Question

You are asked to develop a new drug that enhances memory in patients afflicted with Alzheimer’s disease. In general, placebos given to such patients tend to produce a mean memory score of μ = 4.6. You hypothesize that this drug produces better memory scores and carry out the experiment on a random sample of Alzheimer’s patients. Test with α = 0.01.

a. Perform the correct hypothesis test. Do show the 5 steps! The conclusion should be written using proper English grammar.
b. Determine the magnitude of the effect using a strategy that is comparable to computing a z-score. Do indicate its size.
c. Explain why the effect size in Part b is not consistent with the t value that was computed.

X

5

6

4

4

5

5

6

5

4

6

Answer 1

(a) The hypothesis being tested is:

H₀: µ = 4.6

H_a: µ > 4.6

4.600	hypothesized value
5.000	mean Data
0.816	std. dev.
0.258	std. error
10	n
9	df
1.549	t
.0779	p-value (one-tailed, upper)

The p-value is 0.0779.

Since the p-value (0.0779) is greater than the significance level (0.01), we fail to reject the null hypothesis.

Therefore, we cannot conclude that this drug produces better memory scores.

(b) Effect size = (5 - 4.6)/0.816 = 0.49

This is medium effect.

(c) This value is not consistent with the t-value becuase the sample size is independent of the sample size.