Psych 101, Spring 2008, Midterm 1
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**ANSWER KEY**
1. (10 points) Estimate the correlation between the variables represented by each of the
following 10 scatterplots. (Write your estimate below each scatterplot.)
The correlations are (approximately):
1.0, 0.4, 0, 0, -0.8
0.8, 1.0, 0, 0, -1.0
One point for each correct answer
2. (5 points) Define the measurement scales associated with the following:
A seven-point rating scale:
Ordinal
The level of estrogen circulating in the bloodstream:
Ratio
Religious affiliation:
Nominal
The Stanford-Binet IQ test:
Interval
Your grade on this exam:
Ratio (raw scores) or
Interval (for z scores) or
Ordinal (letter grade)
One point for each correct answer
For the grade question, the default is Ratio unless you state which type of score you are
considering
3. As part of a class project Lilly decided to try to determine whether people who studied
harder were prone to caffeine addiction. She decided to ask people how much coffee they
drank and how many hours they had studied the day before the midterm.
Coffee:
0, 1, 2, 3, 4, 7, 8
Hours:
8, 1, 4, 2, 5, 8, 6
3a. (4 points) Plot these data in a form that best reveals the relationship between the
variables.
[Scatterplot of the data]
2 points for the correlation
2 points for labeling your axes correctly