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. Author manuscript; available in PMC: 2014 Jul 2.
Published in final edited form as: J Cyst Fibros. 2010 Jun 19;9(5):332–338. doi: 10.1016/j.jcf.2010.05.004

Table 2.

Sample sizes required to detect a 50% reduction in rate of decline as a function of study duration and measurement frequency

Subjects required per arm*
Study Duration,
yrs		 Quarterly
Measures		 Semiannual
Measures		 Annual
Measures
1.00 374 315 320
1.25 321 - -
1.50 274 223 -
1.75 301 - -
2.00 268 190 200
2.25 239 - -
2.50 223 171 -
2.75 221 - -
3.00 211 162 164
3.25 193 - -
3.50 182 148 -
3.75 180 - -
4.00 175 143 138
*

1:1 randomization, 80% power, α = 0.05