Testing homogenity of variances

The statistician Box once said “To make a preliminary test on variances is rather like putting to sea in a rowing boat to find out whether conditions are sufficiently calm for an ocean liner to leave port” (1953,Biometrika, 40, p.333).

An intersting debate I have found on net

I have found a debate through some researchers on the net, it was interesting to read
http://challengingbell.blogspot.com.tr/2015/05/further-numerical-validation-of-joy.html
https://www.researchgate.net/publication/285439686_Macroscopic_Observability_of_Spinorial_Sign_Changes_A_Simplified_Proof#feedback/235509

Fundamentals of Biostatistics

A good book to go for introduction to Biostatistics is by Bernard Rosner, Fundamentals of Biostatistics.