Thank you for commenting and I am glad that the article was helpful.

For calculating the value, P(test positive):

P(test positive) = P(positive|disease)*P(disease) + P(positive|no disease)P(no disease) = (0.99*0.001) + (0.01)*(0.999) = 0.01098

I hope this answers your question :)

Let me know if you have further questions on this or something is not clear..

Scientist (several research publications in prestigious journals such as The Lancet, Brain, Thorax, IEEE Transactions), love writing for meaning & impact…