samplesize {biotools} | R Documentation |

## Minimum Sample Size

### Description

Function to determine the minimum sample size for calculating a statistic based on its the confidence interval.

### Usage

```
samplesize(x, fun, sizes = NULL, lcl = NULL, ucl = NULL,
nboot = 200, conf.level = 0.95, nrep = 500, graph = TRUE, ...)
```

### Arguments

`x` |
a numeric vector. |

`fun` |
an objective function at which to evaluate the sample size; see details. |

`sizes` |
a numeric vector containing sample sizes; if |

`lcl` |
the lower confidence limit for the statistic defined in |

`ucl` |
the upper confidence limit for the statistic defined in |

`nboot` |
the number of bootstrap samples; it is used only if |

`conf.level` |
the confidence level for calculating the |

`nrep` |
the resampling (with replacement) number for each sample size in |

`graph` |
logical; default is |

`...` |
further graphical arguments. |

### Details

If `ucl`

or `lcl`

is `NULL`

, `fun`

must be defined as in `boot`

, i.e.,
the first argument passed will always be the original data and the second will be a vector of indices,
frequencies or weights which define the bootstrap sample. By now, `samplesize`

considers the
second argument only as index.

### Value

A list of

`CI` |
a vector containing the lower and the upper confidence limit for the statistic evaluated. |

`pointsOut` |
a data frame containing the sample sizes (in |

### Side Effects

If `graph = TRUE`

, a graphic with the dispersion of the estimates for each sample size,
as well as the graphic containing the number of points outside the confidence interval for
the reference sample.

### Author(s)

Anderson Rodrigo da Silva <anderson.agro@hotmail.com>

### Examples

```
cv <- function(x, i) sd(x[i]) / mean(x[i]) # coefficient of variation
x = rnorm(20, 15, 2)
cv(x)
samplesize(x, cv)
par(mfrow = c(1, 3), cex = 0.7, las = 1)
samplesize(x, cv, lcl = 0.05, ucl = 0.20)
abline(h = 0.05 * 500, col = "blue") # sample sizes with 5% (or less) out CI
# End (not run)
```

*biotools*version 4.2 Index]