Descriptive Statistics by Groups (Breakdown) Introductory Overview - Arrangement of Data

In the following example data set (spreadsheet), the dependent variable WCC (White Cell Count) can be broken down by 2 independent variables: Gender (values: males and females), and Height (values: tall and short):

 

GENDER

HEIGHT

WCC

case 1

male

short

101

case 2

male

tall

110

case 3

male

tall

92

case 4

female

tall

112

case 5

female

short

95

...

...

...

...

The resulting breakdowns might look as follows (we are assuming Gender was specified as the first independent variable, and Height as the second):

Entire sample

Mean=100

SD=13

N=120

Males

Mean=99

SD=13

N=60

Females

Mean=101

SD=13

N=60

Tall/males

Mean=98

SD=13

N=30

Short/males

Mean=100

SD=13

N=30

Tall/females

Mean=101

SD=13

N=30

Short/females

Mean=101

SD=13

N=30

The composition of the "intermediate" level cells of the "breakdown tree" depends on the order in which independent variables are arranged. For example, in the above example, you see the means for "all males" and "all females" but you do not see the means for "all tall subjects" and "all short subjects," which would have been produced had you specified independent variable Height as the first grouping variable rather than the second. Thus, ideally, in a breakdown program you should have an option to easily "reorder" independent variables and thus see different "cross-sections" of the data. The Basic Statistics and Tables module gives you not only the option to reorder the variables in the table, but it also allows you to compute any marginal table in which you may be interested. For example, you could easily compute the means for Tall and Short individuals.