PSYCH/655 v5
Psychometrics
Reliability and Validity Worksheet
Instrument Reliability
Imagine that you must develop a test to measure state anxiety. You develop a 30-question test. The
scores of the normative sample on the two administrations of the test are listed below. Use Microsoft®
Excel® to create a scatterplot with the provided scores, formatted as shown in the example graph.
30-Point Test to Measure State Anxiety
Examine
e
First
Administratio
n
Second
Administratio
n
A
17
15
B
22
18
C
25
21
D
12
15
E
7
14
F
28
27
G
27
24
H
8
5
I
21
25
J
24
21
K
27
27
L
21
19
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Reliability and Validity Worksheet
PSYCH/655 v5
Page 2 of 2
Answer the following questions about the scatterplot and data:
1. What type of reliability assessment does this represent?
2. What conclusions can you draw about the reliability of the test based upon the scatterplot? Why do
you draw these conclusions?
3. Would you say this method of reliability assessment is the best to use to evaluate the reliability of test
to design the construct of state anxiety? Why or why not?
Instrument Validity
A valid instrument is one that measures what it says it measures. Validity depends on the amount and
type of evidence there is to support one’s interpretations concerning data that has been collected. This
week, you discussed three kinds of evidence that can be collected regarding validity: content-related,
criterion-related, and construct-related evidence.
1. How would you evaluate the validity of the test described above? Provide a plan to evaluate each
type of validity listed below:
• Content-related
• Criterion-related
• Construct-related
2. Assume the test above correlates with the State-Trait Anxiety Inventory with a correlation coefficient
of .20. What type of validity would this correlation represent? What does this correlation show about
the validity of the new instrument?
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