# Inspect FBD parameter distributions visually

`FBD_normality_plot.Rd`

Produces plots of the distributions of fossilized birth–death process (FBD) parameters to facilitate the assessment of the assumptions of normality within time bins and homogeneity of variance across time bins.

## Arguments

- posterior
A data frame of posterior parameter estimates containing a single "Time_bin" column and one column for each FBD parameter value. Such data frame can be imported using

`combine_log`

followed by`FBD_reshape`

.

## Details

The plots produced include density plots for each parameter within each time bin (residualized to have a mean of zero), scaled so that the top of the density is at a value of one (in *black*). Superimposed onto these densitys are the densities of a normal distribution with the same mean and variance (and scaled by the same amount) (in *red*). Deviations between the normal density in *red* and the density of the parameters in *black* indiciate deviations from normality. The standard deviation of each parameter is also displayed for each time bin to facilitate assessing homogenity of variance.

## See also

`vignette("fbd-params")`

for the use of this function as part of an analysis pipeline.

`combine_log`

for producing a single data set of parameter posterior samples from individual parameter log files.

`FBD_reshape`

for converting posterior parameter table from wide to long format.

`FBD_tests1`

for statistical tests of normality and homogeneity of variance.

`FBD_tests2`

for tests of differences in parameter means.

## Examples

```
# See vignette("fbd-params") for how to use this
# function as part of an analysis pipeline
data("posterior3p")
posterior3p_long <- FBD_reshape(posterior3p)
FBD_normality_plot(posterior3p_long)
```