As with RTP, anyone frequenting discussion boards and blogs devoted to online casinos will have seen this term discussed by players and operators alike.
I’m not a mathematics professor, so if you want the complete technical description of variance and how it is calculated, then please visit the Wiki page at http://en.wikipedia.org/wiki/Variance
We will discuss Variance only as it applies to casino games, and in the simplest way possible.
So what’s it all about?
If you have read our previous article regarding RTP, you will have seen us discuss the idea of how much a slot pays back over the long term. In other words, WHAT it pays.
Variance is related to TRTP. It is an indication of what “kind” of play you can expect from a particular game, and relates to how a game achieves its TRTP. In other words, HOW it pays.
In our RTP article, we talked about how boring it would be to have a 95% TRTP slot that paid out exactly .95c for every $1 spin.
In this example, the payout of the slot does not VARY, so its Variance is ZERO (this is the only time we will actually talk about specific variance values as they are not relevant to this discussion and well beyond its scope). You get .95c every single time you spin $1.
Win Big…or Not
Variance is what makes games playable. It makes them exciting. It allows for huge wins, and consequently huge losses.
Every game has a Variance of some kind, and in casino terms, each game is placed into one of three Variance categories – High, Medium and Low.
Each of these categories gives you an idea of what kind of experience you are likely to have when you play those games. It gives you an idea of:
- How likely you are to hit a huge win
- How fast you are likely to lose your bankroll
- How you need to manage your bankroll
Notice the word “likely”. The categories, listed below, are only a guide, and do not mean something will or will not definitely occur. The general idea of each category is:
The more frequent combinations pay less, and the less frequent combinations pay more.
It basically means that there will be very big hits that will occur less often, and very small hits that will occur more often. It is not uncommon to go dozens of spins with no payout at all.
A more balanced paytable is employed. The very big hits can still happen, but they tend to be not quite as large as high variance slots.
You will also find the smaller combinations pay out better than high variance. MV slots can still eat your bankroll fast, but they tend to “throw you a bone” more often to keep you playing.
Perfect for players with a small bankroll who like to play for entertainment, and aren’t too concerned about whether they win a great amount.
The difference between the top paying symbols and the bottom ones is fairly small. Basically, you should expect frequent small-to-medium hits with the odd large win thrown in for good measure. It will not eat your bankroll as quickly as the other two types.
How to Tell?
Well, some casinos provide this information alongside their games, and sometimes in the help files. You can certainly use this as a guide, but the problem is that there is no accepted standard for categorization of games.
What might be described by one casino as high variance might actually be considered medium variance by another.
The differences are usually only one category i.e. it is most unlikely that a high variance slot would be described as low variance by a different operator.
However, by and large the best way, in our opinion, is to visit some reputable gambling forums and search for your favorite games.
If you cannot find anything, post a question and you will get some feedback from people who have actually played the games and can give you a good idea of their variance.
Variance is also important when considering bonuses and how to play them. We discuss this on the (LINK) BONUSES (LINK) page.
So, in summary, the TRTP tells you WHAT the game pays back, and the Variance tells you HOW it pays it back.