# CVcalc2: Coefficient of variation of an estimated total in a 2-stage... In PracTools: Tools for Designing and Weighting Survey Samples

 CVcalc2 R Documentation

## Coefficient of variation of an estimated total in a 2-stage sample

### Description

Compute the coefficient of variation of an estimated total in a two-stage design. Primary sampling units (PSUs) can be selected either with probability proportional to size (pps) or with equal probability. Elements are selected via simple random sampling (srs).

### Usage

```CVcalc2(V=NULL, m=NULL , nbar=NULL, k=1, delta=NULL, Bsq=NULL, Wsq=NULL)
```

### Arguments

 `V` unit relvariance of analysis variable in the population `m` number of sample PSUs `nbar` number of sample elements per PSU `k` ratio of B^2 + W^2 to V. Default value is 1. `delta` measure of homogeneity equal to B^2/(B^2 + W^2) `Bsq` unit relvariance of PSU totals `Wsq` within PSU relvariance

### Details

`CVcalc2` computes the coefficient of variation of an estimated total for a two-stage sample. PSUs can be selected either with varying probabilities and with replacement or with equal probabilities and with replacement. Elements within PSUs are selected by simple random sampling. The CV formula is appropriate for approximating the relvariance of the probability-with-replacement (pwr)-estimator of a total when the same number of elements is selected within each sample PSU. See Sections 9.2.1–9.2.3 of Valliant, Dever, and Kreuter (2013) for details of formulas.

### Value

Value of the coefficient of variation of an estimated total

### Author(s)

Richard Valliant, Jill A. Dever, Frauke Kreuter

### References

Cochran, W.G. (1977, pp.308-310). Sampling Techniques. New York: John Wiley & Sons.

Saerndal, C.E., Swensson, B., and Wretman, J. (1992). Model Assisted Survey Sampling. New York: Springer.

Valliant, R., Dever, J., Kreuter, F. (2018, sect. 9.2.1). Practical Tools for Designing and Weighting Survey Samples, 2nd edition. New York: Springer.

`CVcalc3`
```CVcalc2(V=1, m=20 , nbar=5, k=1, delta=0.05)