Module 4 Assignment (A-4) | Complete Solution

Module 4 Assignment (A-4)
For this assignment you will use multiple data sets, each embedded within the assignment below.
Q1) Find the t values that form the boundaries of the critical region for a two-tailed test with α = .05 for
each of the following sample size (n) values.
a) n = 9
b) n = 16
c) n = 25
d) Using information from Q1 a – c above, what can you glean about the relationship between sample
size and critical region? And, how does this relationship impact the likelihood of finding significant
results?
Q2 and Q3:
Infants, even newborns, prefer to look at attractive faces compared to less attractive faces (Slater, et al.,
1998). In the study, infants from 1 to 6 days old were shown to photographs of women’s faces.
Previously a group of adults had rated one of the faces as significantly more attractive than the other.
The babies were positioned in front of a screen on which the photographs were presented. The pair of
faces remained on the screen until the baby accumulated a total of 20 seconds of looking at one or the
other. The number of seconds looking at the attractive face was recorded for each infant.
Number of
Seconds Spent
Looking at
Attractive Face
8
10
12
12
13
13
15
17
17
Q2) Use the dataset above to calculate each of the following statistics for “number of seconds spent
looking at attractive face”:
a) Mean of the sample
b) Estimated standard deviation of the population
c) Standard error of the sampling distribution
Q3) Use the statistics calculated in Q2 to determine whether babies look significantly longer at attractive
faces. If the babies had no preference (as stated by the null hypothesis) they would look at each face for
10 seconds. The psychologist must therefore rely on this population mean (Population Mean = 10) and
estimates of the population standard deviation and sampling distribution to conduct a hypothesis test.
Perform a hypothesis test with an alpha level of .05 and a two-tailed design (show all 5 steps of
hypothesis testing).
Q4 and Q5:
A researcher studies the effect of a Monoamine-oxidase inhibitor (MAOI) drug on the number of
nightmares occurring in veterans with Post-traumatic Stress Disorder (PTSD). The researcher asks a
sample of PTSD clients to record each incident of a nightmare for 1 month before treatment.
Participants are then given the medication for 1 month, and they continue to report each occurrence of
a nightmare. Use the following hypothetical data for Q4 and Q5.
Number of Nightmares
1 Month
Before
Treatment
1 Month
During
Treatment
6 1
10 2
3 0
5 5
7 2
Q4) Use the dataset above to calculate each of the following statistics for “Number of Nightmares”:
a) Difference score for each case within the data set. (A “case” is a corresponding pair of scores)
b) Mean difference score
c) Standard error of the sampling distribution
Q5) Use the statistics calculated in Q3 to conduct a hypothesis test to determine whether the MAOI
significantly reduces nightmares in the veteran sample. Perform a hypothesis test with an alpha level of
.05 and a two-tailed design (show all 5 steps of hypothesis testing).
Extra Credit (3 points):
Assume you are talking to a layperson about statistics. In no less than 5 sentences, and in your own
words, explain what is meant by the statistical power of an experiment.