A cognitive psychologist measures the reaction times of 6 subjects to emotionally laden words. The following scores in seconds are recorded: 25, 27, 31, 36, 42, 47. The psychologist wants to know how her subject compared to a national sample who scored

a. Mean

b. Median

c. Mode

d. Range

e. Variance

f. Standard Deviation

g. If Sally’s reaction time is 25 second, what’s my z-score for this sample? How many standard deviations is sally away from the mean?

Now the psychologist from Problem 1 wants to know how her sample compares to a national sample of people who scored an average of 35 seconds with a standard deviation of 3.00.

a. State her null and alternative hypotheses.

b. What statistical test would you use? Why?

c. Is this a two-tail or one-tail test?

d. What alpha level are you using and what is its corresponding critical value?

e. Use the appropriate test to calculate the needed value for your test.

f. Summarize your result.

A physiologist has the hypothesis that hormone Z is important in increasing sexual behavior. To investigate this hypothesis, 4 rats were randomly selected to take hormone Z. The rats were injected with hormone Z and then were placed in individual housing with a sexually receptive female rat. The physiologist took note of the number of times these rats mated before and after they had the injection. The results are shown in the table below:

Pre-injection Post-injection

4 6

4 7

5 8

6 6

X ?_pre= 4.75 X ?_post= 6.75

What are the IV and DV?

What are the null and alternative hypotheses?

Is this a two-tail or one-tail test?

Which statistical test would you use? Why?

What alpha level are you using and what is its corresponding critical value?

Use the appropriate test to calculate the needed value for your test.

Summarize your results.