Variance is a description of how far numbers in a set are from their average. There is a lot of variance in poker. Your expected earnings, the amount of money you can expect to make in a time period, can vary wildly from the amount you do make, especially in the short run. In general, this is a good thing, as it allows amateur players to win frequently, making it more fun for them, and giving them the illusion of having skill. It can be difficult for winning players to deal with losing several days in a row or even 8 out of 10. Since I have switched to playing poker in person, I play many fewer hands (about 30 an hour instead of 1000 or more on the internet) and losing streaks that would be over in an hour on the internet(1000 hands) can stretch on for a week(1000 hands) when playing in person.
In practical terms, the more consistent your results are day after day, the less variance you have. Let me give you a real world example of how variance affects people. My Mom is a teacher and has an average drive of 20 minutes to the school where she works. She has to be there on time or she gets written up. What time should she leave the house to get there on time?
Well, the answer lies in variance. Does it take her exactly 20 minutes a day because there is never traffic? Does it take her 5 minutes 4 days a week and an hour 1 day a week? How are her driving times distributed? You don’t have to be a mathematician or use formulas and graphs to figure out what time she should leave for work. My mom knows that there is a drawbridge that occasionally opens on her way to work(maybe once a week) and that costs her approximately 5 minutes when it opens. Other than that there is no traffic, so she should leave at 7:35 to ensure that she gets there by 8:00, which is exactly what she does. Well done Mom! Note that the variance in times causes her to leave the house 5 minutes a day earlier than she needs to 4 of the 5 days a week and thus “costs” her 5 minutes a day less at home.
What is the cost of variance to poker players? Aside from obscuring results and making it more difficult to determine who the winners and losers are, it is mental energy. Most poker players spend a lot of time worrying about their short term results and waste the energy they could be spending improving their poker game. In addition, frustrations such as “I never win” or “I missed all my flush draws today” can affect the way you play and can make you play hands less than optimally then if you were evaluating them at a different time.