rsu.sep.rs2st {epiR} R Documentation

## Surveillance system sensitivity assuming representative two-stage sampling

### Description

Calculates the surveillance system sensitivity for detection of disease assuming two-stage sampling (sampling of clusters and sampling of units within clusters), imperfect test sensitivity and perfect test specificity.

### Usage

```rsu.sep.rs2st(H = NA, N = NA, n, pstar.c, pstar.u, se.u = 1)
```

### Arguments

 `H` scalar, integer representing the total number of clusters in the population. Use `NA` if unknown. `N` vector, integer representing the number of units within each cluster. Use `NA` if unknown. `n` vector, integer representing the number of units tested within each cluster. `pstar.c` scalar, numeric (0 to 1) representing the cluster-level design prevalence. `pstar.u` scalar, numeric (0 to 1) representing the unit-level design prevalence. `se.u` scalar, numeric (0 to 1), representing the sensitivity of the diagnostic test at the individual unit level.

### Value

A list comprised of:

 `se.p` the surveillance system (population-level) sensitivity of detection. `se.c` the cluster-level sensitivity of detection. `se.u` the unit-level sensitivity of detection. `N` the number of units within each cluster, as entered by the user. `n` the number of units tested within each cluster, as entered by the user.

### Note

If `pstar.c` is not a proportion `N` must be provided and `N` must be greater than `n`.

### Examples

```## EXAMPLE 1:
## A study is to be conducted to confirm the absence of enzootic bovine
## leukosis disease in your country. Four herds are to be sampled from a
## population of 500 herds. There are 550, 250, 700 and 200 cows in each of
## the four herds. From each of the four herds 30 animals are to be sampled.
## The design prevalence for this study is set to 0.01 at the herd level
## and if a herd is positive for leukosis the individual animal level
## design prevalence is set to 0.10. Assuming a test with diagnostic
## sensitivity of 0.98 will be used, what is the sensitivity of
## disease detection at the population and cluster (herd) level?

rsu.sep.rs2st(H = 500, N = c(550,250,700,200), n = rep(30, times = 4),
pstar.c = 0.01, pstar.u = 0.10, se.u = 0.98)

## The population level sensitivity of detection is 0.037. The cluster level
## sensitivity of detection ranges from 0.950 to 0.958.

```

[Package epiR version 2.0.31 Index]