# is it possible to reverse calculate male and female proportion from incidence rate?

#### ArtMart

##### New Member

If i have the total number of acral melanoma = 1413
out of the total cutaneous melanomas = 88 8885.

The cohort study went on for 20 years.

the total incidence rate is 1.8 per 100 000 person-years for Acral melanoma
In acral melanoma, incidence rate for males = 1.9 per 100 000 person-years, and for female = 1.8 per 100 000 person-years

1. can i calculate the actual number of males and females who have acral melanoma?

2. If not, am I allowed to extrapolate the ratio of the incidence rates between male and female to the ratio of the actual proportions between the 2 genders?

thank you

#### hlsmith

##### Less is more. Stay pure. Stay poor.
They don't provide any more decimal places? Are you taking this numbers from a paper, if so please share a link. I didn't follow your second question?

#### ArtMart

##### New Member
Article attached as requested.

2nd qn means if I am to take M:F incidence ratio as 1.9 : 1.8, and then calculate the male and female proportions from 1413 cases, which would be
1.9x + 1.8x = 1413 , x = 381.891..., so that would give me 1.9x = 726 males and 1.8x = 687 females. Am I allowed to do that?

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