication review vs. post-publication review
• Statcheck

Links

• The preprint article

http://www.biorxiv.org/content/early/2016/08/31/072660

• Statcheck

https://mbnuijten.com/statcheck/

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