This robust method is used to calculate the reference interval on small sample
size (below to 120 observations).

## Usage

`robustRI(x, ind = 1:length(x), conf.level = 0.95, tol = 1e-06)`

## Arguments

- x
(`numeric`

)

numeric measurements from target population.

- ind
(`integer`

)

integer vector for boot process, default is all elements
in `x`

.

- conf.level
(`numeric`

)

significance level for the internal t statistic.

- tol
(`numeric`

)

tolerance for when the iterative process can be stopped.

## Value

a vector of robust reference interval

## References

This robust algorithm is referring to CLSI document EP28A3.

## Examples

```
# This example data is taken from EP28A3 Appendix B. to ensure the result is in accordance.
x <- c(8.9, 9.2, rep(9.4, 2), rep(9.5, 3), rep(9.6, 4), rep(9.7, 5), 9.8, rep(9.9, 2), 10.2)
robustRI(x)
#> [1] 9.049545 10.199396
```