prevalence ratio question

Question

I understand that prevalence ratio is

                            Number of people in sample with characteristic
        Prevalence ratio =  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
                                 Total # of people in sample

https://www.nimh.nih.gov/health/statistics/what-is-prevalence

My question is does the denominator in this formula include the numerator ? Are the number of people with disease included in the Total # of people in the sample ?

Aside: [Why do some researchers use the oxymoron "prevalence *rate*"?](https://stats.stackexchange.com/questions/493757/why-do-some-researchers-use-the-oxymoron-prevalence-rate) — Alexis, Jan 14 '22 at 19:18

score 3 · Accepted Answer · answered Jan 14 '22 at 19:22

Yes. The denominator includes the numerator.

A prevalence can be understood as measuring the proportion of people in a population sharing some characteristic. So:

$$\text{Prevalence of }X\text{ in pop.} = \frac{\text{No. people with }X\text{ in pop.} }{\text{No. people with }X \text{ in pop.} + \text{No. people without }X \text{ in pop.}}$$

prevalence ratio question

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