In Probability and Statistics, the standard deviation of a statistical population or data set is a measure of how much variation or dispersion exists from its average value. It is defined as the square root of the variance.

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Calculating Percent Variance Of Dates?

I have this problem where I have a set of data. Each data point has two values: Value1: Birthday Value2: Height Now, the problem I am faced with involves ...
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How can I calculate the standard deviation knowing an event probability and a number of trials?

I'm writing a test for a probabilistic data structure that I've implemented. Since its probabilistic, its performance is different every time, and in particular, the performance varies much more ...
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math distribution of averages and distribution of standard deviation for comparison of bytes

Let me change my question: I have a sequence of 512 numbers (these 512 numbers can have a value between 0 and 255) (in computer mode these numbers can be between 00000000 and 11111111 (bits)). For ...
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Standard error of the mean for root mean square of data

If I have a distribution of data, X, representing N samples taken during one measurement, then the mean square of X is $\bar{X^2} = \langle X^2 \rangle$, the variance of $X^2$, $\mathrm{var}(X^2)$ is ...
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Calculating mean and standard deviation of very large sample sizes

I have about 3.5GB worth of data that I need to get statistics from, all split up into about 71MB files, with an (approximately) equal number of samples. From this data, I would like to gather mean ...
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Is this true: $\mathrm{Cov}(X,Y) = \sqrt{\mathrm{Var(X)}}\sqrt{\mathrm{Var}(Y)}$?

I just want to confirm whether this is correct or not: The covariance of $X$ and $Y$ is equal to the standard deviation of $X$ times the standard deviation of $Y$. or, in mathematical notation, ...
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Can't find Standard Deviation for Continuous Random Variable

Here is my homework problem. Again, sorry for the formatting: A continuous random variable X has a symmetric distribution with mean 18. A brilliant mathematician has estimated that the probability ...
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Denominator to calculate standard deviation

I've just read something about calculating sample standard deviation. Some explanations say that it is because of degree of freedom. With a constraint that the mean should be zero, we do actually have ...
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How to calculate the expected value $E(XY)$ with known $E(X)$, $E(Y)$ and $\sigma_{i}$?

I am trying to understand the value of $\bar{x_{1} x_{2}}+E(x_{1} x_{2})$. For all $i$, $E(x_{i})$ and $\sigma_{i}$ are given. Wikipedia gives the joint probability density function: $E(XY) = \int ...
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Calculate standard deviation of merged sets with limited information (full details inside)

I have: A1: {3, 5, 6} and A2: {3, 4, 6, 8} Avg A1: 4.(6) Std.Deviation A1: 1.247 Avg A2: 5.25 Std. Deviation A2: 1.92 Merging A1 and A2, we get A12: {3, 3, 4, 5, 6, 6, 8} Avg A12: 5 Std. ...
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Calculating the “jaggedness” of a distribution

I'm sure "jaggedness" isn't the right term to use here, so please correct me. I'm trying to quantify how jagged a distribution is. For example, this is moderately jagged: distribution #1 This is ...
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Chebyshev's theorem

OK, so here's the question (not my homework - which is line segments -_-) According to Chebyshev's theorem, how many standard deviations from the mean would make up the central 60% of ...
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Sample Standard Deviation vs. Population Standard Deviation

I have an HP 50g graphing calculator and I am using it to calculate the standard deviation of some data. In the statistics calculation there is a type which can have two values: Sample Population I ...
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Is it possible to calculate the standard deviation without the samples?

Imagine I had two sets of samples. The only information I have about them is their Size Average Standard deviation Is it possible to calculate the standard deviation of a third set that is ...
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Max of multistep Gaussian walk vs max of multiple single-step Gaussian walks

Is there a relation between the max of a Gaussian random walk of 10 steps vs the max of 10 Gaussian random walks? Specifics (in Mathematica notation): ...
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Motivation behind standard deviation?

Let's take the numbers 0-10. Their mean is 5, and the individual deviations from 5 are -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5 And so the average (magnitude of) ...