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.

Filter by
Sorted by
Tagged with
0 votes
0 answers
19 views

Confusion with effect of averaging on standard deviation

First of all, I was reading a text and stuck with this part: Now regarding the above quote, I want to give two scenarios I made up to make my question clear: Scenario 1: Imagine we take N ...
cm64's user avatar
  • 101
1 vote
0 answers
10 views

I have a significant change in my outcome with the opposite sign in the lead period. Is this an issue?

Suppose I have a negative significant effect of a variable x on y. Also negative significant effect of the lag ie variable L1.x on y . But I get a positive sign significant effect on y in the future ...
Sara's user avatar
  • 11
1 vote
1 answer
23 views

which SD for Cohens D in psychotherapy pre-post study?

I'm reading a study where two groups receive two different psychotherapeutical treatments. The authors calculated Cohens D: 'In addition, we report estimates for Cohen’s d effect sizes as the adjusted ...
Johanne's user avatar
  • 11
0 votes
0 answers
11 views

Which group is more balanced? [closed]

I'm enrolled in a geopolitics course and I was doing some research on how European countries (mostly from central, south-eastern and north-eastern Europe) could be classified in terms of power and ...
user avatar
2 votes
2 answers
52 views

How can I calculate the weight of a study for meta-analysis?

I'm tasked with producing a forest plot for a meta-analysis but I've only been given the risk ratio, sample size and confidence intervals of the necessary studies. I think that I have to find the SE ...
user356816's user avatar
3 votes
0 answers
176 views

Recreating data variance from the posterior distribution

Recreating data variance from the posterior distribution Take a set of data points $(x, y)$ with (Gaussian) uncertainties $\sigma_y$ on the $y$ coordinate; they are modeled as $y \sim f(x; \alpha) + \...
Jacopo Tissino's user avatar
5 votes
3 answers
834 views

Do 95% Confidence Invervals use +- 1.96 standard error or standard deviation?

I'm trying to calculate the weight of studies for inclusion in a meta analysis as part of homework. I've been given a number of studies and their final results represented as a risk ratio with 95% ...
user356816's user avatar
0 votes
0 answers
9 views

Calculating and displaying variation of sub group responses within larger group

I have a question with 3 possible answers (yes, no, unsure), and I have the responses of two groups. Group A and group B. Group A has three sub-groups (A1, A2, A3), Group B has two sub-groups (B1, B2) ...
Dave's user avatar
  • 1
1 vote
1 answer
90 views

Calculate mean and standard deviation of the ratio of two dependent variables

I have an instrument of which I would like to understand the uncertainty on the measurements taken, so that every time that I perform a single measurement, I can apply the error obtained and therefore ...
s.cerioli's user avatar
  • 111
0 votes
0 answers
11 views

Interpreting the coefficients [duplicate]

I am reading a research paper about the effects of exposure to dirty water on test scores. The paper mentions the following: "a 10pp increase in exposure to dirty water reduce test scores by 0....
Tati Frege's user avatar
1 vote
0 answers
16 views

Drawing error bars on a position vs time chart where st. dev. is for vectors and not total position

I have the following data for a position versus time analysis. Note that the total distance is just the sum of the mean vector distances. I want to show the error bars on a chart of total distance vs ...
rdemyan's user avatar
  • 11
3 votes
0 answers
13 views

What are the expected residual standard deviations from each of the fitted models and data-generating process?

I simulate data to be analyzed using a linear mixed-effects model. It is based on an experiment with 2 levels (A and B) of a ...
Anderson's user avatar
0 votes
0 answers
19 views

converting data from geometric LS mean and confidence intervals to mean and SD

I Hope this letter finds you well. I am conducting a meta-analysis, and some of the studies have reported data in geometric least squares mean and confidence intervals, while others have presented ...
user405119's user avatar
1 vote
0 answers
58 views

Converting median absolute deviation to standard deviation

I'm working on some medical research and I'm wondering what is the most straightforward method to convert median and median absolute deviation (MAD) to mean and standard deviation. If anyone has any ...
Yomna's user avatar
  • 21
3 votes
1 answer
73 views

Why would a production process in an industry know its (population) standard deviation?

I can understand why the mean is known. I can understand that in some cases based on historical data, you have a rough idea about the variance/ standard deviation. But inherently when the real world ...
PuneUnited's user avatar
0 votes
1 answer
50 views

Conversion of log-transformed SD

In a meta-analysis of some research work, there are many situations in which the literature reported the mean values and their corresponding standard deviations in log-transformed forms. The question ...
Ahmed 's user avatar
0 votes
1 answer
94 views

calculating the 95% confidence interval, two approaches generated two different results [duplicate]

I am very puzzled by the two 95%CI results generated from the same normal-distributed dataset from the Monte Carlo method with 10000 simulations. See below figure and statistics of the Monte Carlo ...
Elizabeth's user avatar
  • 261
2 votes
2 answers
46 views

