flightphase {BalancedSampling} | R Documentation |
This is a fast implementation of the flight phase of the cube method. To have a fixed sample size, include the inclusion probabilities as a balancing variable in Xbal
and make sure the inclusion probabilities sum to a positive integer.
flightphase(prob,Xbal)
prob |
vector of length N with inclusion probabilities |
Xbal |
matrix of balancing auxiliary variables of N rows and q columns |
Returns a vector of length N with new probabilities, where at most q are non-integer.
Deville, J. C. and TillĂ©, Y. (2004). Efficient balanced sampling: the cube method. Biometrika, 91(4), 893-912.
Chauvet, G. and TillĂ©, Y. (2006). A fast algorithm for balanced sampling. Computational Statistics, 21(1), 53-62.
## Not run:
# Example 1
# Select sample and check balance
set.seed(12345);
N = 100; # population size
n = 10; # sample size
p = rep(n/N,N); # inclusion probabilities
X = cbind(p,runif(N),runif(N)); # matrix of auxiliary variables
pflight = flightphase(p,X);
# check balance after flight
colSums(X)
colSums(X/p*pflight)
# select final sample as indicators
indicators = landingphase(p,pflight,X);
# check final balance
colSums(X)
colSums(X/p*indicators)
# final sample as indexes
s = (1:N)[indicators==1];
## End(Not run)