Russel-Research-Method-in-Anthropology

The Foundations of Social Research 49
A Rule about Measurement
Remember this rule: Always measure things at the highest level of measurement
possible. Don’t measure things at the ordinal level if you can measure
them as ratio variables.
If you really want to know the price that people paid for their homes, then
ask the price. Don’t ask them whether they paid ‘‘less than a million pesos,
between a million and five million, or more than five million.’’ If you really
want to know how much education people have had, ask them how many years
they went to school. Don’t ask: ‘‘Have you completed grade school, high
school, some college, four years of college?’’
This kind of packaging just throws away information by turning intervallevel
variables into ordinal ones. As we’ll see in chapter 10, survey questions
are pretested before going into a questionnaire. If people won’t give you
straight answers to straight questions, you can back off and try an ordinal
scale. But why start out crippling a perfectly good interval-scale question by
making it ordinal when you don’t know that you have to?
During data analysis you can lump interval-level data together into ordinal
or nominal categories. If you know the ages of your respondents on a survey,
you can divide them into ‘‘old’’ and ‘‘young’’; if you know the number of
calories consumed per week for each family in a study, you can divide the
data into low, medium, and high. But you cannot do this trick the other way
around. If you collect data on income by asking people whether they earn ‘‘up
to a million pesos per year’’ or ‘‘more than a million per year,’’ you cannot go
back and assign actual numbers of pesos to each informant.
Notice that ‘‘up to a million’’ and ‘‘more than a million’’ is an ordinal variable
that looks like a nominal variable because there are only two attributes. If
the attributes are rankable, then the variable is ordinal. ‘‘A lot of fish’’ is more
than ‘‘a small amount of fish,’’ and ‘‘highly educated’’ is greater than ‘‘poorly
educated.’’ Ordinal variables can have any number of ranks. For purposes of
statistical analysis, though, ordinal scales with five or more ranks are often
treated as if they were interval-level variables. More about this in chapter 20
when we get to data analysis.
Units of Analysis
One of the very first things to do in any research project is decide on the
unit of analysis. In a case study, there is exactly one unit of analysis—the
village, the school, the hospital, the organization. Research designed to test