sampfordpi function

Joint inclusion probabilities for Sampford's PPS sampling method

Compute joint inclusion probabilities for Sampford's method of PPS sampling

sampfordpi(sizes,n)

Arguments

• sizes: A vector of the sizes of the units in the population
• n: The sample size

Returns

Returns a matrix with the inclusion probability pi(i) for each unit i in the population and with the joint inclusion probability pi(i,j) of units i and j in position (i,j) in the matrix, where i and j are not equal. Note that the size of the matrix is NxN, where N is the population size.

Note

The function sampford can be used to select a sample using Sampford's method. See the user's guide, pps-ug.pdf, for more information.

Examples

sizes <- c(9,2,5,17,4,21,15,7,4,11,23,23,14)
piij <- sampfordpi(sizes,4)
weights <- 1/diag(piij)  # the weights one would use for estimation