# Questions tagged [gamlss]

Generalized additive models for location, scale and shape (GAMLSS).

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### How to improve the fit of a beta zero-inflated regression model (GAMLSS)?

I'm working with a response variable with values between 0.0 and 1.0. I have a lot of zero. Thus, I'm using beta zero-inflated regression model. Specifically, I'm using the function gamlss from the ...
9 views

### Catgeorical variable coefficients interpretation

if I have the following regression model in gamlss (or if it's a general concept) Y ~ var1 Where Y ~ beta, and var1=(g1,g2,g3) g1 is the reference level, what does it mean that the intercept is ...
483 views

### Betabinomial (BB) regression in the gamlss package (R)

I'd be grateful for any help with beta-binomial (BB) regression in the gamlss package: predictions from the fitted model of "mu" values for each observation in my data seem reasonable. But ...
32 views

### Standard errors in GAMLSS vs LMER

Why do the standard errors for gamlss are much lower than the standard errors from lmer? ...
556 views

### Beta regression fitted values

I have a beta regression model in R, have generated predicted (fitted) values based on my data, and plotted lines of those fitted values on a scatter plot of the actual data. I'm most used to GLMMs, ...
1 vote
59 views

### How to find the appropriate model to apply (GAMLSS)/Approving statistical thinking

I need to compute percentile curves using the LMS method (from the GAMLSS package/models) with Age and Height as predictors. What is the best way to determine which equation (with which transformation ...
1 vote
54 views

### Choosing whether to eliminate or keep a predictor in a GAMLSS model

I need to calculate the centile curve for y using a GAMLSS model with age and height as predictors. The plots below depict the relationship between log(y) and each of the independent variables. I ...
231 views

### Error in post-hoc analysis on gamlss model with emmeans: "Error in V[idx, idx, drop = FALSE] : subscript out of bounds" [closed]

I am utilizing gamlss currently because of its flexibility in specifying 'rarer' data families but run into an error when trying to compare 2-by-2 differences in mu effects for my fixed model factors. ...
52 views

### qBCCGo function in GAMLSS package (quantile function)

I am working with GAMLSS technique and I use LMS (with three parameters of mean,variation and skewness) method. I found the follwoing formula to calculate the lower limit of normal as the link ...
24 views

### Censoring in GAMLSS

I have some observations $y$ which have only few negative values $y_i\in (-\infty,0)$ and mostly non-negativ values, i.e. $y_i\in [0,\infty)$. I would like to estimate a censored logistic ...
38 views

### Need some help to identify the appropriate distribution

The residual plots of the following models are not normal, while the distribution of residuals between (-3 to 3) is normal in model m17. The worm plot of all equations appears to be correct. The goal ...
65 views

### Find the more appropriate fit by using term.plot in GAMLSS

I'm comparing several GAMLSS models and was wondering how I might use the term.plot to identify the best model/fit. What type of information can we get from this graph? Can I argue that the model with ...
1 vote
50 views

### A question about applying GAMLSS models

I want to make the growth chart by using age and height as predictors. As the scatter plots show a nonlinear relationship between age and y, I need to use the P-spline to make the statistical equation....
138 views

### How to compare centiles from different models?

I am comparing the centiles from different GAMLSS models. Which model has a better performance. Why? For model 1, the number of cases below 0.4 centile is 0.5. Is this possible? The number of cases ...
49 views

### Proportion/Ratio response variable

I need some advice to understand the following code. We are working with lung data and usually we use LMS technique to calculate the reference curves. In order to calcualte the curves with LMS method ...
1 vote
204 views

### Robust options to fit GLM or GAM for overdispersed Poisson counts (quasipoisson or negative binomial) in R

It appears glmrob from the robustbase library does not support quasipoisson or ...
482 views

