1. What Is Cohen's d?

Cohen's d is a measure of effect size used to indicate the standardized difference between two means. It is commonly used in statistical analysis to quantify the magnitude of a phenomenon.

2. How Does The Calculator Work?

The calculator uses Cohen's d formula:

Where:

• \( M_1 \) — Mean of group 1
• \( M_2 \) — Mean of group 2
• \( SD \) — Standard deviation (pooled or common)

Explanation: The formula calculates the difference between two means divided by the standard deviation, providing a standardized measure of effect size.

3. Importance Of Effect Size Calculation

Details: Effect size calculation is crucial for understanding the practical significance of research findings, complementing statistical significance tests, and facilitating meta-analyses.

4. Using The Calculator

Tips: Enter the means for both groups and the standard deviation. All values must be valid (SD > 0).

5. Frequently Asked Questions (FAQ)

Q1: What constitutes a small, medium, or large effect size?
A: Generally, d = 0.2 is considered small, d = 0.5 medium, and d = 0.8 large, though interpretation depends on context.

Q2: Can Cohen's d be negative?
A: Yes, a negative value indicates that the second mean is larger than the first mean.

Q3: When should pooled standard deviation be used?
A: When comparing two independent groups, pooled SD is typically used. For dependent samples, other formulas may be more appropriate.

Q4: Are there limitations to Cohen's d?
A: Cohen's d can be influenced by sample size and may overestimate effect size in small samples. It also assumes normality of data.

Q5: How is Cohen's d different from other effect size measures?
A: Unlike correlation-based measures, Cohen's d expresses effect size in standard deviation units, making it intuitive for mean differences.