All Questions
10 questions
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Is the variance of the mean of a set of possibly dependent random variables less than the average of their respective variances? [closed]
Is the variance of the mean of a set of possibly dependent random variables less than or equal to the average of their respective variances?
Mathematically, given random variables $X_1, X_2, ..., X_n$ ...
- 139
0
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0
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178
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Calculating the Standard Deviation of Estimates from a Uniform Distribution
I was looking at this question on Sufficient Statistics and the Uniform Distribution: https://math.stackexchange.com/questions/1359183/why-should-we-care-about-sufficient-statistics
In this question, ...
2
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2
answers
246
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Expression of $E[(X-a)^3]$ as a function of $\operatorname{Var}(X)$ and/or $\sigma_x$
Just a question:
I would be able to express $\mathrm{E}\left[(X-a)^{3}\right]$ as a function of $\sigma_x$
and/or $\sigma_x^2$, with $a$ a constant (surely $\mathrm{E}\left[X\right]$ terms should ...
user226073
1
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3
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740
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How to measure good or bad luck in roulette
I want to analyze and represent the performance of a bet (X numbers out of 37 total roulette numbers) for a series of spins (N spins).
For example, let's say that I choose 5 numbers (my bet) and these ...
- 123
2
votes
1
answer
239
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Will change in standard deviation impact covariance?
If we increase the degree of standard deviation of one variable, does it affect covariance of two variables?
Example, two variables are there, A & B, the covariance of A & B is 100, and the ...
5
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4
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6k
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Practical meaning of expected value (mean value), variance and standard deviation?
I have a question about concepts:
Expected value (mean value) - $μ$
Variance - $σ^2$
Standard deviation - $σ$
What is the practical meaning of these common concepts of the probability theory and ...
- 379
4
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4
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3k
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Odds of a number appearing only one time in 500 spins on roulette
I recently observed a roulette wheel where one number appeared only once in five hundred spins. This is an American roulette wheel with 0 and 00, so the odds of any number hitting should be 1/38.
I ...
- 41
0
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1
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29
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Spread on x-axis around an extremum
I am working on a graph that has Power (Watts) on the x-axis and Frequency (not Hertz here, more like the probability that we consume that much power) on the y-axis.
What I would like to do with it ...
- 141
1
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1
answer
2k
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Find standard deviation of arbitrary game with multiple payouts
This earlier question asked how to get a 5.76 standard deviation for a single number bet on Roulette. The answer gave the formula, but unfortunately, the formula doesn't easily generalize to more than ...
- 113
3
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1
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6k
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What is the probability that a girl is taller than a boy, with boys ~N(68, 4.5) and girls ~N(62, 3.2)?
"Given that boys' heights are distributed normally $\mathcal{N}(68$ inches, $4.5$ inches$)$ and girls are distributed $\mathcal{N}(62$ inches, $3.2$ inches$)$, what is the probability that a girl ...
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