Statistics for laboratory scientists

Solutions for the homework problems for lecture 17

1. 1. In R, do the following:

      C <- qt(0.975, 23) # critical value
se <- 15*sqrt(1/15 + 1/10) # true standard error of the mean difference
1 - pt(C, df=23, ncp=10/se) + pt(-C, df=23, ncp=10/se)

      The answer: Power = 34.7%

   2. C <- qt(0.975, 23) # critical value
se <- 15*sqrt(1/15 + 1/10) # true standard error of the mean difference
1 - pt(C, df=23, ncp=20/se) + pt(-C, df=23, ncp=20/se)

      The answer: Power = 87.8%

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Last modified: Thu Mar 2 12:53:47 EST 2006