Question

Dr. Stambaugh hypothesizes that a novel anxiety drug will affect memory. To examine this, the drug is administered to a random sample of 23 trained rats. The rats were then placed in a maze and timed on how long it took them to complete it. The average completion time was 47 seconds. Normal rats have an average completion time of 44 seconds with a standard deviation of 14 seconds. What can Dr. Stambaugh conclude with α = 0.01?

a) State the appropiate appropriate test statistic (na, z-test, one sample t test, independent- samples t test, related sample t test), population (normal rats, memory, trained rats, time to complete maze, the maze), and sample (normal rats, memory, trained rats, time to complete maze, the maze).
.


b) Compute the appropriate test statistic(s) to make a decision about H₀.
(Hint: Make sure to write down the null and alternative hypotheses to help solve the problem.)
critical value =  ; test statistic =  
Decision:  ---Select--- Reject H0 Fail to reject H0

c) If appropriate, compute the CI. If not appropriate, input "na" for both spaces below.
[  ,  ]

d) Compute the corresponding effect size(s) and indicate magnitude(s).
If not appropriate, input and select "na" below.
d =  ;   ---Select--- na, trivial effect ,small effect ,medium effect , or large effect
r² =  ;   ---Select--- na trivial effect small effect medium effect large effect

Now, Make an interpretation based on the results.

Rats on the anxiety drug were significantly slower completing the maze.

Rats on the anxiety drug were significantly quicker completing the maze.    T

he anxiety drug did not affect rats in completing the maze.

Answer 1

a)

z-test since population SD is known

population: normal rats

and sample trained rats

(b)

Here we have -47,o 14, n 23 Hypotheses are: Но : и3 44 н:и+ 44 Level of significance: a 0.01 Test is two tailed Test Statistics: (47-44)/(14/sqrt(23)) Z= _ = 1.03 Critical value: 2.576 If |z> 2.576, Reject HO Rejection Region: Decision: Since test statistics deos not lie in rejection region so we fail to reject the null hypothesis P-value 0.303 P-value: Decision: Since p-value is not less than level of significance so we fail to reject the null hypothesis Excel function for critical value: =NORMSINV(1-0.01) =2*(1-NORMSDIST(1.03)) Excel function for p-value:

(c)

Here we have -47,o 14, n =23 Level of significance: a/2 0.005 Critical value: Z 2.576 The requried confidence interval is: 47 (14*2.576/sqrt(23) 47 t 7.5199 (39.48,54.52) Excel function for critical value: =NORMSINV(1-0.005) Hence, the required confidence interval is (39.48,54.52)

(d)

47 44 = 0.21 14

The effect size is small.

r2 is not appropriate here.

The anxiety drug did not affect rats in completing the maze.