Generalized Linear Model with options to estimate logistic, probit, ordinal, multinomial and custum link function models. Provides options to estimate posthoc, simple effects and slopes, plots of main effects and interaction. Model comparison is also an option.

gamlj_glm(
  formula = NULL,
  data,
  model_type = "linear",
  dep = NULL,
  factors = NULL,
  covs = NULL,
  offset = NULL,
  model_terms = NULL,
  fixed_intercept = TRUE,
  nested_intercept = NULL,
  custom_family = "gaussian",
  custom_link = "identity",
  nested_terms = NULL,
  omnibus = "LRT",
  estimates_ci = FALSE,
  ci_method = "wald",
  boot_r = 1000,
  ci_width = 95,
  contrasts = NULL,
  show_contrastnames = TRUE,
  show_contrastcodes = FALSE,
  vcov = FALSE,
  plot_x = NULL,
  plot_z = NULL,
  plot_by = NULL,
  plot_raw = FALSE,
  plot_yscale = FALSE,
  plot_xoriginal = FALSE,
  plot_black = FALSE,
  plot_around = "ci",
  emmeans = NULL,
  posthoc = NULL,
  simple_x = NULL,
  simple_mods = NULL,
  simple_interactions = FALSE,
  covs_conditioning = "mean_sd",
  ccm_value = 1,
  ccp_value = 25,
  covs_scale_labels = "labels",
  adjust = list("bonf"),
  covs_scale = NULL,
  expb_ci = TRUE,
  es = list("expb"),
  propodds_test = FALSE,
  plot_scale = "response"
)

Arguments

formula

(optional) the formula of the model compatible with glm. If not passed, model terms should be defined as a list in model_terms option.

data

the data as a data.frame

model_type

define the type of model (link function and distribution combination) required. It can be linear, poisson, poiover, nb, logistic, probit, custom, ordinal, multinomial, and beta.

dep

a string naming the dependent variable from data; the variable must be numeric. Not needed if formula is used.

factors

a vector of strings naming the fixed factors from data. Not needed if formula is used.

covs

a vector of strings naming the covariates from data. Not needed if formula is used.

offset

a vector of strings naming the offset variables.

model_terms

a list of character vectors describing fixed effects terms. Not needed if formula is used.

fixed_intercept

TRUE (default) or FALSE, estimates fixed intercept. Not needed if formula is used.

nested_intercept

TRUE (default) or FALSE, estimates fixed intercept. Not needed if formula is used.

custom_family

Distribution family for the custom model, accepts gaussian, binomial, gamma and inverse_gaussian.

custom_link

Distribution family for the model_type="custom", accepts identity, log and inverse. Use onemu2 for 1/mu^2).

nested_terms

a list of character vectors describing effects terms for nested model. It can be passed as right-hand formula.

omnibus

Whether the omnibus test for the model should be wald or LRT.

estimates_ci

TRUE (default) or FALSE , coefficients CI in tables

ci_method

The method used to compute the confidence intervals. `wald` uses the Wald method to compute standard errors and confidence intervals. `profile` computes Profile Likelihood Based Confidence Interval, in which the bounds are chosen based on the percentiles of the chi-square distribution around the maximum likelihood estimate. `quantile` performs a non-parametric boostrap, with `boot_r` repetitions, and compute the CI based on the percentiles of the boostrap distribution. `bcai` implements the bias-corrected bootstrap method.

boot_r

a number bootstrap repetitions.

ci_width

a number between 50 and 99.9 (default: 95) specifying the confidence interval width for the plots.

contrasts

a named vector of the form c(var1="type", var2="type2") specifying the type of contrast to use, one of deviation, simple, dummy, difference, helmert, repeated or 'polynomial'. If NULL, simple is used. Can also be passed as a list of list of the form list(list(var="var1",type="type1")).

show_contrastnames

TRUE or FALSE (default), shows raw names of the contrasts variables in tables

show_contrastcodes

TRUE or FALSE (default), shows contrast coefficients tables

vcov

TRUE or FALSE (default), shows coefficients covariances

plot_x

a string naming the variable placed on the horizontal axis of the plot

plot_z

a string naming the variable represented as separate lines in the plot

plot_by

a list of variables defining the levels at which a separate plot should be produced.

plot_raw

TRUE or FALSE (default), plot raw data along the predicted values

plot_yscale

TRUE or FALSE (default), set the Y-axis range equal to the range of the observed values.

plot_xoriginal

TRUE or FALSE (default), use original scale for covariates.

plot_black

TRUE or FALSE (default), use different linetypes per levels.

plot_around

'none' (default), 'ci', or 'se'. Use no error bars, use confidence intervals, or use standard errors on the plots, respectively.

