Study Design & Power Analysis · TOOL GUIDE

Effect Size Calculator

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Understand the method. Use it with confidence.

Calculate Cohen's d or Eta Squared from summary stats. Quantly runs the method against your active analysis context and returns structured results for review and interpretation.

01

When to use it

Use this tool before collecting data to plan sample size, precision, allocation, or detectable effects.
Use it only when the selected variables and study design match the method's requirements.

02

How to use it

  1. Open the tool from the Quantly Tools panel.
  2. Confirm the active dataset and analysis session.
  3. Set Calculation Type (Required): Choose the type of effect size to calculate.
  4. Set Mean 1 (Group 1) (Optional): Required for Cohen's d
  5. Set Standard Deviation 1 (Optional): Required for Cohen's d
  6. Set Sample Size 1 (Optional): Required for Cohen's d (for pooled SD)
  7. Set Mean 2 (Group 2) (Optional): Required for Cohen's d
  8. Set Standard Deviation 2 (Optional): Required for Cohen's d
  9. Set Sample Size 2 (Optional): Required for Cohen's d (for pooled SD)
  10. Set F-Statistic (Optional): Required for Eta Squared
  11. Set Degrees of Freedom 1 (Between) (Optional): Required for Eta Squared
  12. Set Degrees of Freedom 2 (Error) (Optional): Required for Eta Squared
  13. Review optional or advanced settings and keep defaults unless your design requires a change.
  14. Run the tool, inspect warnings and diagnostics, then save or export the result with its assumptions.
03

How to interpret results

Treat the result as a planning estimate driven by the assumptions you entered. Recalculate under plausible alternative effect sizes, variability, attrition, and significance levels.