Table 2.

Correspondence among measures of effect.

Common interpretation	Standardized mean difference	Correlation coefficient	Odds ratio	Relative Risk		Risk Difference
				P0 = 0.01	P0 = 0.20	P0 = 0.01	P0 = 0.20
Very small	0.01	0.00	1.02	1.02	1.01	0.000	0.003
–	0.02	0.01	1.04	1.04	1.03	0.000	0.006
–	0.05	0.02	1.09	1.09	1.07	0.001	0.015
–	0.10	0.05	1.20	1.20	1.15	0.002	0.031
–	0.15	0.07	1.31	1.31	1.24	0.003	0.047
Small	0.2	0.10	1.44	1.43	1.32	0.004	0.064
–	0.3	0.15	1.72	1.71	1.51	0.007	0.101
–	0.4	0.20	2.07	2.04	1.70	0.010	0.141
Medium	0.5	0.24	2.48	2.44	1.91	0.014	0.182
–	0.6	0.29	2.97	2.91	2.13	0.019	0.226
–	0.7	0.33	3.56	3.47	2.35	0.025	0.271
Large	0.8	0.37	4.27	4.13	2.58	0.031	0.316
–	0.9	0.41	5.12	4.91	2.81	0.039	0.361
–	1	0.45	6.13	5.83	3.03	0.048	0.405
–	1.1	0.48	7.35	6.91	3.24	0.059	0.448
Very large	1.2	0.51	8.82	8.18	3.44	0.072	0.488
–	1.3	0.54	10.57	9.65	3.63	0.086	0.525
–	1.4	0.57	12.67	11.35	3.80	0.103	0.560
–	1.5	0.60	15.19	13.30	3.96	0.123	0.592
–	1.75	0.66	23.91	19.45	4.28	0.185	0.657
Huge	2	0.71	37.62	27.54	4.52	0.265	0.704
–	2.25	0.75	59.21	37.42	4.68	0.364	0.737
–	2.5	0.78	93.18	48.48	4.79	0.475	0.759

See Box 1 for formulas and assumptions used to convert among measures of effect. P₀: Risk of outcome among unexposed or untreated.