Percentaging crosstabs[1]
The
rule for percentaging crosstabs is that you percentage within each category of
the independent variable. You then interpret the table by comparing percentage
point differences for different categories of the independent variable.
So, in
our wealth and art galleries example, the wealth of the tract is considered to
be the independent variable and the number of art galleries in a tract is the
dependent variable. (The implicit causal logic is that richer tracts can
support more art establishments than poorer tracts.)
Since
the independent variable is arrayed in the columns, we compute percentages
within each column separately. The frequencies within each cell are divided by
the total of the column in which they are located, and the column totals should
sum to 100%. When the independent variable is arrayed in rows, we compute
percentages within each row separately.
|
|
|
Average wealth of tract |
|
|
|
|
|
Rich |
Poor |
Total |
|
Art Galleries |
Many |
75% (30) |
16.5% (10) |
40% (40) |
|
Few |
25% (10) |
83.5% (50) |
60% (60) |
|
|
|
Total |
100% (40) |
100% (60) |
100% (100) |
[1] This discussion is taken
from Text: Chava Frankfort-Nachmias and Anna Leon-Guerrero. 2000. Social Statistics for a Diverse Society, 2nd
ed. Thousand Oaks, CA: Sage Publications, p. 207.