# Plot effect stars. Plots effect stars for grouped coefficients. Effect stars are applicable if the parameters of a model are grouped in some sense. For example, the parameters of a multinomial logit models are grouped by the covariates, i.e. per covariate there is one estimate per response category. But also in many other models, the parameters can have a fixed grouping structure. All estimates have to be positive, typically the exponentials of the estimates are plotted. Every effect star comes with a circle of radius 1. This circle represents the case of no effect, i.e. `exp(0)=1`. ```r ## Default S3 method: effectstars(x, names = NULL, subs = NULL, labels = NULL, control = star.ctrl(), cols = NULL, fixed = FALSE, scale = 1, ...) ``` ## Arguments - `x`: A matrix containing all coefficients to plot, one column per group/covariate, one row per category. If the arguments `names` and `labels` are not specified, the `colnames` and `rownames` of `x` are used. - `names`: A vector containing all group/covariate names, will be used as titles of single effect stars. If NULL, `colnames` of `x` is used. - `subs`: A vector containing all subtitles, one per group/covariate. - `labels`: A vector or a matrix containing labels of the categories. If labels is a matrix, it needs to have the same dimensions as `x`. Otherwise, `labels` is a vector with length equal to the number of categories, i.e. number rows of `x`. If NULL, `rownames` of `x` is used. - `control`: Control argument (to set graphical parameters) for method `effectstars`, see `star.ctrl`. - `cols`: Number of columns for arranging effect stars - `fixed`: If `TRUE`, all circles have the same radius. If `FALSE`, every star is scaled so that the length of the longest ray is equal for all stars. - `scale`: Global factor to increase (`scale`>1) or decrease (`scale`<1) the size of the stars. - `...`: possible further arguments ## Examples ```r ## Not run: ##################### ### Simple example for basic effectstars function p <- 4; k <- 5 coefs <- matrix(exp(rnorm(p*k,sd=0.5)),ncol=k) rownames(coefs) <- paste("Variable",1:p) colnames(coefs) <- paste("Cat",1:k) effectstars(coefs) ##################### ### Example for effect stars for a multivariate logit model data(xs.nz, package = "VGAMdata") xs.nz$age <- scale(xs.nz$age) library(VGAM) cats_dogs <- vglm(cbind(cat, dog) ~ age + sex + marital, data = xs.nz, family = binom2.or(zero = NULL)) summary(cats_dogs) ## quick and dirty effectstars(exp(coef(cats_dogs, matrix = TRUE))) ## make it pretty # create the effects matrix you want to plot, name rows and columns effects <- exp(coef(cats_dogs, matrix = TRUE)) colnames(effects) <- c("cat", "dog", "OR") rownames(effects) <- c("Intercept", "Age", "Gender", rep("Marital", 3)) # create subtitles containing category labels of predictors subs <- c(rep("",2), "(male)", "(married)", "(separated/divorced)", "(widowed)") # create labels containing the response categories and all p-values p_values <- formatC(summary(cats_dogs)@coef3[,4], format="f", digits=3) labels <- matrix(paste0(rep(c("cat", "dog", "OR"), nrow(effects)), "\n(", p_values, ")"), byrow = TRUE, ncol = 3) # plot effectstars effectstars(effects, labels = labels, subs = subs) ##################### ## Example for method effectstars.vglm for a multinomial logit model calculated in VGAM data(election) library(VGAM) m_elect <- vglm(Partychoice ~ Gender + West + Age + Union + Highschool + Unemployment + Pol.Interest + Democracy + Religion, family = multinomial(), data = election) effectstars(m_elect) ## End(Not run) ``` ## References Tutz, G. and Schauberger, G. (2013): **Visualization of Categorical Response Models - from Data Glyphs to Parameter Glyphs**, Journal of Computational and Graphical Statistics 22(1), 156--177. Gerhard Tutz (2012): **Regression for Categorical Data**, Cambridge University Press ## See Also `star.ctrl`, `effectstars.vglm`, `effectstars.DIFlasso`, `effectstars.DIFboost` ## Author(s) Gunther Schauberger gunther.schauberger@tum.de [https://www.sg.tum.de/epidemiologie/team/schauberger/](https://www.sg.tum.de/epidemiologie/team/schauberger/)

effectstars.default function