allocate | R Documentation |
This is a function to compute the optimum allocation for a stratified random sampling design.
allocate(Ni, si, ci = rep(1, length(Ni)), c0 = 0, ct = NA, ev = NA)
Ni |
Vector of total number of sampling units in each stratum. |
si |
Vector of the standard deviation for each statum |
ci |
Vector of the cost per unit for each stratum. |
c0 |
Overhead survey cost. |
ct |
Total cost for the survey. |
ev |
Variance for the estimator of the population mean. |
The solution is based choosing the overall sample size and the sample sizes for each stratum to minimize the estimator variance for a fixed cost, or to minimize the cost for a fixed estimator variance. The solution assumes the usual estimator for the for the population mean and a variance based on a finite sample design-based approach. The total cost of the survey is assumed to be the overhead cost plus a per-unit cost for each sampled unit. See Cochran (1977) for details.
A list of a vector of the proportion of units to sample from each stratum, a vector of sample sizes for each stratum, total sample size, estimator variance, and total survey cost. If neither the estimator variance (ev
) or the total cost (ct
) are specified then only the proportions can be computed.
Cochran, W. G. (1977). Sampling techniques (3rd Edition). New York: Wiley.
# sampling fractions only
allocate(Ni = c(155,62,93), si = c(5,15,10), ci = c(9,9,16))
# allocation for estimator variance fixed at 1
allocate(Ni = c(155,62,93), si = c(5,15,10), ci = c(9,9,16), ev = 1)
# allocation for total survey cost fixed at 500
allocate(Ni = c(155,62,93), si = c(5,15,10), ci = c(9,9,16), ct = 500)
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