positive/positiver

22:08 Jan 1, 2017 

You are quite welcome Denise. Happy New Year to all, friends and colleagues!

14:42 Jan 1, 2017 

Hi Charles,
Thanks so much for posting this response - your urine drug test reference is hugely helpful to me for understanding the idea of "making a test positive." And I appreciate your further comment supporting, in this context, "confirming" the positive result. Thanks for all the help you've provided to me this past year!

12:51 Jan 1, 2017 

I've had another look at this and I think I was wrong and that "positiver" must mean confirm here. I disagreed with this because as far as I knew "positiver un test" normally means to give/produce a positive result in a test. That is, to say that the presence of a substance or some other circumstance "positive un test" means that it causes the test to give a positive result. For example, on urine tests for drug use:
"L'inhalation passive de fumée n'est pas suffisante pour positiver le test. Un test positif évoque avec une très forte probabilité une consommation active."
http://www.cbm25.fr/depistage-drogue-urinaire

That was what I thought Dr Manu meant by "make the tests positive". But I must admit that it doesn't make sense to say that LC-MS produces a positive result in an immunochemical test; it must mean confirming a positive result: turning a doubtful or questionable result into a firm positive, as you might say. So "confirm" seems best in practice and I withdraw my comment. Sorry for the confusion; I didn't look carefully enough at the context. Apologies to Dr Manu as well. Happy New Year!

19:14 Dec 31, 2016 

@ Charles: Thanks for adding your comment to Dr Manu's answer. When I was initially thinking "positiver" might mean "confirm," I was thinking that a rapid immunochemical test might need to be confirmed by a more sensitive/specific assay. You said you disagree with this, but that "make the tests positve" is more or less OK. I'm not sure if you'll see this post, but if so, could you explain what you mean by "make the test positive"? LC-MS/MS "makes" most immunochemical tests "positive"? I'm definitely missing or misunderstanding something. Thank you Charles!