In Grant 1986
, it says:
For this analysis the absolute fitness of an individual id scored as 0 if it disappeared and 1 if it survived, and these scores are then converted to relative fitness values by dividing them by the mean absolute fitness.
Grant, P. R. 1986. Ecology and Evolution of Darwin's Finches
If we have this dataset (for example):
id x1 x2 x3 x4 x5
1 1 0 1 0 0 0
2 2 0 0 1 1 0
3 3 1 0 1 1 0
4 4 1 0 1 1 1
5 5 1 0 1 0 0
6 6 0 0 0 0 1
Imagine that id is a column of individuals and the rest (x#) are the absolute fitness. Then, how would you calculate the relative fitness? For an example, what would be the relative fitness between x3 and x4? X1 is the first event of capture. I.e. I went on the field and capture birds for examples and noted who was there (0). I went on the field on X2, X3, etc. and noted which bird was there.