A research psychologist wants to determine if alcohol consumption affects the am

Question

A research psychologist wants to determine if alcohol consumption affects the amount of dreamtime, as measured by rapid eye movements, among young adult volunteers. The dreamtimes are monitored for each of 20 volunteers during two sleep periods: one sleep period following a controlled evening of excessive alcohol consumption.  

1.____ To analyze the test results, the research psychologist should use a t test for two matched samples because

subjects are all young adults                      

equal numbers of subjects participate in both periods

the same subjects is measured twice        

each subject is monitored for rapid eye movement

2.____ The number of degrees of freedom equals

               a.   18                       b.    19             c.    20             d.   38

____ Given only the information above, it would be appropriate to test the null hypothesis with a

two-tailed test at the .05 level of significance                     

one-tailed test, lower tail critical, at the .05 level of significance

one-tailed test, upper tail critical, at the .05 level of significance

either a one- or two tailed test, but at the .001 level of significance

3.____ It would be most important that subjects experience the two conditions in

the same order and on consecutive nights (before any alcohol effect disappears)

the same order and on nonconsecutive nights (after any alcohol effect disappears)

counterbalanced order and on consecutive nights (before any alcohol effect disappears)

counterbalanced order and on nonconsecutive nights (after any alcohol effect disappears)

4.____ The basic unit of analysis is each subject’s

score for each sleep period            

total score

mean score             

different score

Explanation / Answer

1)

To analyze the test results, the research psychologist should use a t test for two matched samples because the same subjects is measured twice. (which is the case of using paired t-test)

2)

The number of degrees of freedom equals to n-1=20-1= 19

Given only the information above, it would be appropriate to test the null hypothesis with a one-tailed test, upper tail critical, at the .05 level of significance because we want to see whether alcohol consumption increases the dream time.

3)

It would be most important that subjects experience the two conditions in the same order and on nonconsecutive nights (after any alcohol effect disappears)

4)

The basic unit of analysis is each subject’s mean score. Mean scores will determine whether alcohol consumption increases dream time.

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