Questions tagged [standard-deviation]

Standard deviation is the square root of the variance of a random variable, an estimator thereof, or a similar measure of the spread of a batch of data.

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How to calculate the error of the estimated population mean?

I need to know how to define an error estimate for the estimated population mean. I have a set of scalar data which represents multiple time response measurements of the same sensor from independent ...
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How to calculate how frequently a number will fall inside a range in a flat distribution?

Basically assume I have a random number generator with a flat distribution from 1-100. If I get repeated sample sets from this of variable size (sample_size), and I group the output into arbitrary ...
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Normal distributon mean and standard deviation for group

My task is given below and I'm stuck on 3 step (probably I made a mistake in 2 step as I'm not 100% sure what m means there and what I have to calculate. My code is: ...
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How to combine latitude + longitude standard deviation to get a 2D standard deviation?

I'm currently working with data from a GPS antenna, which returns: latitude standard deviation (meters) longitude standard deviation (meters) I'd like to get a "single" value out of ...
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How do I propagate the error in the elements of a set through to the mean of the elements?

I need to understand how to propagate the errors in the elements of a set through to the mean of the set and correctly determine the estimate for the error value of the mean. I am designing an ...
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Calculating the standard error for the ratio of 2 random variables?

I have 2 40x10 matrices, $X$ and $Y$. Each row represents a sample, and each column represents a different trial. Its OK to assume that $X$ and $Y$ are random normal variables if that's relevant. I ...
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Standard deviation of difference of two data vectors

I have two data vectors A, B where each row of the data represents a pair. I am looking to find standard deviation of A - B. The firs approach: stdev(A - B) Second ...
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Dealing with sdev in percentage calculations that exceed 1

Good day, I have the following problem: I have been given a customer engagement analysis from a sample of 30 individuals to visualize. Our company presents the customers with material to consume and ...
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How to deal with standard deviation using percentage values

I have the following issue: I have calculated a mean value of customer engagement over a sample of 30 individuals. We present them with material to consume and calculate the engagement as (number of ...
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How do I calculate Correlation Coefficient using Mean Absolute Deviation?

I am trying to calculate Pearson's Correlation Coefficient using the product of the Mean Absolute Deviations (MADs) of my two lists as denominators instead of the Standard Deviations. Effectively, ...
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Selecting a target number [closed]

Problem Statement I am working with a dataset of customers containing past 3 years quarterly data of different branches. The data set looks like this ...
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Calculating spread (standard deviation or CV) for ranges of values

Due to data suppression/confidentiality, I only have ranges of values, not individual data points. I have the sample sizes, the percentage of acres that receive ranges of fertilizer application rates, ...
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Estimating distribution characteristics from characteristics of multiple samples

Definition Suppose that $X \sim D(\mu, \sigma)$, where $D$ is a 1D distribution (generating from $\mathbb{R}$) with mean $\mu$ and stddev $\sigma$. If I sample $X$ (the random variable) $M\times N$ ...
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Is it taboo to take the standard deviation of a very small list of numbers?

I read through a similar question: Is it meaningful to calculate standard deviation of two numbers? However, this was largely focusing on error bars. If I have five numbers, let's say: ...
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Any index/parameter to evaluate std error and std deviation?

I saw there are tons of good questions on standard error y deviation. I read many of them and I think I got the point. However I am still not sure that showing one over the other is correct. Unless ...
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Value of Covariance term too high : multiple attempts to solve it

I have a first array 5x1 Bias_sp_fid and a second one 5x1 Bias_ph_fid (fid for fiducial). I ...
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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 ...
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Statistical Responses/tests for Yes/No, Pre/Post surveys

I am completing a research paper regarding clinician adherence to a protocol. One of the questions is whether or not they use adjuctive therapy to the treatment. I have a pre and post survey, yes/no ...
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Sample or Population Standard Deviation (SD) While Calculating SD Regarding All Variables' Variance Inflation Factor Values

What Was I Trying to Do? I was calculating the Variance Inflation Factors (VIFs) of all variables in a data set. Then, I was interested to calculate the mean and standard deviation (SD) of VIFs of all ...
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Insignificant impulse response functions

Anyone with time series analysis experience? I am building a VAR model with 6 endogenous variables and 3500 observations for each variable (I have used daily frequencies in my time series model). I ...
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When a scalar variable is normally distributed, how does one estimate the standard deviation of this underlying distribution using linear models?

I have a sample of N for two variables X and Y, where Y can be assumed as equal to bX + $\epsilon$, b ~ N($\mu$,$\sigma$), and $\epsilon$ ~ N(0,1) Using a simple linear regression, I tried to ...
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How to find standard deviation when sample size changes in R [closed]

How do you find the standard deviation for tails in R, when the sample size changes from n=100 to n=50 when tossing a coin?
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Measures of central tendency and dispersion of multimodal distributions

I want to make the argument that the mean is not an optimal description of the central tendency of a multimodal distribution and neither is the standard deviation an optimal measure of the dispersion ...
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Interpreting divergence between standard error and observed standard deviation of population

I have a simple dataframe. Users come to my website and sign up for a trial. I consider each sign up as a conversion. But my conversion rate is fluctuating wildly every day even though I have about ...
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Explanation on why SD is better than MD

Trying to understand why Standard Deviation (SD) is widely accepted as a measure of dispersion instead of Mean Deviation (MD) $\frac {1}{N}\sum|X-\mu|$. Revisiting a 90-year-old debate: the advantages ...
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Measuring variability in blood pressure in a repeated measures design with different time intervals between study visits

I have repeated measures on blood pressure for a lot of patients, measured at different intervals (table below). I want my standard deviation to reflect that a large deviation in blood pressure ...
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Estimate how many values fall below a specific deviation using the empirical rule

I'm trying to estimate how many values fall within a portion of the standard deviation Lets say I have: A sample size of 100 and Average of 50. and a start deviation of 10. Using the Empirical Rule ...
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Looking for a measure of variance of variance?

