PSYC 331 –
Statistics for Psychologists

Assignment
I

To be
submitted by 5pm on Wednesday, 20 November 2019.

Answer all
questions

Assignment
must be typed and printed. Indicate your student ID number on front page. Use
font size 12 and 1.5 lines spacing (Times New roman font).

1. Your
company wants to improve sales. Past sales data indicate that the average sale
was ¢100 per transaction. After training your sales team, recent sales data (taken
from a sample of 25 salespersons) indicates an average sale of ¢130, with a
standard deviation of ¢15. Did the training work? (Do not show full working steps)

2. A study was conducted to
test the effect of self-imagery on social anxiety. Participants in the study rehearsed
a negative self-image or a positive self-image prior to giving a speech. The
researchers found that the negative image group felt more anxious than the
positive image group. Assuming social anxiety was measured on an interval scale
and that the scores were normally distributed, what statistical test would be
most appropriate for testing the research hypothesis? Explain your answer.

3. A psychologist
theorized that people could hear better when they have just eaten a large meal.
Six individuals were randomly assigned to eat either a large meal or a small
meal. After eating the meal, their hearing was tested. Assuming hearing ability
was measured on an interval scale and that the scores were normally
distributed, what test would be most appropriate for testing the research hypothesis?
Explain your answer.

4. A study of the effects
of color on reducing anxiety compared anxiety test scores of participants who
completed the test printed on either soft yellow paper or on harsh green paper.
The scores for five participants who completed the test printed on the yellow
paper were 17, 19, 28, 21, and 18. The scores for four participants who
completed the test on the green paper were 20, 26, 17, and 24. Using the .05
level, one-tailed (predicting lower anxiety scores for the yellow paper), what
should the researcher conclude? (Do not show full working steps)

5. A group of
researchers surveyed 58 people when they first started using Facebook (the
researchers called this “Time 1”) and again 3 months later (referred to as
“Time 2” by the researchers). At both time points, the participants completed a
measure of social integration (a sense of belonging to a group of friends).
Assuming
the measure of social integration was on an interval scale, what statistical test
would the researchers use in testing their research hypothesis? Explain your
answer.

6. A program to decrease
littering was carried out in the University of Ghana starting in August 2018.
The amount of litter in the streets (average kilograms of litter collected per
block per day) was measured during July before the program started and then the
next July, after the program had been in effect for a year. What statistical
test would be most appropriate for testing whether the amount of littering
reduced? Explain your answer.

7. To determine whether caffeine
consumption affects the ability to solve math problems, a researcher had one
group solve math problems after taking a cup of caffeinated drink and another
group solve math problems after taking a cup of water. The group who took the
caffeinated drink completed 35 problems in one hour and the group that had
water completed 20 problems in one hour. Assuming the number of problems solved
is normally distributed in each group, what statistical test would be used to
test the research hypothesis? Explain your answer.

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