# Compares the AIC of several outputs This function is used to compare the AIC of several outputs obtained with the same data but with different set of parameters. The parameters must be lists with $aic or $AIC or $value and $par elements or if AIC(element) is defined. if `$value` and `$par` are present in the object, the AIC is calculated as `2*factor.value*value+2*length(par)`. If `$value` is -log(likeihood), then factor.value must be 1 and if `$value` is log(likeihood), then factor.value must be -1. If several objects are within the same list, their AIC are summed. For example, compare_AIC(g1=list(group), g2=list(separe1, separe2)) can be used to compare a single model onto two different sets of data against each set of data fited with its own set of parameters. Take a look at `ICtab` in package `bbmle` which is similar. ```r compare_AIC( ..., factor.value = 1, silent = FALSE, FUN = function(x) specify_decimal(x, decimals = 2) ) ``` ## Arguments - `...`: Successive results to be compared as lists. - `factor.value`: The $value of the list object is multiplied by factor.value to calculate AIC. - `silent`: If TRUE, nothing is displayed. - `FUN`: Function used to show values ## Returns A list with DeltaAIC and Akaike weight for the models. ## Details compare_AIC compares the AIC of several outputs obtained with the same data. ## Examples ```r ## Not run: library("HelpersMG") # Here two different models are fitted x <- 1:30 y <- rnorm(30, 10, 2)+log(x) plot(x, y) d <- data.frame(x=x, y=y) m1 <- lm(y ~ x, data=d) m2 <- lm(y ~ log(x), data=d) compare_AIC(linear=m1, log=m2) # Here test if two datasets can be modeled with a single model x2 <- 1:30 y2 <- rnorm(30, 15, 2)+log(x2) plot(x, y, ylim=c(5, 25)) plot_add(x2, y2, col="red") d2 <- data.frame(x=x2, y=y2) m1_2 <- lm(y ~ x, data=d2) x_grouped <- c(x, x2) y_grouped <- c(y, y2) d_grouped <- data.frame(x=x_grouped, y=y_grouped) m1_grouped <- lm(y ~ x, data=d_grouped) compare_AIC(separate=list(m1, m1_2), grouped=m1_grouped) ## End(Not run) ``` ## See Also Other AIC: `ExtractAIC.glm()`, `FormatCompareAIC()`, `compare_AICc()`, `compare_BIC()` ## Author(s) Marc Girondot marc.girondot@gmail.com

compare_AIC function