Suppose you are planning an experiment to test the effects o

Suppose you are planning an experiment to test the effects of various diets on the weight gain of young turkeys. The observed variable will be Y = weight gain in three weeks (measured over a period starting one week after hatching and ending three weeks later). Previous experiments suggest that the standard deviation of Y under a standard diet is approximately 80 g.23 Using this as a guess of s, determine how many turkeys you should have in a treatment group, if you want the standard error of the group mean to be no more than

(a) 20g

(b)15g

Solution

As

SE = s/sqrt(n)

Then

n = (s/SE)^2

Thus,

a)

n = (80/20)^2 = 16 [ANSWER]

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b)

n = (80/15)^2 = 28.44444444

rounding up,

n = 29 [ANSWER]