Stratified probability-proportional-to-size (PPS) sampling using permanent random numbers. Can also be used for non-stratified PPS using a dummy stratum taking the same value for each object.
Usage
pps(df, stratid, nsamp, prn, size)
Value
Copy of the input data frame together with the boolean variable sampled, as well as a numeric variable lambda containing the estimated first-order inclusion probabilities and the numeric variable $$Q = \frac{prn(1 - lambda)}{lambda(1 - prn)}$$ that determines which elements are sampled.
Arguments
df
Data frame containing the elements to sample from.
stratid
Variable in df containing the strata.
nsamp
Variable in df containing the sample sizes.
prn
Variable in df containing the permanent random numbers.