Russel-Research-Method-in-Anthropology

Bivariate Analysis: Testing Relations 613
TABLE 20.8
Dobkin de Rios’s Data on Experience with Witchcraft by Gender
Women clients Men clients Row totals
Personal experience with witchcraft 63 12 75
No personal experience with witchcraft 5 15 20
Column totals 68 27 95
2 using formula 20.9
2
95(945 60)2
(75)(20)(68)(27) 74,406,375 27.02 p.001
2,754,000
SOURCE: Reprinted from Social Science and Medicine, Vol. 15B, M. Dobkin de Rios ‘‘Socioeconomic Characteristics
of an Amazon Urban Healer’s Clientele,’’ pp. 51–63, 1981, with permission of Elsevier.
The Odds Ratio
The odds ratio, while also not a PRE statistic, is a measure of the relation
between nominal variables. In table 20.8, among those who report having personal
experience with witchcraft the odds are 5.25-to-1 that it’s a woman (63/
12 5.25). Among those who report not having had personal experience with
witchcraft, the odds are one-third (5/15 .33) that it’s a man.
For 2 2 tables, the two primary odds are a/c and b/d. The odds ratio is
a/c
b/d
Formula 20.10
which can be collapsed to simply ad/bc. The odds ratio for is table 20.8 is:
945/60 15.75
If the ratio of a/c were the same as the ratio of b/d, then the odds ratio would
be 1. The degree to which the odds ratio is not 1 is a measure of association
between the variables. In this case, the ratio of a/c is more than 15 times bigger
than the ratio of b/d. This means that women clients are that much more likely
than men clients to have had personal experience with witchcraft.
Fisher’s Exact Test
Notice that there are only five cases in one of the cells in table 20.8—
women who report no personal experience with witchcraft. When there are