Ratios (X/Y, e.g. body mass index) are variables with odd distributions. They have no means or moments (e.g. variances, skewness or kurtosis). Thus, my questions are:
- How to compare between (or among) 2 or more groups with ratio variables?
- How to use ratio variables as the independent variable or dependent variable in a regression analyses?
- X/Y is an independent variable: is it better to use X and Y (or 1/Y) as independent variables separately?
- X/Y is a dependent variable: is it better to use X as a dependent variable and Y (or 1/Y) as an independent variable?
- Are most studies on ratios statistically wrong?
- Is the method described by a recent article Error propagation in calculated ratios. Clinical biochemistry, Vol. 40, No. 9-10. (June 2007), pp. 728-734) the way to a solution?