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Regression coefficients and coding di...
Structural Equation Modeling
posted on Friday, February 01, 2013 - 11:55 am
This seems quite basic but I was puzzled by some analysis in relation to changes in coding directions of a predictor.
I have a continuous outcome variable y, and a predictor variable x which has three levels: 0, 1, 2.
I wanted to flip the direction of x and create a new variable called xr. I recode such that 0 in x now is 2 in xr, and 2 in x becomes 0 xr. Values of 1 remains the same.
I run two regression model, first with x as predictor of y, then with xr as preditor of y. I would expect coefficient of xr has the same magnitude as coefficient of x but with oppoisite signs, right?
But somehow these two are not exactly the same, although the signs are opposite.
I was just wondering, is this normal or might there be something wrong that I did?
Linda K. Muthen
posted on Friday, February 01, 2013 - 2:59 pm
You should get the same coefficient value with the opposite sign. You either made a mistake in the recoding or the sample size changed for some reason.
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