The original BDI, first published in 1961, consisted of twenty-one questions about how the subject has been feeling in the last week. Each question has a set of at least four possible answer choices, ranging in intensity. For example:
(0) I do not feel sad.
(1) I feel sad.
(2) I am sad all the time and I can't snap out of it.
(3) I am so sad or unhappy that I can't stand it.
When the test is scored, a value of 0 to 3 is assigned for each answer and then the total score is compared to a key to determine the depression's severity. The standard cut-offs are as follows:
0–9: indicates minimal depression
10–18: indicates mild depression
19–29: indicates moderate depression
30–63: indicates severe depression.
Higher total scores indicate more severe depressive symptoms.
Some items on the BDI have more than one statement marked with the same score. For instance, there are two responses under the Mood heading that score a 2: (2a) I am blue or sad all the time and I can't snap out of it and (2b) I am so sad or unhappy that it is very painful.
The BDI-IA was a revision of the original instrument, developed by Beck during the 1970s and copyrighted in 1978. To improve ease of use, the "a and b statements" described above were removed, and respondents were instructed to endorse how they had been feeling during the preceding two weeks. The internal consistency for the BDI-IA was good, with a Cronbach's alpha coefficient of around 0.85, meaning that the items on the inventory are highly correlated with each other.
However, this version retained some flaws; the BDI-IA only addressed six out of the nine DSM-III criteria for depression. This and other criticisms were addressed in the BDI-II.
The BDI-II was a 1996 revision of the BDI, developed in response to the American Psychiatric Association's publication of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, which changed many of the diagnostic criteria for Major Depressive Disorder.
Items involving changes in body image, hypochondria, and difficulty working were replaced. Also, sleep loss and appetite loss items were revised to assess both increases and decreases in sleep and appetite. All but three of the items were reworded; only the items dealing with feelings of being punished, thoughts about suicide, and interest in sex remained the same. Finally, participants were asked to rate how they have been feeling for the past two weeks, as opposed to the past week as in the original BDI.
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