Adjusting sd for an ARMA(1,1) simulation given phi and theta

I'd like to generate model an ARMA(1,1) process with a mean of zero and a standard deviation of sigma where I specify the ARMA parameters phi and theta. How can I adjust the value of sigma in the draw ...
user111024's user avatar
0 votes
1 answer
25 views

Regarding squaring the deviations when calculating the standard deviation [duplicate]

I learned that the deviations are squared for a number of reasons. (1) They make all values positive. Otherwise the sum of the deviation would be zero. But why not just take the absolute value of the ...
Kantura's user avatar
  • 121
2 votes
1 answer
66 views

Unusual variance measure

I explore centrality measures for graphs and discretized regions. The data array (for given point) is all distances from this point to the boundary of region. At the beginning I used standard ...
lesobrod's user avatar
  • 213
1 vote
1 answer
47 views

Confidence interval for number of an event happening with a known probability

As an example, my problem is something similar to this: Lets say that you open 10 chests and each chest has a 30% chance of having an item. Calculate the confidence interval for the number of items ...
PlasmaFlare2001's user avatar
0 votes
0 answers
19 views

Stationarity and moving standard deviation

Suppose $\{X_t\}$ is stationary process. We observe a sample of $N$ observations from the process, i.e., $x_1, x_2, ..., x_N$. The stationarity property implies that the distribution doesn't change ...
Sane's user avatar
  • 185
2 votes
1 answer
78 views

How do you fit a normal distribution to this data?

I've calculated the expected frequencies by using the normal distribution chart and the frequencies given in this table. However the sum of the expected frequencies is turning out to be 67 while the ...
SVK99's user avatar
  • 23
3 votes
1 answer
230 views

Are there cases where we need to avoid the usage of IQR?

Let's consider the interquartile range (IQR), the standard deviation (SD) and the mean absolute deviation (MAD). We know that "one of the most common robust measures of scale is the interquartile ...
Ommo's user avatar
  • 270
1 vote
0 answers
30 views

Expected deviation between a theoretical discrete probability distribution and the simulated one resulting from a number of trials

Suppose we have seven colors, each associated with a theoretical probability to choose one of them. The probabilities are as follows: red ______ 0.304761904761905 blue _____ 0.304761904761905 yellow ...
TimosL's user avatar
  • 11
-1 votes
1 answer
54 views

How do I interpret a negative relative standard deviation and a relative standard deviation greater than 100 in this example?

I have the following astronomical data data1vcoord =array([[ 709.4497, 1500.3387, 1573.9434, 292.9126, 930.4643], [1423.7768, 1242.1892, 407.6168, 346.3528, 541.8568]]) data10vcoord=array([[ 718....
some_math_guy's user avatar
0 votes
0 answers
52 views

Standard deviation of standard deviation under non-normality

In this post, an unbiased estimator for the standard deviation of the standard deviation under normality is provided. I would be interested in such an estimator without the normality assumption, i.e., ...
Hiro's user avatar
  • 303
1 vote
0 answers
30 views

The variance of data set A is twice that of data set B; does this imply that the dispersion of data set A is twice that of data set B? [duplicate]

If the variance of data set A is 4, and the variance of data set B is 2, can we say that the data in set B is twice as dispersed as the data in set A? If the standard deviation of data set A is twice ...
GuoFeng Wang's user avatar
0 votes
0 answers
24 views

Using standard deviation of outcome variable as predictor in multiple linear regression

I am attempting to fit a multiple linear regression equation to a continuous, real-valued outcome variable, $Y$, using a number of predictive variables, $(X_1, X_2, ... X_n)$, i.e., $$ Y = \beta_0 + \...
stats_throwaway_1234's user avatar
0 votes
0 answers
22 views

Standard error of the mean for a questionnaire?

I have the standard deviations and means of 7 questions of a questionnaire and also the sample size. How can I calculate the standard error of the mean of the total questionnaire? I know SEM is ...
Lily's user avatar
  • 21
0 votes
0 answers
19 views

Calculate a confidence interval for the mean value of y at $(x_1,x_2) = (1.0,2.0)$ with confidence level $0.90$.

Assume a normal linear model for y with two continuous predictors $x_1,x_2$ and no intercept: $y_i=\beta_1x_{i1} +\beta_2x_{i2}+\varepsilon_i, i= 1,...,n $ You performe a corresponding linear ...
User1's user avatar
  • 1
1 vote
0 answers
53 views

SE and SD in a mixed ANOVA design

I have conducted a mixed-design ANOVA with a between-subjects factor (Group: Control Group [0] vs. Intervention Group [1]) and a within-subjects factor (Time: Baseline [0], Follow-up 1 [1], and Follow-...
Manuel Leitner's user avatar
0 votes
1 answer
32 views

How to generalize standard deviation for n-dimensional arrays?

