Appendix A. Table A.1. Values for <em>Factor</em>(.) in Equation (1) of Text, by the Number of Degrees of Freedom, for One- and Two-Tailed Tests, and at 80 and 85 Percent Power

Technical Methods Report: Statistical Power for Regression Discontinuity Designs in Education Evaluations

NCEE 2008-4026
August 2008

List of Tables

Appendix A.

Table A.1. Values for Factor(.) in Equation (1) of Text, by the Number of Degrees of Freedom, for One- and Two-Tailed Tests, and at 80 and 85 Percent Power

Number of Degrees of Freedom	One-Tailed Test		Two-Tailed Test
Number of Degrees of Freedom	80 Percent Power	85 Percent Power	80 Percent Power	85 Percent Power
2	3.98	4.31	5.36	5.69
3	3.33	3.61	4.16	4.43
4	3.07	3.32	3.72	3.97
5	2.94	3.17	3.49	3.73
6	2.85	3.08	3.35	3.58
7	2.79	3.02	3.26	3.49
8	2.75	2.97	3.20	3.42
9	2.72	2.93	3.15	3.36
10	2.69	2.91	3.11	3.32
11	2.67	2.88	3.08	3.29
12	2.66	2.87	3.05	3.26
13	2.64	2.85	3.03	3.24
14	2.63	2.84	3.01	3.22
15	2.62	2.83	3.00	3.21
20	2.59	2.79	2.95	3.15
30	2.55	2.75	2.90	3.10
40	2.54	2.74	2.87	3.07
50	2.53	2.72	2.86	3.06
60	2.52	2.72	2.85	3.05
70	2.51	2.71	2.84	3.04
80	2.51	2.71	2.84	3.04
90	2.51	2.71	2.83	3.03
100	2.51	2.70	2.83	3.03
Infinity	2.49	2.68	2.80	3.00
Note: All figures assume a 5 percent significance level.