# File "Rjack".

# Some data.
x = c(0.417123602237552, 0.357405868126079, 0.711339075583965,
0.946056608809158, 0.173700894461945, 0.105324893025681,
0.310572318034247, 0.120300267590210, 0.80332009983249, 0.347110137576237)

n = length(x)

theta = mean(x)

truevarest = var(x) / n

# Compute the jackknife estimate of variance.
thetam = rep(0,n)
for (i in 1:n) {
        if (i==1)
            xm = x[2:n]
        else if (i==n)
            xm = x[1:(n-1)]
        else
            xm = c(x[1:(i-1)], x[(i+1):n])
        thetam[i] = mean(xm)
}

thetadot = mean(thetam)

jackvarest = (n-1)/n * sum((thetam - thetadot)^2)

print(truevarest)
print(jackvarest)