A. Web-based Effect Size Calculator
B. Examples
- T: Treatment Group
- C: Control Group
- T(n): n for Treatment Group
- C(n): n for Control Group
- p: p-value
- std: standard deviation
| Data | ES |
| 1. Mean SES / Group/ n / std 127.8 / T / 25 / 10.4 132.3 / C / 30 / 132.3 | Standardized Mean Difference (d) Means and Standard Deviation d= -0.4466 |
| 2. t/ T(n) / C(n) 1.68 / 10 / 12 | Standardized Mean Difference (d) T-Test, Unequal Sample Size d= 0.7193 |
| 3. T(n) / C(n) / p 10 / 12 / .037 | Standardized Mean Difference (d) T-Test P-Value, Unequal Sample Size d= 0.9569 |
| 4. r = .27 for binary variable and continuous variable | 2*0.27/ sqrt(1-0.27^2) ES=0.560829 formula from D.W. Wilson’s slides |
| 5. Group / Mean test scroe / n 1 / 55.38 / 13 2 / 59.40 / 18 3 / 75.14 / 37 4 / 88 / 22 F(3,86) = 7.05, for meta-analysis only interested group 1 and 2, std not reported. | Standardized Mean Difference (d) F-Test, 3 or more Groups d= -0.1658 |
| 6. 2 x 2 table n / group / % not improved / % improved 42 / T / 32% / 68% 29 / C / 37% / 63% | Standardized Mean Difference (d) Frequency Distribution (Proportions) d= 0.1057 |
| 7. frequency table for T and C group, 60 cases for each group (no report of the means and stds) Degrees of Condition / T(n) / C(n) 0 / 15 / 20 1 / 15 / 20 2 / 15 / 10 3 / 15 / 10 | Standardized Mean Difference (d) Frequency Distribution d = 0.305 |
| 8. regression analysis with nonequivalent comparison group design covariates: employment status, marital status, age etc. treatment: intervention / probation only unstandardized regression coefficient: -.523 std for DV, severity of physical abuse: s=9.23 sample size (intervention / probation only) : n1= 125 / n2=254 | Standardized Mean Difference (d) Unstandardized Regression coefficient Covariates adjusted ES(d)= -0.0568 =(125-1)*9.23^2+ (254-1)*9.23^2 =32117.72 = 124+254-2 = 377 =32117.72 / 377 = 85.1929 =sqrt(85.1929)= 9.23 = S_pooled ES=-.523 /9.23 = -.056 |
C. Web-based Calculator Output
D. Citation
Wilson, D. B. (date of version). Meta-analysis macros for SAS, SPSS, and Stata. Retrieved November 3, 2019, from http://mason.gmu.edu/~dwilsonb/ma.html