[R] correlation tab
(Ted Harding)
ted.harding at nessie.mcc.ac.uk
Fri Apr 27 12:20:06 CEST 2007
On 27-Apr-07 09:38:55, elyakhlifi mustapha wrote:
> hello,
> I know how to use the function "cor" to do correlation frame
> but it remains a problem because I wanna calculate correlation
> between vector with differents dimensions it is possible?
> for exemple my data :
>
>> V
> [[1]]
> [1] 97 104 103 98 99 92 99 99 98 87 95 101 91 104
> 98 96 84 97 92 104 97
> [[2]]
> [1] 102 100 82 106 85 97 101 99 90 101 97 93 100 99
> 92 90 102 94 99 104
> [[3]]
> [1] 98 95 104 96 104 86 100 91 94 95 99 100 95 95
> 104 98 97 99 94 100 94
>
> length(V[[1]]) = length(V[[3]]) = 21 but length(V[[2]]) = 20
Correlation only makes sense in a context where each element of
one vector used in the correlation is associated with a single
corresponding element of the other vector (think in terms of
simulataneous observations of different variables on an item:
so for instance V1[1] would be the obversevation of variable V1
on item 1, V2[1] the observation of variable V2 on item 1, etc.;
so V1[i], V2[i] and V3[i] are the observations of variables
V1, V2, V3 on item i).
So now it is up to you to identify what the association is
between the elements of your V[[1]], V[[2]] and V[[3]].
It may be that your "short" vector V[[2]] is simply missing
an observation on one item. In which case, the simplest approach
is to omit the corresponding element from V[[1]] and V[[3]],
and calculate the correlation from the remainder, assuming of
course that their elements are indeed associated in the way
described above.
Hoping this helps,
Ted.
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E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
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Date: 27-Apr-07 Time: 11:19:40
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