deffK | R Documentation |

Compute the Kish design effect due to having unequal weights.

```
deffK(w)
```

`w` |
vector of inverses of selection probabilities for a sample |

The Kish design effect is the ratio of the variance of an estimated mean in stratified simple random sampling without replacement (*stsrswor*) to the variance of the estimated mean in *srswor*, assuming that all stratum unit variances are equal. In that case, proportional allocation with equal weighting is optimal. `deffK`

equals `1 + relvar(w)`

where `relvar`

is relvariance of the vector of survey weights. This measure is not appropriate in samples where unequal weighting is more efficient than equal weighting.

numeric design effect

Richard Valliant, Jill A. Dever, Frauke Kreuter

Kish, L. (1965). *Survey Sampling*. New York: John Wiley & Sons.

Kish, L. (1992). Weighting for unequal Pi. *Journal of Official Statistics*, 8, 183-200.

Valliant, R., Dever, J., Kreuter, F. (2018, chap. 14). *Practical Tools for Designing and Weighting Survey Samples, 2nd edition*. New York: Springer.

`deff`

, `deffCR`

, `deffH`

, `deffS`

```
data(nhis)
w <- nhis$svywt
deffK(w)
```

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