# sampsizeval

The purpose of **sampsizeval** is to perform sample size
calculations for the validation of risk models for binary outcomes.

## Installation

The development version can be installed from GitHub with:

```
# install.packages("devtools")
devtools::install_github("mpavlou/sampsizeval")
```

## Example

This is an example of a sample size calculation to validate a risk
model for a binary outcome. The anticipated values of the outcome
prevalence and the C-statistic are p=0.1 and C=0.75, respectively.

`{r example} library(sampsizeval)`

The target is to calculate the size of the validation data so as to
estimate the C-statistic, the Calibration Slope and the Calibration in
the Large with sufficient precision. In this example, the required
precision is reflected by a SE of the estimated C-statistic of at most
0.025, and SE of the estimated Calibration Slope and Calibration in the
Large of at mos 0.1.

`sampsizeval(p=0.1, c=0.75, se_c=0.025, se_cs =0.1, se_cl = 0.1)`

The recommended sample size is 1536 observations.