Conditional Probability Analysis: Quantifying the Proteas' Chance in the WTC Final

I applied conditional probability and weighted factors: recent form, head-to-head records, and venue bias: to estimate the Proteas' actual chance of beating Australia in the ICC World Test Championship Final.

Australia were clear favorites going into the ICC World Test Championship Final, but what were the actual chances of the Proteas walking away with the mace? I am Johannes, 18, and I am working toward a career in Quantitative Finance. To stay accountable (and share some cool insights), I am documenting my learning journey every day.

Today is Day 1, and I decided to jump into the core of Quantitative Finance: probability and statistics. The most straightforward way to determine the probability is through a concept called Conditional Probability. It sounds intense, but it is actually a useful and fairly quick way to figure out the likelihood of an event, given that several conditions or factors are in play.

Formally, that is written as: $P(\text{Proteas Win}) = P(\text{SA Win} | \text{Factor 1}, \text{Factor 2}, \dots, \text{Factor } n)$

To start, I used the overall probability of the Proteas beating Australia in Test matches, without digging too deeply into recent form. This serves as a good baseline. The number I found was 26.47%, the exact percentage of matches South Africa have won against Australia in Test format. I would have usually assumed 25%, but when it comes to exact probabilities, assumptions do not take you very far. I will show why in a moment.

Next, I looked at South Africa’s recent form in Test cricket. The most logical percentage to use here is their win rate during the World Test Championship: 69.44%. But that includes draws, which adds more complexity than I am ready to deal with yet. So I used their record without the draw: 8 wins from 11 games, giving a cleaner 72.7%.