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Questions tagged [standard-deviation]

Standard deviation (represented by the symbol sigma, σ) shows how much variation or "dispersion" exists from the average (mean, or expected value).

The standard deviation of a random variable, statistical population, data set, or probability distribution is the square root of its . A standard deviation close to 0 indicates that the data points tend to be very close to the mean (also called the expected value) of the set, while a high standard deviation indicates that the data points are spread out over a wider range of values.

The standard deviation of X is the quantity

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Standard deviation of a list

I want to find mean and standard deviation of 1st, 2nd,... digits of several (Z) lists. For example, I have A_rank=[0.8,0.4,1.2,3.7,2.6,5.8] B_rank=[0.1,2.8,3.7,2.6,5,3.4] C_Rank=[1.2,3.4,0.5,0.1,2.5,6.1] # etc (up to Z_rank )... Now I want to take…
physics_for_all
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Weighted standard deviation in NumPy

numpy.average() has a weights option, but numpy.std() does not. Does anyone have suggestions for a workaround?
YGA
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Why does numpy std() give a different result to matlab std()?

I try to convert matlab code to numpy and figured out that numpy has a different result with the std function. in matlab std([1,3,4,6]) ans = 2.0817 in numpy np.std([1,3,4,6]) 1.8027756377319946 Is this normal? And how should I handle this?
gustavgans
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Standard Deviation in LINQ

Does LINQ model the aggregate SQL function STDDEV() (standard deviation)? If not, what is the simplest / best-practices way to calculate it? Example: SELECT test_id, AVERAGE(result) avg, STDDEV(result) std FROM tests GROUP BY test_id
Steven
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Standard deviation of generic list?

I need to calculate the standard deviation of a generic list. I will try to include my code. Its a generic list with data in it. The data is mostly floats and ints. Here is my code that is relative to it without getting into to much detail:…
Tom Hangler
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How can I do standard deviation in Ruby?

I have several records with a given attribute, and I want to find the standard deviation. How do I do that?
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Standard deviation in numpy

Here is my code: import numpy as np print(np.std(np.array([0,1]))) it produces 0.5 I am confident that this is incorrect. What am I doing wrong?
user1700890
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Standard deviation javascript

I am trying to get the standard deviation of a user input string. I have as follows, but it returns the wrong value for SD. The calculation should go as follows: Sum values/number values = mean Square (sum each value-mean) Sum squares/number…
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Add error bars to show standard deviation on a plot in R

For each X-value I calculated the average Y-value and the standard deviation (sd) of each Y-value x = 1:5 y = c(1.1, 1.5, 2.9, 3.8, 5.2) sd = c(0.1, 0.3, 0.2, 0.2, 0.4) plot (x, y) How can I use the standard deviation to add error bars to each…
John Garreth
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Standard Deviation for SQLite

I've searched the SQLite docs and couldn't find anything, but I've also searched on Google and a few results appeared. Does SQLite have any built-in Standard Deviation function?
Alix Axel
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Compute average and standard deviation with awk

I have a 'file.dat' with 24 (rows) x 16 (columns) data. I have already tested the following awk script that computes de average of each column. touch aver-std.dat awk '{ for (i=1; i<=NF; i++) { sum[i]+= $i } } END { for (i=1; i<=NF; i++ ) {…
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Generate random numbers with fixed mean and sd

When generating random numbers in R using rnorm (or runif etc.), they seldom have the exact mean and SD as the distribution they are sampled from. Is there any simple one-or-two-liner that does this for me? As a preliminary solution, I've created…
Jonas Lindeløv
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Standard Deviation in R Seems to be Returning the Wrong Answer - Am I Doing Something Wrong?

A simple example of calculating standard dev: d <- c(2,4,4,4,5,5,7,9) sd(d) yields [1] 2.13809 but when done by hand, the answer is 2. What am I missing here?
Travis Rodman
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How to efficiently calculate a moving Standard Deviation

Below you can see my C# method to calculate Bollinger Bands for each point (moving average, up band, down band). As you can see this method uses 2 for loops to calculate the moving standard deviation using the moving average. It used to contain an…
Christiaan Wevers
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How to load extensions into SQLite?

I need a standard deviation function in SQLite. I have found one here: http://www.sqlite.org/contrib?orderby=date but its part of an extension file to SQLite. I've never installed one of these before and I don't know how to. I found this existing…
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