# 'e' in expected values in Poisson

#### sarahharding

##### New Member
Using this example (see below) could someone please tell me what the 'e' symbol stands for and how one would work out the expected values manually.

'log(λi) = 1.65 + 0.43 × xi
where xi = 1 for a female, and xi = 0 for a male.

Poisson Regression

Using this example, we see that for a female
λFemale = e1.65+0.43 = 8.004
and for males
λMale = e1.65 = 5.2

In other words, the expected value for females is 8.2 and for
males it is 5.2.'

Thanks

#### Mean Joe

##### TS Contributor
e is Euler's number, approximately 2.71828.

You need to exponentiate, e.g. 2.71828 ^ (1.65+0.43) = 8.004

You should actually be able to find the e on a calculator (if that calculator also has pi), instead of typing 2.71828...