Dear Xavier
You problem comes from using attach(). Do not do that, it usually ends
in tears. Either use the data parameter to the functions which support
it or look at with() and within().
On 28/10/2017 21:11, CHIRIBOGA Xavier wrote:
Dear colleagues,
How can I do to "relevel" the intercept?
I need that the treatment "Db" be the intercept, and have p-values for the
comparisons with the others treatments.
I used the function "relevel" but it did not work out to have what I want.
Thanks for your help,
Xavier
T1 <- read.table(file.choose(), h=T)
head(T1)
treatment replicate Time Ebcg
1 CHA0+Db 1 1 9681172
2 CHA0+Db 2 1 5599000
3 CHA0+Db 3 1 10280480
4 CHA0+Db 4 1 1004526
5 CHA0+Db 5 1 12942018
6 CHA0+Db 6 1 7478773
attach(T1)
summary(T1)
treatment replicate Time Ebcg
CHA0 :6 Min. :1.000 Min. :1 Min. : 0
CHA0+Db:9 1st Qu.:2.750 1st Qu.:1 1st Qu.: 1000922
Db :9 Median :4.500 Median :1 Median : 4044094
Healthy:9 Mean :4.625 Mean :1 Mean : 5699717
PCL :6 3rd Qu.:6.250 3rd Qu.:1 3rd Qu.: 7785782
PCL+Db :9 Max. :9.000 Max. :1 Max. :24736254
hist(Ebcg)
treatment<-relevel(treatment,ref="Db")
mT1<-lm(sqrt(Ebcg)~treatment,data=T1)
summary(mT1)
Call:
lm(formula = sqrt(Ebcg) ~ treatment, data = T1)
Residuals:
Min 1Q Median 3Q Max
-1748.12 -540.19 0.97 545.14 1949.22
Coefficients:
Estimate Std. Error t value
Pr(>|t|)
(Intercept) 532.5 384.4 1.385
0.173296
treatmentCHA0+Db 2048.5 496.3 4.128 0.000170 ***
treatmentDb 2491.9 496.3 5.021 9.93e-06
***
treatmentHealthy 1215.6 496.3 2.450 0.018552 *
treatmentPCL 120.4 543.6 0.221 0.825816
treatmentPCL+Db 2098.9 496.3 4.229 0.000124 ***
---
Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
Residual standard error: 941.6 on 42 degrees of freedom
Multiple R-squared: 0.5206, Adjusted R-squared: 0.4635
F-statistic: 9.121 on 5 and 42 DF, p-value: 6.227e-06
Xavier Chiriboga M.
PhD Candidate
Fundamental and Applied Research in Chemical Ecology Lab.
Institute of Biology
University of Neuchatel
Website: https://www.unine.ch/farce/home/membres/xavier-chiriboga.html
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--
Michael
http://www.dewey.myzen.co.uk/home.html
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