Displaying 3 results from an estimated 3 matches for "epsihf".
2005 Feb 23
1
H-F corr.: covariance matrix for interaction effect
...S)
# n - number of measurements (i.e. number of rows in original matrix)
epsi.GG.HF <- function (S,k,n) {
D <- (k^2 * (mean(S) - mean(diag(S)))^2)
N1 <- sum(S^2)
N2 <- 2 * k * sum(apply(S, 1, mean)^2)
N3 <- k^2 * mean(S)^2
epsiGG <- D / ((k - 1) * (N1 - N2 + N3))
epsiHF <- (n * (k-1) * epsiGG - 2) / ((k-1) * ((n-1) - (k-1)*epsiGG))
c(epsiGG,epsiHF)
}
# three factors, facROI,facCond,facSubj
# facROI,facCond are main effects, facSubj is "repeatedness"
# G-G and H-F corrections for a main effect
# we do the gghf stuff for the ROI, which means ROIs i...
2005 Feb 23
1
H-F corr.: covariance matrix for interaction effect
...S)
# n - number of measurements (i.e. number of rows in original matrix)
epsi.GG.HF <- function (S,k,n) {
D <- (k^2 * (mean(S) - mean(diag(S)))^2)
N1 <- sum(S^2)
N2 <- 2 * k * sum(apply(S, 1, mean)^2)
N3 <- k^2 * mean(S)^2
epsiGG <- D / ((k - 1) * (N1 - N2 + N3))
epsiHF <- (n * (k-1) * epsiGG - 2) / ((k-1) * ((n-1) - (k-1)*epsiGG))
c(epsiGG,epsiHF)
}
# three factors, facROI,facCond,facSubj
# facROI,facCond are main effects, facSubj is "repeatedness"
# G-G and H-F corrections for a main effect
# we do the gghf stuff for the ROI, which means ROIs i...
2007 Jun 24
2
ANOVA non-sphericity test and corrections (eg, Greenhouse-Geisser)
...Feldt correction
# The Greenhouse-Geisser epsilon tends to underestimate
# epsilon when epsilon is greater than 0.70 (Stevens, 1990).
# An estimated e=0.96 may be actually 1. Huynh-Feldt
# correction is less conservative. The Huynh-Feldt
# epsilon is calculated from the Greenhouse-Geisser epsilon,
epsiHF <- (n * (k-1) * epsi - 2) / ((k-1) * ((n-1) - (k-1)*epsi))
PepsiHF <- 2 * (1 - pf(Fvalue, df1=epsiHF*(k-1),
df2=epsiHF*(k-1)*(n-1) ) )
# MANOVA (and multivariate tests) may be better if the
# Greenhouse-Geisser and the Huynh-Feldt corrections do not agree,
# which may happen when epsilon dr...