# Standard deviation / Variance in VPW

Discuss video poker programs for the home user
Mr.Dawes
Senior Member
Posts: 143
Joined: Wed Apr 15, 2015 12:05 am

### Standard deviation / Variance in VPW

On VPW's bankroll calculator it shows two numbers for standard deviation and variance. For 9/6 JoB the variance is shown as 19.51 and 487.87 and the standard deviation is shown as 4.42 and 22.09 ( i rounded off). For both of these I am already familiar with the first numbers. Does anyone know what the second, higher numbers represent and what the implications of these numbers are?Thanks for any feedback.

New2vp
Video Poker Master
Posts: 1706
Joined: Mon Sep 11, 2006 4:02 am
The units for the first listed numbers are the number of bets (for standard deviation) and "bets squared" for variance.  The second number is the number of coins and coins squared and assumes a 5-coin bet.You might have noticed that the ratio within rounding is exactly 5 (for standard deviation) and exactly 25 (for variance).Equivalently, some might call the first numbers the "per coin" standard deviation and variance.

Mr.Dawes
Senior Member
Posts: 143
Joined: Wed Apr 15, 2015 12:05 am
Thanks new2vp. That makes sense, and I think those numbers give me a more realistic understanding of the variance of different games.

New2vp
Video Poker Master
Posts: 1706
Joined: Mon Sep 11, 2006 4:02 am
Yep, e.g., when comparing a game that has a larger than 5-coin max play with one that is 5 coins, the smaller first numbers do not tell the whole story.  E.g., comparing 9-6 Jacks or Better with 9-6 Quick Quads Jacks or Better, one can see that the the first has a 4.418 standard deviation while the QQs version is 4.667, indicating a measure of volatility that is only 6% higher.  However, when multiplying by the number of coins in the max bet, we see the comparison is actually 22.088 to 28.001, a difference of 27%.  This shows the higher relative "swingyness" of QQs a bit better.