1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
|
deff <- function(y, cluster)
{
ss <- function(x)
{
n <- length(x)
xbar <- sum(x) / n
sum((x - xbar)^2)
}
if(!is.factor(cluster)) cluster <- as.factor(cluster)
cluster <- unclass(cluster)
s <- !is.na(cluster + y)
y <- y[s]
cluster <- as.integer(cluster[s])
n <- length(y)
sst <- ss(y)
sses <- tapply(y,cluster,ss)
k <- length(sses)
R2 <- 1 - sum(sses) / sst
Fstat <- R2 * (n - k) / (1 - R2) / k
g <- (Fstat - 1.) * k / n
rho <- if(R2 == 1.) 1. else g / (1. + g)
ng <- table(cluster)
B <- sum(ng^2) / n
deff <- 1 + (B - 1) * rho
c(n=n, clusters=k, rho=rho, deff=deff)
}
|
