# ci_sd: Confidence Interval for the Population Standard Deviation In confintr: Confidence Intervals

 ci_sd R Documentation

## Confidence Interval for the Population Standard Deviation

### Description

This function calculates confidence intervals for the population standard deviation. They are derived by calculating confidence intervals for the variance and then taking the square-root. For details, see `ci_var`.

### Usage

```ci_sd(
x,
probs = c(0.025, 0.975),
type = c("chi-squared", "bootstrap"),
boot_type = c("bca", "perc", "stud", "norm", "basic"),
R = 9999,
seed = NULL,
...
)
```

### Arguments

 `x` A numeric vector. `probs` Error probabilites. The default c(0.025, 0.975) gives a symmetric 95% confidence interval. `type` Type of confidence interval. One of "chi-squared" (default) or "bootstrap". `boot_type` Type of bootstrap confidence interval ("bca", "perc", "stud", "norm", "basic"). Only used for `type = "bootstrap"`. `R` The number of bootstrap resamples. Only used for `type = "bootstrap"`. `seed` An integer random seed. Only used for `type = "bootstrap"`. `...` Further arguments passed to `boot::boot`.

### Value

A list with class `cint` containing these components:

• `parameter`: The parameter in question.

• `interval`: The confidence interval for the parameter.

• `estimate`: The estimate for the parameter.

• `probs`: A vector of error probabilities.

• `type`: The type of the interval.

• `info`: An additional description text for the interval.

`ci_var`.

### Examples

```x <- 1:100
sd(x)
ci_sd(x)
sqrt(ci_var(x)\$interval)
ci_sd(x, type = "bootstrap", R = 999)
```

confintr documentation built on Sept. 29, 2022, 5:13 p.m.