How does multivariate analysis calculate odds ratio of image ?

I have read the following article.. http://www.dermoscopy.org/consensus/2d.asp Here,It presents 7 point checklist for determining melanoma.It also shows odds ratio of each point. I have read one reasearch papers where they calculates odd ratios using multivariate analysis.But i cannot understand the procedure. I will be thankful if anyone tell me what should i do to calculate the odds ratio of the 7 points ?

[Sadia Iffat]

please help anyone.Dont ignore

[Sadia Iffat]

 John D'Errico
what is the reason for being closed? i didnot want code.I wanted some idea