PoissonSample

PoissonSample(pi, prn=None)

Ordinary Poisson sampling.

Parameters

pi : InclusionProb

Inclusion probabilities for units in the population.

prn : ArrayLike = None

Permanent random numbers. Should be a flat array of values, the same length as pi, distributed uniform between 0 and 1. The default draws a sample without permanent random numbers.

Attributes

units : Array

Indices for units in the sample.

weights : Array

Design weights for units in the sample.

take_all : Array

Take-all units in the sample.

take_some : Array

Take-some units in the sample.

prn : Array

Random numbers used for drawing the sample.

References

Ohlsson, E. (1998). Sequential Poisson Sampling. Journal of Official Statistics, 14(2): 149-162.

Examples

import numpy as np
import pysps

x = np.arange(10)
pi = pysps.InclusionProb(x, 6)

# Draw an ordinary Poisson sample using permanent random numbers.

prn = np.random.default_rng(54321).uniform(size=10)
sample = pysps.PoissonSample(pi, prn)
sample.units

array([3, 4, 5, 6, 7, 8, 9])