₦airaland Forum

jaephoenix:
Probability of having HIV in a region is different from prevalence of a the disease. 2 different entities. You need to get your epidemiology right

And how does this appear I'm talking about epidemiology? Take it easy, dude. This is just maths, not epidemiology. It doesn't carry with it all those intricacies you have in your post above. Prevalance in Bayesian statistics is different from prevalence in epidemiology.

This is really nicely said, though lacking in some detail. The probability isn't exactly 1%. It's a little higher, but it's no more than 2-3%. And as you have rightly pointed out, the consequence is a significant shift in people's experiences which often leads them into thinking a miracle is at work. Quite the contrary!

Say the prevalence of HIV in Nigeria is probably no more than 1.5%. This is the probability of having HIV and it significantly affects the probability of testing positive given that you have the disease. Let's call that P(D). Therefore, P(not D)=0.985.

If the sensitivity of the test, like you've pointed out is, 99%, then it means the test is wrong 1% of the time. Let's say the specificity of the test is 97%, which means if someone is not HIV positive, then the HIV test gets that right 97% of the time. You can go from this to obtaining P(D | HIV+) which is the probability that you have HIV given that you test positive. That's (0.99 x 0.015)/(0.99 x 0.015 + 0.97 x 0.985) = 0.0153.

That equals just about 1.53% probability that you have HIV given that you test positive. This is the posterior probability in Bayes theorem. So, the chance is not even great at all and the person may actually not have HIV at all.

So your observation is correct. Many go from here into panick mode. Only by taking the test a second time and using this as your new prior probability does the posterior increase. This is why a second test is recommended after doing a first.

Before extensive use of Bayes theorem, many people didn't understand this. Not even doctors who conducted the test, so it's not totally unreasonable to have many still ignorant about it.

TastyFriedPussy:
Person go suffer to see money to buy laptop
still suffer to see money buy course
still suffer to see money take buy data to dey watch and follow the course(if you no see money, inconsistency go come dey set in)
This life just tire me

I Honestly,honestly,regret being born into this continent...
God dey....

I don't see why you should feel demotivated. Always think about the reality that there are those who have done it even in the worst conditions. That's what's important. There are single moms who have had to juggle their kid, their job, and then coding, and who still succeeded at this. My advice to you is to keep your eye on the goal.