Russel-Research-Method-in-Anthropology

Univariate Analysis 563
people hanging around who aren’t old enough to leave and old people who
can’t find work in the city because of their age.
Using the Mode
The mode is often said to be the weakest measure of central tendency, but
it’s very useful when you want to make a statement about a prominent qualitative
attribute of a group. ‘‘More people profess to be Buddhist in this prefecture
of Japan than profess any other religion’’ is such a statement.
The mode is also a good common-sense alternative to the sometimes unrealistic
quality of the mean. Saying that ‘‘the modal family size is 4 people’’
makes a lot more sense than saying that ‘‘the average family size is 3.81 people’’—even
if both statements are true.
You’ll often see the mode reported as a percentage: ‘‘In this survey, 60% of
the respondents were men.’’
The mode can also be reported in terms of ratios. Of the 30 respondents in
table 19.2, 12 were women and 18 were men, so the modal value for the variable
GENDER in table 19.2 is male. The ratio of men to women among these
respondents is 18/12 1.5, while the ratio of women to men is 12/18 .67.
Reporting that ‘‘there were 1.5 men for every woman in this survey’’ is the
same as saying that ‘‘60% of the respondents were men.’’ Reporting that
‘‘there were .67 women for every man in this survey’’ is the same as saying
that ‘‘40% of the respondents were women.’’
Central Tendency: The Median
The median is the point in a distribution above and below which there are
an equal number of scores in a distribution. If you’ve ever taken a standardized
test like the ACT, SAT, or GRE, you might have been told that you scored
in the 14th percentile, or the 31st percentile, or whatever. If you scored in the
86th percentile, then 14% of the scores were higher than yours (.86 .14
1.0).
Ten percent of scores in a list are below the 10th percentile, and 90% are
above it. The 25th percentile is called the first quartile and the 75th percentile
is the third quartile. The difference between the values for the 25th and 75th
percentiles is known as the interquartile range and is a measure of dispersion
for ordinal and interval-level variables. (More on measures of dispersion
later.)
The median is the 50th percentile. It can be used with ranked or ordinal
data and with interval- or ratio-level data. For an odd number of unique obser-