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Home arrow Environment arrow Research Methods in Anthropology: Qualitative and Quantitative Approaches
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ACCURACY

Even when people tell you what they think is the absolute truth, there is still the question of whether the information they give you is accurate.

A lot of research—ethnographic and survey research alike—is about mapping opinions and attitudes. When people tell you that they approve of how the chief is handling negotiations for their village’s resettlement, or when they tell you that they prefer a particular brand of beer to some other brand, they’re talking about internal states. You pretty much have to take their word for such things.

But when we ask people to tell us about their actual behavior (How many times did you take your baby to the clinic last month? How many times last year did you visit your mother’s village?), or about their environmental circumstances (How many hectares of land do you have in maize? How many meters is it from your house to the well?), we can’t just assume informant accuracy (box 8.9).

We see reports of behavior in our local newspapers all the time: College students today are binge drinking more than they did 5 years ago. Americans are going to church less often than they did a decade ago.

In back of findings like these are questions like these:

Circle one answer:

How many times last month did you consume five or more beers or other alcoholic drinks in a single day?

Never

Once

Twice

Three times

More than three times

How often do you go to church?

Never

Occasionally—once a month or less About once a week More than once a week

BOX 8.9

DIETARY RECALL

Studies of diet and human nutrition mostly rely on informants to recall what they've eaten over the past 24 hours or what they usually eat for various meals. They often produce dreadfully inaccurate results.

C. J. Smith et al. (1996) compared the responses of 575 Pima and Papago Indians (in Arizona) to a 24-hour recall instrument about food intake with responses to a very detailed survey called the Quantitative Food Frequency questionnaire. In the QFF, interviewers probe for a list of regularly consumed foods in a community. Smith et al. also assessed the energy expenditure of 21 people in the research group using the doubly labeled water technique. The DLW technique involves giving people special water to drink—water with isotopes that can be tracked in blood and urine samples—and then testing, over time, their actual intake of nutrients.

The correlation, across the 21 participants, between the energy intake measured by the DLW technique and the energy intake estimated by the informants' responses to the QFF, was 0.48. This correlation is statistically significant, but it means that just 23% (0.482) of the variation in actual energy intake across the 21 people was accounted for by their responses to a very detailed interview about their food consumption. And the correlation of actual energy intake with estimates from the 24-hour recall data was much worse.

R. K. Johnson et al. (1996) also found no useful relation between individual 24-hour recall measurements of energy intake among children in Vermont and measurements of those same children by the DLW technique. But, in the all-is- not-lost department, Johnson et al. found that averaging the data for energy intake across three 24-hour recalls in 14 days (on day 1, day 8, and day 14) produced results that were very similar to those produced by the DLW technique. So, people hover around giving accurate answers to a question about calorie intake and if you get at least three answers for three time windows and take the average, you may get a useful result (Further Reading: measuring food intake and physical activity).

 
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