Thanks for the answer, but it's still don't work.
What I get for each genotype look like this:
$`02-02`
Welch Two Sample t-test
data: slength[, 6] by slength[, 3]
t = 1.6262, df = 682.116, p-value = 0.1044
alternative hypothesis: true difference in means is not equal to 0
95 percent confidence interval:
-0.1336494 1.4224993
sample estimates:
mean in group d mean in group w
2.419450 1.775025
For each of the genotypes all the data is tests, not just the data for the
unique genotype.
Peter Dalgaard wrote:
>
> Imri wrote:
>> My data (slength) look like this:
>> Plant Block Treat Genotype Source MPH
>> 1 1 1 w 05-AZM sp 160 NA
>> 2 2 1 w 12-50 463 NA
>> 3 3 1 w 12-51 sp 150 0.0508982
>> 4 5 1 w 29-42 567 0.9017094
>> 5 6 1 w KNG-KNG 811 NA
>> 6 7 1 w 02-02 1 NA
>>
>> Treat column has w or d for each Plant(row). I wont to do t.test of
>> MPH~Treat for each of the genotypes (128 total). I tried :
>>
>> t.tests<-by(slength, slength[,4], function(x)
>> t.test(slength[,6]~slength[,3]))
>>
>> but it is not what I need.
>> Do you have any ideas?
>> Thanks
>> Imri
>>
>
> Your function(x)... doesn't depend on x! Try
>
> ...t.test(MPH~Treat, data=x)
>
> --
> O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B
> c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
> (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
> ~~~~~~~~~~ - (p.dalga...@biostat.ku.dk) FAX: (+45) 35327907
>
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