First, I want to apologize for the error in my previous post. I have spent
way more time playing video poker since I retired than I have studying
statistics. I also realize that this particular issue is not earth-shaking,
but may be of interest to some who are trying to learn. Cogno is quite
correct when he states that standard deviation (SD) is the square root of
variance, and not the other way around. I should have caught this error in
the original post as well as the procedural one.
Second, I want to point out that the calculations I made were based on the
two assumptions of the original poster: A) That variance is the square root
of SD and B) That STP adds 51% to the SD of the original game. Since
assumption A is false, the results of my computations were of no value, even
though the computations were mathematically correct.
Third, I would like to offer the calculation procedure using the correct
assumptions.For 9/6 JoB the variance is 19.51, so the SD is the square root
of this or 4.417. The SD for the new game (STP) then is 151% of
4.417 which equals 6.670. The new variance then is the square of 6.670 or
44.48. A simpler procedure would be to multiply the variance for the
original game by the square of 1.51. This simplified formula then should
hold as long as assumption B ( above ) holds true. Since this is close to
the 44.50 given in the original post on the topic, I'm sure that the author
knew what he was doing, but a person using his assumptions exactly as stated
could not have reached this correct answer.
Fourth, math teachers are often accused of only caring about the correct
answer. In fact, the correct answer arrived at by faulty assumptions,
procedures or logic can have disastrous effect on the learning process.
Example: A student of 9/6 JoB holds a single 10 and draws a royal flush.
What dangerous conclusions might be drawn? While there is ( in a rational
world ) very limited market for the wrong answer, the primary goal in the
math class ( which this forum often becomes ) is learning logic and sound
procedure as well as accurate definitions.
Fifth, Although Cogno made a correct observation regarding my error, he made
no attempt to explain the correct method for obtaining the desired result.
While sarcasm is often amusing ( I often resort to it myself ) it is seldom
constructive.
Sixth, I respect and appreciate the other contributors to this forum,
especially regular ones like Cogno, who take their time to share with us.
And finally, Should this devolve into a pissing match, my further posts on
the topic are highly unlikely ... highly.
Thank you,
Joel P.
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