I was hoping you would be able to help me identify the statistic I am looking for, or point me in the right direction. Is there a statistical measure that will represent variance of variance (or s.d. ...
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How do I use a baseline of fitness data to score a competition between individuals who do not have similar abilities

Over 10 days the participants exercised as much as they could to get a baseline for each individual's capabilities. They were given a score based on time spent with their heart rate above X. I want ...
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What I have this rare output value of variance and standart deviation functions in numpy? [duplicate]

Hell i have nonsense values of variance and standart deviation in numpy. this documentation no make sense with this sample. https://numpy.org/doc/stable/reference/generated/numpy.std.html youtube ...
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How much of the variation in X*Y is explained by the variation in X?

I would like to determine what percentage of the variation in XY is explained by the variation in X and Y individually. In other words, is there a metric of variation for which unknown_var_metric(XY) =...
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For data that follows an exponential trend, is there a single equation to relate standard deviation, mean, and sample size?

Essentially, is there an equation that consists of mean, sample size, and standard deviation (or standard error of the mean) whereby I could know two of the three values and calculate the third ...
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Obtain standard deviation for normalized-difference-index from known standard deviation of inputs

I have a simple normalized difference index of type index = (a - b) / (a + b) The data I have available: mean of a std of a mean of b std of b From mean(a) and ...
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Measure of variation for subjective matter (Pitch in spoken voice)

We try to calculate the pitch variation of a particular speaker over time to then evaluate whether he was speaking monotonous or not. Standard Deviation and Coefficient of Variation have not proven to ...
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Explaining why exceptional outcomes occur more often in small populations

As noted by Scott E. Page, the author of the book The Model Thinker, that smaller populations perform better (and worse) than larger population. As per my understanding, he contributes this to two ...
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Why Welford’s method is not widely used in statistical library

I just learned about Welford’s method to compute standard deviation using only one pass. However, when I checked the source code of some statistical libraries (e.g., R stats and Numpy), they both use ...
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Can the standard deviation of a variable be estimated from many different measurements with small N?

I am not sure how to search for this, so if you can please point me to relevant posts or literature, or if you can give your expert view on the matter, it would be great. I'll try to cut a long story ...
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Standard deviation of error (SDE) application

There are standard deviation, standard error (SE), standard error of mean (SEM), then there is standard deviation of error (SDE) intended as a measure of error variability used in device measurement ...
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Calculating the weighted standard deviation of multiple standard deviations

I got the following example data: 'Iteration_1': {'mean': 1980, 'min': 876, 'max': 3034, 'standard_deviation': 695 'median': 1883 'total_n': 20}, 'Iteration_2': {'mean': 1808 'min': 1543 'max': 2074 '...
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Can a P-value be calculated with these 4 statistics?

This is all you know. There are two farming plots, they are adjacent to each other, with the same soil type and irrigation methods. Yields for the two plots are available for 15 years. Plot 1 has an ...
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Why does the Standard deviation formula when using coded data not account for the addition or subtraction of coded part

When we code data from x to x-b the standard deviation formula is: Sd(x)=sd(x-b)= (sum of(x-b)^2)/n - (sum of (x-b)/n)^2 Why do they not use (sum of (x-b)/n +b )^2 for the second part since this is ...
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Standard Deviation calculations [duplicate]

C[Calculate the mean and standard deviation of each investment, assume that both returns come from independent samples, are both normally distributed and that the (true but unknown) variances are the ...
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Calculating MEAN and STANDARD DEVIATION confussed

[] ** calculate the mean and standard deviation of each investment, assume that both returns come from independent samples, are both normally distributed and that the (true but unknown) variances are ...
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Finding standard deviation of formula with three variables

Suppose we have the formula $Y = \frac{2WV^{2}}{\pi D^2}\hspace{1cm}$(1) where: w = weight variable, v = velocity variable, d = diameter variable we want to find $SD(Y)$ the solution which was ...
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(G)ARCH: Squared Residuals vs Absolute Residuals

I estimated a GARCH model to forecast the variance of a variable conditional on past information. I evaluated the forecast by comparing the squared forecast error, i.e. the squared value by which the ...
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Derive standard deviation of residuals about fitted regression line

Let $(x_i, y_i)$ be a sample point used to estimating the regression line, $y=\alpha + \beta x$. If $y=a+bx$ is the estimated regression line, and $\hat{e_i}$ = residual for the point $(x_i, y_i)$ ...
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What is the “prior standard deviation of the modelled predictive means” and how do you calculate this?

In the book Regression and Other Stories (Gelman et al., 2021, p. 208), there is an example where a multi-linear regression model has: $26$ coefficients; standardised predictors with mean $0$ and ...
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Have I calculated the normal distribution standard deviation equivalent correctly from this the skew normal variance?

Purpose of this work: I have two datasets. I am trying to match one person from dataset A to one person from dataset B, for every person in dataset A. These are being matched on the age difference ...
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Standard deviation of optima found by an optimization algorithm

I recently developed a local optimization algorithm to tackle a question of interest to me. Usually, my algorithm returns a variety of plausible optima, several of which are often found more than once....

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