With this article from the CDC, I'm creating a log-log plot of all percentiles for the weight of men aged 25-34 (page 32) against all percentiles for the height of men aged 25-34 (page 33).
So the data looks something like...
percentile | log(height) | log(weight)
99 | 4.3307 | 5.5134
95 | 4.301 | 5.407
90 | 4.286 | 5.338
80 | 4.268 | 5.273
.
.
.
My linear regression equation ended up with a slope of 4.0527, but I know the slope should be somewhere close to 2 from previous analyses for other datasets.
Is the misconception with this approach that the x
th percentile observation in height is NOT necessarily related to the x
th percentile observation in weight. Therefore, the ordered pairs on the log-log plot are incorrect?
I found a similar question here, but the author is only plotting percentiles for the predictor variable and not the response variable.