[R] Data manipulation

[Johannes Huesing]

mathijsdevaan <mathijsdevaan at gmail.com> [Sat, Feb 12, 2011 at 03:00:18PM CET]:
> 
> Hi,
> 
> I have a dataset with info on individuals (B) that have been involved in
> projects (A) during multiple years (C). The dataset contains three columns:
> A, B, C. Example:
>    A  B  C
> 1 1  a  1999
> 2 1  b  1999
> 3 1  c  1999
> 4 2  c  2001
> 5 2  d  2001
> 6 3  a  2004
> 7 3  b  2004
> 
> I am interested in the average tenure of all individuals for each project
> (assuming that the tenure of an individual = 0 in the first project this
> individual is involved in). So based on the data above:
>   A  D
> 1 1  0
> 2 2  1
> 3 3  5
> 
> where D = average project tenure. How do I do this?
> 

I am not getting how you arrive at D calculating an "average".
Could you write down the arithmetic operations involved?


-- 
Johannes Hüsing               There is something fascinating about science. 
                              One gets such wholesale returns of conjecture 
mailto:johannes at huesing.name  from such a trifling investment of fact.                
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