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# ggConfidenceCurve: Confidence Curves

## Description

Confidence curves are a way to show the confidence in an estimate computed from sample data. They are useful because they show all confidence levels simultaneously, thereby giving a good sense of the accuracy of the estimate, without forcing the researchers to make a more or less arbitrary choice for one confidence level.

## Usage

```ggConfidenceCurve(metric = "d",
value = NULL,
n = NULL,
conf.level = NULL,
wRange = c(0.05, 0.8),
curveSize = 1,
curveColor = "black",
confRange = c(1e-04, 0.9999),
confLines = c(0.5, 0.8, 0.95, 0.99),
widthLines = c(min(wRange), 0.1, 0.2, 0.3, max(wRange)),
lineColor = brewer.pal(9, 'Set1'),
lineSize = 1,
lineAlpha = .5,
xlab = metric,
steps = 1000,
theme = theme_bw(),
outputFile = NULL,
outputWidth = 16,
outputHeight = 16,
ggsaveParams = list(units='cm',
dpi=300,
type="cairo"))```

## Arguments

metric

The metric, currently only 'd' (Cohen's d) and 'r' (Pearson's r) are implemented.

value

The value for which to create the confidence curve plot.

n

The sample size for which to create the confidence curve plot. If `n` is specified, the y axis shows confidence levels (i.e. a conventional confidence curve is generated). If `n` is set to `NULL`, the y axis shows sample sizes. Either `n` or `conf.level` must be `NULL`.

conf.level

The confidence level for which to create the confidence curve plot. If `conf.level` is specified, the y axis shows sample sizes. If `conf.level` is set to `NULL`, the y axis shows confidence levels (i.e. a conventional confidence curve is generated). Either `n` or `conf.level` must be `NULL`.

wRange

The range of 'half-widths', or margins of error, to plot in the confidence curve plot if no sample size is specified (if `n=NULL`).

curveSize

The line size of the confidence curve line.

curveColor

The color of the confidence curve line.

confRange

The range of confidence levels to plot.

confLines, widthLines

If a traditional confidence curve is generated, lines can be added to indicate the metric values corresponding to the lower and upper confidence interval bounds. For an inverse confidence curve, lines can be added to inficate the metric values and sample sizes corresponding to specific margins of error (or 'half-widths').

lineColor

If confidence or 'interval width lines' lines are added (see `confLines`), this is the color in which they are drawn. Specify a vector (e.g. `brewer.pal(9, 'Set1')`) to have the colors drawn in different colors for each confidence level or width.

lineSize

If confidence lines or 'interval width lines' are added (see `confLines` and `widthLines`), these arguments specify the color and size in which they are drawn.

lineAlpha

The alpha value (transparency) of the confidence lines or 'interval width lines'.

xlab

The label on the x axis.

steps

The number of steps to use when generating the data for the confidence curves' more steps yield prettier, smoother curves, but take more time.

theme

The `ggplot` theme to use.

Whether to use a gradient as background to make the confidence more explicit. This is experimental and pretty influential in terms of how the plot looks. The default gradient, used when passing `TRUE`, uses black as background color when the confidence is 0 percent, and white for 100 percent. If two colors are specified, these are used instead.

If using a gradient, the width of the `geom_tile` geoms used to create the gradient.

outputFile

A file to which to save the plot.

outputWidth, outputHeight

Width and height of saved plot (specified in centimeters by default, see `ggsaveParams`).

ggsaveParams

Parameters to pass to ggsave when saving the plot.

## Value

A `ggplot2` plot.

## References

Bender, R., Berg, G., & Zeeb, H. (2005). Tutorial: Using confidence curves in medical research. Biometrical Journal, 47(2), 237-247. http://doi.org/10.1002/bimj.200410104

Birnbaum, A. (1961). Confidence curves: An omnibus technique for estimation and testing statistical hypotheses. Journal of the American Statistical Association, 56(294), 246-249. http://doi.org/10.1080/01621459.1961.10482107

`cohensdCI`, `pwr.cohensdCI`, `confIntR`, `pwr.confIntR`
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