# curve.density: Draw density plots In FlexReg: Regression Models for Bounded Continuous and Discrete Responses

 curve.density R Documentation

## Draw density plots

### Description

The function draws a curve corresponding to the probability density/mass function of the specified distribution (beta, flexible beta, variance-inflated beta, binomial, beta-binomial, or flexible beta-binomial). For beta, flexible beta, and variance-inflated beta, it also allows to include the representation of the probability of augmentation in zero and/or one values.

### Usage

``````curve.density(
type = NULL,
size = NULL,
mu = NULL,
theta = NULL,
phi = NULL,
p = NULL,
w = NULL,
k = NULL,
q0 = NULL,
q1 = NULL,
...
)
``````

### Arguments

 `type` a character specifying the distribution type to be plotted (`"Beta"`, `"FB"`, `"VIB"`, `"Bin"`, `"BetaBin"`, or `"FBB"`). `size` the total number of trials (to be specified only if `type` is `"Bin"`, `"BetaBin"`, or `"FBB"`). `mu` the mean parameter of the distribution. It must lie in (0, 1). `theta` the overdispersion parameter (to be specified only if `type` is `"BetaBin"` or `"FBB"`). It must lie in (0, 1). `phi` the precision parameter (if `type` is `"BetaBin"` or `"FBB"`, it represents an alternative way to specify the `theta` parameter). It must be a real positive value. `p` the mixing weight (to be specified only if `type` is `"FB"`, `"VIB"`, or `"FBB"`). It must lie in (0, 1). `w` the normalized distance among component means of the FB and FBB distributions (to be specified only if `type = "FB"`, or `type = "FBB"`). It must lie in (0, 1). `k` the extent of the variance inflation (to be specified only if `type = "VIB"`). It must lie in (0, 1). `q0` the probability of augmentation in zero (to be specified only if `type` is `"Beta"`, `"FB"`, or `"VIB"`). It must lie in (0, 1). In case of no augmentation, it is `NULL` (default). `q1` the probability of augmentation in one (to be specified only if `type` is `"Beta"`, `"FB"`, or `"VIB"`). It must lie in (0, 1). In case of no augmentation, it is `NULL` (default). `...` additional arguments of `stat_function`.

### References

Ascari, R., Migliorati, S. (2021). A new regression model for overdispersed binomial data accounting for outliers and an excess of zeros. Statistics in Medicine, 40(17), 3895–3914. doi:10.1002/sim.9005

Di Brisco, A. M., Migliorati, S. (2020). A new mixed-effects mixture model for constrained longitudinal data. Statistics in Medicine, 39(2), 129–145. doi:10.1002/sim.8406

Di Brisco, A. M., Migliorati, S., Ongaro, A. (2020). Robustness against outliers: A new variance inflated regression model for proportions. Statistical Modelling, 20(3), 274–309. doi:10.1177/1471082X18821213

Ferrari, S.L.P., and Cribari-Neto, F. (2004). Beta Regression for Modeling Rates and Proportions. Journal of Applied Statistics, 31(7), 799–815. doi:10.1080/0266476042000214501

Migliorati, S., Di Brisco, A. M., Ongaro, A. (2018). A New Regression Model for Bounded Responses. Bayesian Analysis, 13(3), 845–872. doi:10.1214/17-BA1079

### Examples

``````curve.density("Beta", mu=.5, phi=20)
curve.density("Beta", mu=.5, phi=20, q1 = .3)
curve.density("FB", mu=.5, phi=20, p=.4, w=.8)
curve.density("FB", mu=.5, phi=20, p=.4, w=.8, q0= .1)
curve.density("VIB", mu=.5, phi=20, p=.9, k=.8, col=3)
curve.density("VIB", mu=.5, phi=20, p=.9, k=.8, col=3, q0=.1, q1=.3)

curve.density("Bin", size=10, mu=.7)
curve.density("BetaBin", size=10, mu=.7, phi=10)
curve.density("FBB", size=10, mu=.7, phi=10, p=.2,w=.7)

``````

FlexReg documentation built on Sept. 29, 2023, 9:06 a.m.