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

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

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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 don’t 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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