Bartlett' test
Silvano wrote:
Hi, I have an experiment with 5 treatments, of which 2 with 10 repetitions and 2 with 7 replications. I conducted the test of Bartlett step-by-step and compared with the value calculated directly by the R and the values are different. Anyone know tell me why?
The first term in M looks wrong when group sizes differ, but it would be much easier to check if you gave the actual group variances. (and PLEASE don't hijack other threads. This has nothing to do with kernlab's ksvm!)
#------------------- n = length(trat) I = 4 (M = 2.3026*((n-I)*log10(mean(tapply(valor,trat,var))) - (9*log10(vari[1])+9*log10(vari[2])+6*log10(vari[3])+6*log10(vari[4])))) (C = 1 + 1/(3*(4-1))*((1/9 + 1/9 + 1/6 + 1/6) - 1/(9+9+6+6))) (B = M/C)
B
1.748670
qchisq(.05, 3, lower.tail=F) # Valor tabelado
[1] 7.814728
#-----------------------------------------
# Teste de Bartlett de forma direta no R -
#-----------------------------------------
bartlett.test(valor,trat)
Bartlett test of homogeneity of variances
data: valor and trat
Bartlett's K-squared = 0.7845, df = 3, p-value =
0.8532
O__ ---- Peter Dalgaard ?ster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907