Russel-Research-Method-in-Anthropology

620 Chapter 20
This confirms the weak, negative association we saw from the results of the
gamma test. Kendall’s T b will usually be smaller than gamma because gamma
ignores tied pairs, while T b uses almost all the data (it ignores the relatively
few pairs that are tied on both variables).
Yule’s Q: Gamma for 2 2 Tables
Yule’s Q is the equivalent of gamma for 2 2 tables of ordinal variables,
like high vs. low prestige, salary, education, religiosity, and so on. Yule’s Q
can be calculated on frequencies or on percentages. The formula is:
Q adbc
adbc
Formula 20.17
Yule’s Q is a handy, easy-to-use statistic. A good rule of thumb for interpreting
Q is given by Davis (1971): When Q is 0, the interpretation is naturally
that there is no association between the variables. When Q ranges between
from 0 to –.29, or from 0 to .29, you can interpret this as a negligible or
small association. Davis interprets a Q value of .30 to .49 as a ‘‘moderate’’
association; a value of .50 to .69 as a ‘‘substantial’’ association; and
a value of .70 or more as a ‘‘very strong’’ association.
Rutledge (1990) was interested in the effect of one- or two-parent families
on children’s relations with their mothers and fathers. She surveyed African
American, college-aged women, mostly from Chicago. One of the questions
she asked was: ‘‘When you were growing up, how close were you to your
father? Were you considerably close, moderately close, or not close at all?’’
I’ve collapsed Rutledge’s data into two response categories, close and not
close, in table 20.11.
TABLE 20.11
Family Structure and Self-Reported Closeness to Parents
Close to father? Two Parents One Parent Total
Yes 135 36 171
No 13 31 44
Total 148 67 215
SOURCE: E. M. Rutledge, ‘‘Black Parent-Child Relations: Some Correlates,’’ Journal of Comparative Family
Studies, Vol. 21, pp. 369–378, 1990. Reprinted by permission.
Here is the calculation of Yule’s Q for these data:
Q (135)(31)(36)(13)
(135)(31)(36)(13) 4,185468
4,185468 .80