# caracal

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 Dec9 awarded Nice Question Nov14 awarded Enlightened Nov14 awarded Nice Answer Nov8 awarded Yearling Oct14 awarded Pundit Jul24 comment How to predict rank in ordinal regression using R? predict(fit, data.frame(QD=78), type="fitted.ind") gives predicted class probabilities, what you got is the value of the linear predictor, see this answer. Jul3 comment Getting p-values for “multinorm” in R (nnet package) You can use model comparisons with likelihood ratio tests for a full and reduced model using nnet's anova() function. Jun15 comment Can bootstrap be used to replace non-parametric tests? @GaëlLaurans For an example of generating the exact (permutation) distribution of the Wilcoxon rank-sum test statistic (equivalent to Mann-Whitney) and of the Kruskal-Wallis test statistic, see this answer. Jun10 comment Why do Minitab and SPSS give opposite results in Ordinal Logistic Regression? See this answer for an explanation of the possible ways to write down the same model for ordinal logistic regression. Jun10 comment Getting the bootstrap-validated AUC in R Frank Harrell's rms package has functions for this task. Fit the model with fit <- lrm(outcomes ~ X1 + X2 + X3, data=my.data, x=TRUE, y=TRUE), then use bootstrap validation with validate(fit, B=1000). The output matrix includes the optimism corrected values, but only shows Somers' $D_{xy}$. However $\text{AUC} = 0.5 \cdot D_{xy} + 0.5$. May23 comment Dummy variables in multiple regression, why use an intercept? As @Glen_b pointed out, things get more complicated with multiple factors. E.g., in an unbalanced two-factorial ANOVA, SS type III model comparisons depend on the coding scheme - it has to be a sum-to-zero scheme like Helmert or effect coding. May8 comment R, Differences between lm and aov @GaëlLaurans Ok. May8 answered R, Differences between lm and aov May8 answered Repeated-measures error in R ezANOVA using more levels than subjects (balanced design) Apr29 awarded Nice Answer Apr28 answered R p-value half to SPSS rANOVA Apr25 comment Confidence Bands in non linear mixed effects models Did you have a look at the suggestion laid on in the r-sig-mixed-models FAQ draft? Mar28 comment Different odds ratios from formula and R's fisher.test From the help page for fisher.test(): "Note that the conditional Maximum Likelihood Estimate (MLE) rather than the unconditional MLE (the sample odds ratio) is used." Mar18 awarded Good Answer Mar3 comment How can I test the likelihood that two Poisson data sets are drawn from the same distribution in R? This test is done using the poisson.test() function in R.