The Algorithm

So just what the hell is going on? How does this all work?


Predictions were the first thing we started doing here at Rugby4Cast, way back in the mists of time, and it has remained steadfastly the most controversial topic throughout. Regardless of accuracy there are always a few trolls out there sharpening the knives.

So how is it done? Is it all just done by watching a couple of goldfish swimming around a bowl? Sometimes it feels like that that might be better…

What started out as just a simple Excel spreadsheet that used average scores home and away and made some slight adjustments based on team rankings has now evolved into a full machine learning algorithm written in Python. Talk about using a sledgehammer to crack a walnut.

Previous results are scraped from various sources and thrown into the Algorithm every week (usually Monday if you want specifics). The Algorithm churns through this mish-mash of matches and players, updating our databases, calculating rankings for teams and sorting out a few other metrics which we use at various stages of the process.

The Algorithm uses these metrics from historical matches to work out its expected score for each match and the probabilities of each outcome using various regression tools.

Here’s one we made earlier

More accurately speaking, this means that each predicted score can be thoughts of as a metric to describe the relative historical strength of the two teams, based on their performances over previous years. However, we think it is more fun to think of them as predictions. At the very least, it certainly serves to provoke those trolls lurking on Twitter (you know who you are – yes you!)

Currently, matches are predicted for the next 60 or so days in the Gallagher Premiership, Pro 14, Top 14, European Cups, Super Rugby and International matches. We could go further, but beyond that the predictions become steadily less accurate as the expected scores will change based on the results in between. But we’re working on it, don’t worry.

We are also looking to roll out similar predictions and stats for the various Southern Hemisphere Cups, along with Major League Rugby and the Japanese Top League in due course. Women’s rugby is also very definitely on the list, as soon as we can find an easily scrape-able resource for matches. If you have any ideas for sources, please point them out.

These predictions are uploaded into the website every Monday (give or take) so you have a full 5 or 6 days to check them out and get really riled up regarding how incorrect and biased you think they are. Please be sure to let us know just how angry you get on all the various social media platforms.

If you’d like you can also subscribe to our mailing list where you will get all the latest updates straight to your inbox, so you don’t need to worry about all the middlemen. Lovely job.

The results relative to the previous predictions are also uploaded weekly so you can see how the Algorithm has performed over time. A running total for how it is performing in each league is also shown in the interests of full disclosure. We aren’t hiding anything! Apart from the bodies of those of have bested us. Those are very well hidden.


This is always the first thing people ask about after hearing about the predictions.

Yes, we do bet based on these predictions. And yes, it does beat the bookies. Bonzer. Feel free to join in. See our advice for using the predictions for betting here.


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What this also means is that we collect a huge amount of data. At the time of writing we have over 21,000 rugby matches in our database, and well over 700,000 players associated with those matches.

This is where all the information that we post on various social media platforms and articles comes from. Generally, it is all cross-referenced and checked against the other data sources to ensure that it is correct but it is entirely possible that something has slipped through the net, so if you see anything, please give us a shout to point it out. There’s only so much we can do.

If you have any questions about the data, the model or anything else, please don’t hesitate to get in contact. There’s nothing we’d like better than a good argument about the importance of home advantage in the outcome of a rugby match!

Confused? Us, too!

But you can always contact us with questions.

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