Suggested answer to exercise: House dust mite and wheeze in Ethiopia, 4

Question 4: What do they mean by the odds ratio per quartile?

Suggested answer

Usually we would get the odds ratio per unit of the measurement. What these authors have done is to recode the variable as 1 if below the first quartile, 2 if between the first and second, 3 if between the second and third, and 4 if above the third quartile. They have then used this variable as the predictor. The odds ratio estimate is then the odds ratio for a difference in house dust mite exposure from one quarter of the scale to the next. Personally, I donít like this idea much.

I warned you that this was really tough!

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Last updated: 31 July, 2006.

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