As YLAN say, variance is a measure of deviation of results. Its not the fact, that a bad beat can happen. This also mean, that there is not one variance for cash games and another for tournaments, because many other factors are important. Starting with cash games variance will depend on the average pot size, how deep you buy in, and how many players are involved in each pot. In a loose and splashy live game, where people open to 7BB and get 5 callers, variance will be significantly larger than in a nitty online game, where people min-raise and only get called by big blind. And it will be even larger, if you are playing with a deep stack like 500BB instead of the online typical 100BB.
Your own playing style also matter for variance. If you tend to fold in marginal spots, that will reduce variance. An example could be facing a 5-bet jam with AKs. If its a late position confrontation, calling will often be close to neutral EV but will drive up variance significantly, because you either lose or win an entire stack instead of always losing the amount you 4-bet. Variance can be reduced though, if you and the opponent agree to run it multible times, or if the
poker site offer all-in insurance (for cash games).
Variance in tournaments also depend heavily on the payout structure. In heads-up SnGs or DoNs you will cash half the time, and the cashes are always the same. This mean, that variance is as low, as it can be for a tournament. At the other extreme we can take a satellite, which only reward tickets to the top 1% of players. Here an average player will only cash 1% of the time, and then he also need to cash in the target tournament to make any money. And for that reason swings will be enormous relative to the size of the buyin.
Variance is also large in traditional MTTs, especially those with large fields. This is because, even though something like 15-20% of the field cashes, a lot of the money goes to the top 3-5 places, and those are difficult to reach, if you compete with 1.000+ other players. And this is the main reason why, if you compare MTTs with cash games, then variance is definitely larger in MTTs. If on the other hand you play heads-up SnGs or DoNs, then variance is not that much larger than for cash games.
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and I noticed that some people were saying that the variance is the same in both (which makes sense to me) but others were suggesting that there was a difference in variance between cash games and tournaments.
