Skip to main content
. Author manuscript; available in PMC: 2015 Mar 1.
Published in final edited form as: Mov Disord. 2013 Oct 21;29(3):311–319. doi: 10.1002/mds.25657

TABLE 3.

Required sample size (boldface) for a hypothetical clinical trial of efficacya

Parameter Estimates Effect Size

Dropout, % Min CAP Type I error, % βS G11 G12 G22 σ2e 30% 40% 50% 60% 70%
0 290 5 1.56 21.40 4.45 3.20 16.54 552 310 199 138 101
0 350 5 2.04 25.96 5.61 3.67 19.39 377 212 136 94 69
0 400 5 2.81 32.11 6.56 5.26 24.63 263 148 95 66 48
0 290 10 1.56 21.40 4.45 3.20 16.54 402 226 145 101 74
0 350 10 2.04 25.96 5.61 3.67 19.39 275 155 99 69 51
0 400 10 2.81 32.11 6.56 5.26 24.63 192 108 69 48 35

10 290 5 1.56 21.40 4.45 3.20 16.54 591 332 213 148 109
10 350 5 2.04 25.96 5.61 3.67 19.39 404 227 145 101 74
10 400 5 2.81 32.11 6.56 5.26 24.63 281 158 101 70 52
10 290 10 1.56 21.40 4.45 3.20 16.54 431 242 155 108 79
10 350 10 2.04 25.96 5.61 3.67 19.39 295 166 106 74 54
10 400 10 2.81 32.11 6.56 5.26 24.63 205 115 74 51 38

20 290 5 1.56 21.40 4.45 3.20 16.54 636 358 229 159 117
20 350 5 2.04 25.96 5.61 3.67 19.39 435 245 157 109 80
20 400 5 2.81 32.11 6.56 5.26 24.63 303 170 109 76 56
20 290 10 1.56 21.40 4.45 3.20 16.54 464 261 167 116 85
20 350 10 2.04 25.96 5.61 3.67 19.39 317 178 114 79 58
20 400 10 2.81 32.11 6.56 5.26 24.63 221 124 79 55 41
a

The single-arm sample size is for a treatment–placebo slope difference analyzed with linear mixed effects regression. Sample size is listed as a function of percentage of dropout, minimum CAP, Type I error rate, estimated parameters, and effect size. Details are provided in the Appendix.

Abbreviations: Min, minimum; CAP, age-CAG product.