emmeans

a rhs formula with the terms specifying the marginal means to estimate (of the form '~x+x:z')

posthoc

a rhs formula with the terms specifying the table to apply the comparisons (of the form '~x+x:z'). The formula is not expanded, so x*z becomes x+z and not x+z+x:z. It can be passed also as a list of the form 'list("x","z",c("x","z")'

simple_x

The variable for which the simple effects (slopes) are computed

simple_mods

the variable that provides the levels at which the simple effects are computed

simple_interactions

should simple Interactions be computed

covs_conditioning

'mean_sd' (default), 'custom' , or 'percent'. Use to condition the covariates (if any)

ccm_value

how many st.deviations around the means used to condition simple effects and plots. Used if simpleScale='mean_sd'

ccp_value

offsett (number of percentiles) around the median used to condition simple effects and plots. Used if simpleScale='percent'

covs_scale_labels

how the levels of a continuous moderator should appear in tables and plots: labels, values and values_labels, ovalues, ovalues_labels. The latter two refer to the variable original levels, before scaling.

adjust

one or more of 'none', 'bonf','tukey' 'holm'; provide no, Bonferroni, Tukey and Holm Post Hoc corrections respectively.

covs_scale

a named vector of the form c(var1='type', var2='type2') specifying the transformation to apply to covariates, one of 'centered' to the mean, 'standardized','log' or 'none'. 'none' leaves the variable as it is.

expb_ci

TRUE (default) or FALSE , exp(B) CI in table

es

Effect size indices. expb (default) exponentiates the coefficients. For dichotomous dependent variables relative risk indices (RR) can be obtained. marginals computes the marginal effects.

propodds_test

Test parallel lines assumptions in cumulative link model (ordinal regression)

plot_scale

Chi-squared computation method. 'lrt' (default) gives LogLikelihood ration test, 'wald' gives the Wald Chi-squared.

Value

A results object containing:

results$modelThe underlying estimated model
results$infoa table
results$main$r2a table of R
results$main$fita table
results$main$anovaa table of ANOVA results
results$main$coefficientsa table
results$main$vcova table
results$main$contrastCodeTablesan array of contrast coefficients tables
results$main$marginalsa table
results$main$relativeriska table
results$main$paralleltesta table
results$posthocan array of post-hoc tables
results$simpleEffects$anovaa table of ANOVA for simple effects
results$simpleEffects$coefficientsa table
results$simpleInteractionsan array of simple interactions tables
results$emmeansan array of predicted means tables
results$mainPlotsan array of results plots
results$plotnotesa html
results$predictedan output
results$residualsan output

Tables can be converted to data frames with asDF or as.data.frame. For example:

results$info$asDF

as.data.frame(results$info)

Examples

   data <- emmeans::neuralgia
   GAMLj3::gamlj_glm(formula = Pain ~ Duration,
                    data = data,
                    model_type = "logistic"
                    )
#> 
#>  GENERALIZED LINEAR MODEL
#> 
#>  Model Info                                                                 
#>  ────────────────────────────────────────────────────────────────────────── 
#>    Info                                                                     
#>  ────────────────────────────────────────────────────────────────────────── 
#>    Model Type       Logistic Model    Model for binary y                    
#>    Model            stats::glm        Pain ~ 1 + Duration                   
#>    Distribution     Binomial          Dichotomous event distribution of y   
#>    Link function    Logit             Log of the odd of y                   
#>    Direction        P(y=1)/P(y=0)     P( Pain = Yes ) / P( Pain = No )      
#>    Sample size                  60                                          
#>    Converged        yes                                                     
#>    C.I. method      Wald                                                    
#>  ────────────────────────────────────────────────────────────────────────── 
#> 
#> 
#>  MODEL RESULTS
#> 
#>  Model Fit                                                    
#>  ──────────────────────────────────────────────────────────── 
#>    R²            Adj. R²        df    X²          p           
#>  ──────────────────────────────────────────────────────────── 
#>    0.01983700    0.007567546     1    1.616779    0.2035415   
#>  ──────────────────────────────────────────────────────────── 
#> 
#> 
#>  Additional indices                                            
#>  ───────────────────────────────────────────────────────────── 
#>    Info              Model Value    Comment                    
#>  ───────────────────────────────────────────────────────────── 
#>    LogLikelihood      -39.943206                               
#>    AIC                 83.886413    Less is better             
#>    BIC                 88.075102    Less is better             
#>    Deviance            79.886413    Less is better             
#>    Residual DF         58.000000                               
#>    Chi-squared/DF       1.028444    Overdispersion indicator   
#>  ───────────────────────────────────────────────────────────── 
#> 
#> 
#>  Omnibus tests                               
#>  ─────────────────────────────────────────── 
#>                X²          df    p           
#>  ─────────────────────────────────────────── 
#>    Duration    1.616779     1    0.2035415   
#>  ─────────────────────────────────────────── 
#> 
#> 
#>  Parameter Estimates (Coefficients)                                                                                          
#>  ─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── 
#>    Name           Effect         Estimate       SE            Exp(B)       Lower        Upper       z            p           
#>  ─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── 
#>    (Intercept)    (Intercept)    -0.34728878    0.26600165    0.7066012    0.4195207    1.190133    -1.305589    0.1916924   
#>    Duration       Duration       -0.02971640    0.02390160    0.9707208    0.9262949    1.017277    -1.243281    0.2137643   
#>  ─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── 
#>