Roc Curve STATA

[Emanuele Spina]

Hi guys,

i have obtained this graph with command roctab x y, graph.

On this graph i have sensitivity starting from 0 and rising to 100; usually i read graphic with sensitivity on y axis starting from 100 and rising to 0; conversely specificity seems correct.

Moreover, values "0", that corresponds to 100 sensitivity and 0 specificity is on the right top corner of the graph, and it should be on the bottom left corner. How can i adjust this?

Thank you

[Leonardo Guizzetti]

I don't quite understand what you are asking for, but I think you might be misunderstanding the conventions of the ROC curve and what the axis labels mean. The ROC curve (in medicine and epidemiology at least) is customarily a plot of increasing sensitivity (or true positive rate) on the y-axis and increasing 1-specificity (or false positive rate) on the x-axis. This is what -roctab, graph- made for you.