I am trying to replicate a example that I found on Tom Mitchell's Machine Learning book using R. It is a example from chapter 6. There are 14 training examples (shown bellow) of the target concept PlayTennis, where each day is described by the attributes Outlook, Temperature, Humidity, and Windy. Training examples Outlook,Temperature,Humidity,Windy,Play overcast,cool,normal,true,yes overcast,hot,high,false,yes overcast,hot,normal,false,yes overcast,mild,high,true,yes rainy,cool,normal,false,yes rainy,mild,high,false,yes rainy,mild,normal,false,yes sunny,cool,normal,false,yes sunny,mild,normal,true,yes rainy,cool,normal,true,no rainy,mild,high,true,no sunny,hot,high,false,no sunny,hot,high,true,no sunny,mild,high,false,no Here's my code <!-- language: R --> library("klaR") library("caret") data = read.csv("example.csv") x = data[,-5] y = data$Play model = train(x,y,'nb',trControl=trainControl(method='cv',number=10)) Outlook <- "sunny" Temperature <- "cool" Humidity <- "high" Windy <- "true" instance <- data.frame(Outlook,Temperature,Humidity,Windy) predict(model$finalModel,instance) The example tries to predict the outcome for Outlook=sunny, Temperature=cool,Humidity=high and Wind=strong The problem is that I am getting a different prediction from the one in the book. Here's the probabilities I've got from my code no yes 0.001078835 0.9989212 Here's the book's probabilities no yes 0.0206 0.0053 My code classifies the unseen data as Yes and the book's classifier classifies it as No. Shouldn't both give the same answer since we are using the same naive bayes classifier?