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sspam
2009 Feb 12
0
Comparing slopes in two linear models
...t2)$coefficients
db <- (s1[2,1]-s2[2,1])
#### TEST DEGREES OF FREEDOM
n1 <- fit1$df.residual
n2 <- fit2$df.residual
n <- n1 + n2
### Pooled Variance ####
ssx1 <- var(df1$CDI) * (n1+1)
ssx2 <- var(df2$CDI) * (n2+1)
RSS1 <- anova(fit1)[2,2]
RSS2 <- anova(fit2)[2,2]
sspvm <- ( RSS1 + RSS2 ) / n
sd1_2 <- sqrt( sspvm/ssx1 + sspvm/ssx2 )
td <- db/sd1_2
2*pt(-abs(td), n)
}
Zar(dP, dHT)
[1] 0.4040566
Is there anything wrong with the function I wrote?
Assuming that there is nothing wrong with the function I wrote, I'd like
to know why R dos not follow t...