1 vote
62 views

### ZINB boosting model (gamboostLSS) seems off in R, what could be the reason?

I have a dataset containing counts (values from 0 to 30) and different covariates. This is what the distribution of the count data looks like: After fitting a gamlss boosting model in R (with the ...
229 views

### Weibull distributed GLM with GAMLSS good fit?

I have data from a plant disease screen in a greenhouse. 145 plants in a greenhouse were inoculated with bacteria over the course of three days, and the amount of bacteria in the plant assessed at a ...
74 views

### How to interpret a n-related change in coverage for model (simulation study)

I have repeated measures data from n_subjects where each has n_obs number of measurements before and after some intervention, ...
290 views

### Johnson SU distribution parameters values from R/rugarch

I have fit a GARCH model where I set the distribution to the Johnson's SU. I don't fully understand the distribution parameters returned by the model. To begin with, from Wikipedia, Johnson's SU is ...
1 vote
116 views

### meanBEINF vs predict(model, type = "response') in BEINF GAMLSS. and determining odds of predictor variable coefficient

A variation of this question has been asked, but certain items remain unanswered - I am modeling the proportion of mortality (Prop) using a single continuous predictor variable which is temperature (...
1 vote
70 views

### Residual autocorrelation in non-stationary (gaulss) model

I'm fitting a non-stationary model using mgcv (family: gaulss()) where the data have been collected at different points in space....
2k views

### What is Mu in zero/one beta inflated models? (gamlss (BEINF))

I am estimating a zero/one inflated beta regression model with gamlss (family BEINF). My dependent variable is [0,1] with a lot of 0s, quite some 1s, and some values in between. This means I assume ...
1 vote
51 views

### Propensity Score Weighting in GAMLSS

in a project of mine i want to use a propensity score weighted gamlss model. However, the gamlss user guide states "In general using weights that are not frequencies is not recommended unless the ...
197 views

### How to transform an uniform distribution into a generalized beta 2 distribution using gamlss, fitdist or other?

Not comfortable with math and just R beginner, I get stuck on the following problem: Imagine that, for a variable ya (n=3000), the gamslss ...
146 views

### How to correctly specify and diagnose one-inflated beta regression mixed-models (using GAMLSS)

I would like to find out what variables influence/explain an efficiency score for an invasive species control method. As the score is defined on (0,1] and as some observations were not independent, I ...
1 vote
479 views

### R gamlss - fitting and simulating lognormal response

I believe I am making a mistake in parametrization in this case. My goal is fit a lognormal model to data using gamlss in R, then simulate from that fitted model. ...
396 views

### What distribution has exactly three parameters for mean, variance, and skewness?

Common distributions usually fix their skewness. Beta distribution has two parameters to determine all of the mean, variance, and skewness. Student-T's skewness can change by some definitions but it ...
156 views

### Regression with variance as outcome

Are there regression models where variance is the outcome, not mean? For instance, for interquartile range I may use quantile regression. But is there something similar for variance? For example, let ...
524 views

### GAMLSS Random Effect Coefficients

How do I extract the coefficients of my random effects in a Gamlss model? Let's take a simple example of a sample of individuals with intercepts which are normally distributed. Additional normally ...
92 views

### Does this graph support an assumption of homoscedasticity?

Does this graphics support the assumption of homoscedasticity?
309 views

### Is smoothing an appropriate solution to deal with model diagnostics in a GAMLSS?

I have just recently started using GAMLSS models (after being pointed in that direction in this question), and I'm wondering wether it's 'legit' to use smoothing (i.e. cubic splines in my case) to ...
1k views

### Post hoc analysis for gamlss model in R

I used a gamlss model for my data and would like to do some post hoc analysis afterwards. I tried the packages emmeans and ggemmeans but both of them give me an error: "Error in match.arg(type) : ...
1 vote
875 views

### How to model heteroscedasticity and get the coefficients?

I would like to model heteroscedasticity or better, the standard deviation of the mean as a function of x and retrieve the coefficients that says something about how standard deviation behaves with ...