Originally Posted by pokerman27
OK, so if those two data sets were poker session results in dollars for two different players although they've both made the same amount of money player 1 is the 'steadier' player with a lower standard deviation - am I right in saying then that the standard deviation for those two players would be 2.23 ($2.23)?
In order for a standard deviation to be defined there has to be enough data so that a bell shaped curve can be seen on a graph when plotted. You can not have a sample size of three points and get a graph. Well you can but it will not be meaningful.
The range of possible points need to be taken into consideration. So taking the wiki link in C9's 1st response http://upload.wikimedia.org/wikipedia/commons/f/f9/Comparison_standard_deviations.svg there are 2 different graphs overlaid on the same chart, showing 2 different standard deviations.
So a standard deviation is some value that represents a deviation from the average over a sample data set. If we use trackers for our poker data set we approach a perfect data set and a Standard Deviation can be defined, or agreed upon over a large sampling.
But you could be sampling cars colors as a game with you kid while you drive between Kansas City and Tulsa. She counted maybe 1000 cars and plotted them on a color basis and found that 60% were either black or white. You might determine that the 60% number constitutes a standard deviation if the numbers show that the black/white ratio was approximately equal. If so then a standard deviation could be defined as 30% (either way on the graph) and a pink Mazda with Flames (you saw 1) is not within the standard deviation, but does represent one extreme on the graph, while a yellow bug with Tall tree painted on it (also saw 1) would represent the other extreme.
Your head has exploded and your eyeballs are looking for a socket to hide in.:confus ed:
Point is that for the most part you need a bigger sample size and a definition of what you are plotting before a standard deviation can be determined and thus possibly useful.