Question 1168566: It's well established that lab rats require, on average, 32 trials before reaching a criterion of 3 consecutive errorless trials in a complex water maze. To determine whether a mildly painful stimulus has any effect on performance, a sample of twelve rats were given a mild electrical shock just before each trial. They required the following number of trials before reaching the criterion: 35, 37, 38, 34, 32, 31, 35, 29, 30, 35, 35, 39. Does the mild shock affect the rats performance?
Questions are: 1. Statistical Hypotheses?
2. Reject the null hypothesis at the .05 level of significance if t ≥ __ or or t ≤ __ given __ df.
3. Given that the mean of the sample is 34.17 with a sample standard deviation of 3.13, calculate the one sample t test by hand.
4. What is your decision?
5. How do you interpret your decision?
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! Ho: mean before=mean after
Ha: means are not equal (two-tail)
t(0.975,df=11)=2.201
t=(x bar-mean)/s/sqrt(n)
=2.17/3.13/sqrt(32)
=2.17*sqrt(32)/3.13
=3.92
Reject Ho. The means are not the same.
2. reject if t> 2.201 or t<=2.201 given 11 df.
3. see above.
4. same
5. Mild shock affects the rats' performance.
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