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Exercise 2: Instrument Evaluation – Beck Depression Inventory-II
1. Describe and evaluate the norm group. Do you think it is representative? Do you think the norm group is
current? Do you believe the size of the norm group was large enough? Are the samples related to the population
you intend to use the test with? Explain.
The BDI norm group appears representative for individuals with depressive symptoms since it is make up
individuals from rural and suburban areas who sought outpatient therapy. However, no attempt was made
to account for such variables as ethnicity; for example, 91% of the sample consisted of individuals
identified as “White,” which clearly does not represent a diverse population.
The BDI-II was published in 1996, which indicates that the norm group may be somewhat out of date.
Because the BDI-II has a narrow focus and was developed to measure the severity of depression in
individuals, the relatively small sample size of 500 is appropriate.
As a mental health counselor who is working in an outpatient clinic with adult clients, and who is looking
for an instrument that specifically assess depressive symptoms among my clients, the BDI-II
standardization sample is related to the population I intend to use it with. Because it was developed for
persons 13 years of age and older, it is also representative of the age group of my clients.
2. Describe and evaluate each method used to estimate reliability. Does the reliability evidence support a decision
to use the instrument? Explain.
Analysis of internal consistency reliability for the BDI-II yielded a Cronbach alpha of .92 and .93. These
are very high reliability coefficients, which indicate that the items within the inventory are homogeneous.
For the test-retest method of estimating reliability, the correlation coefficient over a one week interval was
.93 (for a subsample of 26). This coefficient is very high and indicates that scores are consistent from one
test administration to the next (with a one week interval).
3. Describe and evaluate each type of validity evidence. Does the validity evidence support a decision to use the
Content validity evidence for the BDI-II appears to be strong since the items were designed to be consistent
with the diagnostic criteria for depression in the DSM-IV-TR.
Convergent validity evidence includes correlations between the BDI-II and other scales measuring
depressive symptoms with coefficients of .68, .71, and .89. These coefficients are all very high indicating a
strong relationship between BDI-II scores and scores on other similar instruments.
For discriminant validity, correlation coefficients between the BDI-II and two measures of anxiety were
provided. These correlations (.47 and .60) indicated a strong relationship between the scores on the BDI-II
and the scores on the anxiety measures. This is not strong evidence of discriminant validity.
4. Describe the practical aspects of the instrument, focusing on issues related to time required for administration,
ease of administration and ease of scoring.
The BDI-II has 21 items, is a self-report inventory, takes 5-10 minute to complete, and scores are
easily calculated by summing the item totals.
5. Summarize the strengths and weakness of the inventory.
Norm group consists of individuals seeking therapy in outpatient clinics and appears large enough.
Strong internal consistency reliability and test-retest reliability
Strong evidence of content validity and convergent validity
The instrument appears very practical to use
Norm group does not appear to represent individuals from diverse racial/ethnic backgrounds
Poor discriminant validity evidence
6. Based on your review of the BDI-II, would you adopt this instrument? Explain your answer.
Based on the strong evidence of validity and reliability alone, I would adopt this instrument. However, I
would be cautious about its results based on the lack of a diverse norm group, particularly when
administering it to non-White individuals.