I am using a continuous variable of body mass index. I checked the distribution using statistical tests and determined it is not normally distributed. I think these results are driven by outliers, there is a huge number of them. How can I deal with outliers? I am going to use this variable as a dependent variable for a linear regression.
$\begingroup$
$\endgroup$
2
-
$\begingroup$ Relevant discussions here: stats.stackexchange.com/questions/2492/… stats.stackexchange.com/questions/86835/… stats.stackexchange.com/questions/163642/… $\endgroup$– AdamOCommented Mar 20, 2018 at 19:50
-
1$\begingroup$ BMI is useless. Do you have a measure of waist circumference instead? BMI is no longer a risk factor for metabolic syndrome after adjusting for waist circumference while waist circumference remains a risk factor. $\endgroup$– AdamOCommented Mar 20, 2018 at 19:51
Add a comment
|
1 Answer
$\begingroup$
$\endgroup$
5
First, BMI is a really terrible measure.
Second, nothing in OLS regression requires that the DV be normal. The errors are assumed to be normal. However, outliers may be a problem but this can be dealt with by using e.g. quantile regression.
answered Mar 20, 2018 at 19:43
-
2$\begingroup$ It's interesting Pearson rejected BMI = weight / height^3 (thus BMI as a weight-density) in favor of weight / height^2 because it made his data look more normal. He failed to project what modern agriculture would do to waistlines. $\endgroup$– AdamOCommented Mar 20, 2018 at 19:51
-
$\begingroup$ I am using a multiple linear regression for gender age and ethnicity as independent variables and one of the assumptions is normality of data. If i was using a logistic regression it wouldnt be an issue i think. What am asking is possible paths that i can use. $\endgroup$ Commented Mar 20, 2018 at 19:56
-
$\begingroup$ No, normality of the data is not an assumption of linear regression.That is incorrect. $\endgroup$ Commented Mar 20, 2018 at 20:13
-
$\begingroup$ Ok thanks. i thought that normal distribution is related to standard error mean which for my bmi variable is 0.091. Is that acceptable? $\endgroup$ Commented Mar 20, 2018 at 20:24
-
$\begingroup$ It's impossible to say whether that is acceptable. $\endgroup$ Commented Mar 20, 2018 at 21:31