How to conduct a ROC curve for performance of PCR?

17 June 2015 1 5K Report

I have a dataset of asymptomatic carrier parasite that I tested for parasite presence using 4 different assays (microscopy, RDT, pcr and RT-PCR) I need to conduct a ROC curve to determine the cutoff point for my CT value similar to this paper http://www.biomedcentral.com/content/pdf/1475-2875-9-269.pdf

however I'm now sure how can I determine true positive from true negative since all my study population were asymptomatic?

Maha Adel Elbadry

Thanks Jochen, I wonder if you have an article that would explain that. I have standardized by RT-PCR assay using laboratory based culture after synchronizing the life stage mimicing human condition. and I did do a series of dilution based on the number of parasites i initially loaded in my reaction. Do you think I can use that as a standard gold method to compare results from field?

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