Displaying 2 results from an estimated 2 matches for "ssx1".
Did you mean:
ss1
2004 Feb 19
1
Comparing two regression slopes
...lm(y~x, df2)
> s2 <- summary(fit2)$coefficients
> db <- (s2[2,1]-s1[2,1])
> sd <- sqrt(s2[2,2]^2+s1[2,2]^2)
> df <- (fit1$df.residual+fit2$df.residual)
> td <- db/sd
> 2*pt(-abs(td), df)
[1] 0.8757552
Sokal & Rholf
> n <- length(df1$x)
> ssx1 <- var(df1$x)*(n-1) # sums of squares
> ssx2 <- var(df2$x)*(n-1)
> ssy1 <- var(df1$y)*(n-1)
> ssy2 <- var(df2$y)*(n-1)
> sxy1 <- cor(df1$x,df1$y)*(n-1)
> sxy2 <- cor(df2$x,df2$y)*(n-1)
> d2xy1 <- ssy1 - sxy1^2/ssx1 # unexplained
> d2xy2...
2009 Feb 12
0
Comparing slopes in two linear models
...arCDI)~log(df1$CDI) )
fit2 <- lm( log(df2$varCDI)~log(df2$CDI) )
s1 <- summary(fit1)$coefficients
s2 <- summary(fit2)$coefficients
db <- (s1[2,1]-s2[2,1])
#### TEST DEGREES OF FREEDOM
n1 <- fit1$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 th...