Here is the application: I have a spectrometer and I need to test different lighting setups for it. Each time, I illuminate a fixed set of 9 color references, and I measure them. The spectrometer is ...
uz3il's user avatar
  • 1
1 vote
1 answer
49 views

Sampling for Set Covering Problem

I am a CS student, who is currently working on something related to the Set Covering Problem. To quickly describe it: There is a universe set $U = \{1,2, \dots , n\}$ and a set of subsets of $U$ ...
elson1608's user avatar
0 votes
0 answers
14 views

percentile of a normal distribution nearer to which k,k+1,k-1 standard deviations above or below the mean?

What process to use to determine whether the nth percentile of a normal distribution is closer to the k,k-1,or k+1 standard deviations above or below the mean?
jkj's user avatar
  • 1
0 votes
0 answers
19 views

Question on an algorithm picking assignments for employees

I have the following problem. I have X people that, on a weekly basis, will pick assignments out of Y different assignments. Each assignment has a different difficulty score, so at the end of each ...
Michael Chourdakis's user avatar
9 votes
3 answers
941 views

How to know the sample arithmetic mean and standard deviation if I know the mean and the deviation of the logarithm of the observations

For a sample, I know the sample size, and the mean and standard deviation of the values ​​transformed using the natural logarithm. I need to calculate the mean and standard deviation of the original ...
Luly Ch's user avatar
  • 93
1 vote
1 answer
47 views

How to transform STDEV of a numerical value to logarithmic value? [closed]

I have the following question: I have the average and STDEV values of variable. To transform this to Log10 scale, I directly apply the logarithm to the average. Can I do the same with the STDEV? ...
Zahari's user avatar
  • 11
0 votes
0 answers
28 views

Can estimated value plus one standard deviation be less than true value in a synthetic experiment?

I perform a synthetic calculation and then an inversion, that is, I have actual value in the synthetic calculation and I estimate it in the inverse problem stage. The inverse problem gives me the ...
Lager's user avatar
  • 11
0 votes
1 answer
77 views

GAMLSS: What exactly is the predicted or fitted sigma? why can't I use it to calculate z-score?

The question I have is previously posted here in detail by someone else but the main question is not answered. what exactly is the fitted sigma? Is it always standard deviation? If yes, why can't it ...
9id9's user avatar
  • 1
2 votes
1 answer
64 views

The test point’s standard deviation from the origin (ESL’s Exercise)

This is Ex.2.4 from The Elements of Statistical Learning. I don’t understand the sentence that I underline in the image. I know that $\sqrt{10}$ is approximately equal to 3.1, but I don’t know how to ...
chenqile's user avatar
0 votes
0 answers
14 views

How to compare fluctuation/standard deviation across several datasets?

I have a set of humidity and temperature readings for several different locations on the same site. I am trying to determine whether these readings are fluctuating more in certain areas. I've got the ...
clarkey000's user avatar
5 votes
1 answer
257 views

Pooled Standard deviation of means

I am reading the book Statistical Methods In Online A/B Testing. I have two questions: 1. Please Consider the scenario, an A/B test in which the variance of A and B groups are assumed to be same, and ...
yo wa's user avatar
  • 117
0 votes
1 answer
57 views

Extremely small confidence intervals and standard deviations in a clmm-model

I have a data set with an effort rating (varying in an ordinal scale from 1 to 7) as the response variable and a time point of measure (seven consecutive measures) as a fixed factor. An individual is ...
timothy's user avatar
  • 77
1 vote
1 answer
53 views

Should I apply normalization to predicted probabilities from 7 different models before computing correlation among them?

I'd like to check if there are correlation among predicted probabilities of models in a voting classifier. According to the table below, one of models, Model5, has mean 40.9% and standard deviation 46....
KAI's user avatar
  • 13
6 votes
4 answers
2k views

How to calculate standard deviation when only mean of the data and sample size is available?

Many a times it happens that you get comprehensive data at a group level and you have to compare one group against another but you don't have the data points separated. In these cases, how do we get ...
Ankita's user avatar
  • 129
2 votes
1 answer
31 views

Relation between sample standard deviation from data and maximum likelihood estimates

This is my data:- c(3164, 3362, 4435, 3542, 3578, 4529) I estimated its sample mean and standard deviation via mean & ...
Rishav Dhariwal's user avatar
1 vote
1 answer
102 views

Standard deviation of a function of random variables

I was a bit confused recently with why two jointly distributed variables will exhibit a smaller scatter as the correlation between the random variables increases (assuming only positive values for the ...
jpcgandre's user avatar
  • 403
1 vote
1 answer
112 views

How to derive a random variable's standard error and mean with its log-normal distribution estimation

I am trying to do a meta-analysis, but I met some papers which estimate the key parameter (i.e., $\alpha$) by assuming its log follows a normal distribution (i.e., $\ln(\alpha)$ ~ $N(\mu, \sigma^2)$). ...
Wu Jilong's user avatar
0 votes
0 answers
23 views

Confidence interval for standard deviation of means

I am doing some image analysis which involves: Creating a grid of square objects Calculating mean pixel values in each grid (m) Calculating standard deviation of the mean pixel values (s) Multiplying ...
user2047830's user avatar

1
2 3 4 5
41