Conditional probability: Its place in the mathematics curriculum

The late introduction of conditional probability in the curriculum statements is probably related to the automatic association of conditional probability with Bayes's theorem and the complicated analyses involving Venn diagrams or tree diagrams to work out the inverse probabilities in conditional problems. No doubt Bayes's theorem is a complex topic that is likely to be mastered by most students only at the senior secondary level. However, several other more straightforward uses can be made of conditional probability earlier in the curriculum. The examples that follow illustrate how conditional statement can be used to introduce conditional probabilities, how early applications can be found in sporting data, how independence can be introduced naturally, and how conditional probability can be related to data collection and presentation in two-way tables. These four topics can be introduced in grades 8 through 10.