Questions tagged [mean]
The expected value of a random variable; or a location measure for a sample.
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Given two rvs $X$ and $Y$, if $X Y = Z$, is it possible to change the mean and sd of $X$ without changing the mean and sd of $Y$ and $Z$
I have two lognormal rvs $X$ and $Y$, and a third rv $Z$ which is the product of the former two. I know the mean and standard deviation of the three.
Is it possible to calculate an alternative pair of ...
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Calculating proportion
I have a dataset of 10 people who share the cost of a service at the end of each month. The cost of the service is constant. Is there a fair way to split the cost of the service such that the ...
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Diffrence in probability distributions of seperated groups
If I were to measure some quantitavie metric of a sample population and record its mean, and then I were to split by random selection all members of the population into two groups of equal size and ...
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Descriptive Statistics for Zero-Inflated Dataset
Just as titled, I'm curious as to what should you choose to represent a measure of central tendency for a zero-inflated vector or such. My background says go "mean" if normally distributed, &...
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With more labelled samples in a grouped dataset, to check the correlation with another, is it better to duplicate samples or take the means? [closed]
Another issue is that dataset with more labels in groups, they have less deviation intra groups vs inter groups. So I could take the means of them (the 'second' index), or the whole label means (the '...
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Multiple correlations across subjects
I have a bunch of data where I am recording two variables across time for many subjects: velocity of the right hand, and intensity of the speech.
For each of my 20 subjects, I have ~30 recordings of ~...
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A T-test for difference of means and normality assumption [duplicate]
I am a little bit confused about normality assumption in T-Test for difference of two independent means. My reasoning now as follows:
If the distribution of the populations are non-normal, it's ok as ...
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Is there a difference between Principal Component and weighted mean using PC loadings? How to get Principal Component on scale of original variables?
I was interested in doing a Principal Component analysis but returning a Principal Component on the scale of the original variables. Principal component analysis in R defaults to scaling and centering,...
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What would be the optimal model for continous data across 5 time points?
We are searching for the best model to represent continuous data of gene expression logFC (Y-axis) across 5 time points (X-axis), where the trend line would follow the mean expression on each day. ...
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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 ...
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Demeaning binary variable
I was confused regarding fixed effects regression model. Suppose I have a panel dataset with data on firms across several years. Introducing firm fixed effects and estimating deviations from means (...
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How to report a difference in means - Demographics
First of all sorry for the question, I'm having a hard time with statistics :)
I have conducted a survey for my thesis and am currently analyzing and reporting the results. At the end of my survey, I ...
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Paired sample t-test to compare the accuracy of missing data imputation methods
I have an assignment to compare an original data set (N = 100, 14 variables, 5 of which are nominal) with complete values to another version of the same data set with missing values imputed from 3 ...
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Computing the Mean of Twice-Measured Ordinal Variables for Individual Participants: Is it Valid?
I am conducting a 2x2 study with ordinal independent variables. Participants are asked to rate two different instances of the same independent variable condition. For instance, participants in the '...
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How to explain discrepancies between contrast estimates and mean differences?
(I'm working with R but the core of my question is about statistics.)
I'm using a quasibinomial model in R with a dependent variable and several independent variables (both numeric and dummy variables)...
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Is it acceptable to take the mean of a bunch of median values?
I use a Bayesian latent variable model to construct a time series cross-sectional measure of corruption for all countries in the world from 1960 to 2010. For each country-year observation, I obtain a ...
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R summarize predicted value by groups from multiple datasets
I ran mice function and generated 3 mice imputed datasetes.
I have a nonstandard model that is not supported by with function so. I used this example and ...
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Estimating the mean of a Poisson process from data
My data shows the daily number of logins per person over the last three months.
I am modelling the number of events per person per day as a Poisson process. I am interested in estimating the ...
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The Tsallis entropy of generalized Gaussian distribution
I would like to discuss the computation of the Tsallis entropy for the generalized Gaussian distribution. From the paper in the link https://www.sciencedirect.com/science/article/pii/S0167947322000822....
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Covariance between sample mean and sample standard deviation
I am trying to figure out the covariance between sample mean and sample standard deviation. The only related post I can find here is this: asymptotic covariance between mean and standard deviation and ...
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Covariance between sample mean and sample variance
I am trying to figure out the covariance between sample mean and sample variance from a population. We DO NOT know whether the population is normal (if it's normal, then the covariance is zero between ...
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Error between average of averages and true average [closed]
It is known that the average of averages can yield an incorrect result as compared to the true average.
The classroom example comes to mind: if the test results of class A is [50, 60, 100], class B is ...
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Aggregating metrics at parent
I have a model with several independent variables/metrics that each additionally has a corresponding unit, pre-defined upper/lower bounds and a desired value.
Now I wish to compute some basic ...
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Why are the AD, ACME and Prop. Mediated identical for control and treated groups in mediation analysis?
I have conducted a basic mediation analysis using mediation::mediate. My treatment variable (X) is a binary variable with two groups. My mediator and outcome variables are continuous. I also have a ...
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Can I use Welch's t-test on proportion data?
I have conducted a Welch t-test to see if the group means in a school's average progress 8 scores (a measure of education attainment) are different for rural and urban schools.
I also have data on the ...
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Calculate confidence interval of mean difference - in R?
I'd like to calculate the confidence interval of the mean difference. I know that you could potentially use the t.test function in R for this but I can't use the original data, of which the means have ...
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Understanding the Weighted Bootstrap
I have recently learned about the idea that it is possible to bootstrap "weighted" data - for example, suppose we have:
A set of sample means : $\bar{x}_1,\bar{x}_2,\ldots,\bar{x}_k$
The ...
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How to convert standard error of the mean (SEM) into a percentage change
I have performed a t-test between groups, but I only have Mean, SEM, and N. Now I would like to look at the percentage change between these two groups, and compare this percentage change to another ...
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Can any quantity be bootstrapped?
Suppose we have the median incomes of 150 different countries (in each country, the median income was calculated on a sample of people) - we don't have the individual incomes of each person in these ...
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Mean of Medians? Median of Means?
This is a question I have wondered about for a long time and have never been able to find a full mathematical explanation behind this.
Suppose there are 100 countries. As an experiment:
We give Person ...
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When can I average the averages?
Let's be straightforward to my case. I'm building a matchmaking system where it produces groups of players. Each player has a weight that is obtained from his/her skill and experience. A group is good ...
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How to impute the std deviation of a sample using the pooled mean and standard deviation of similar samples?
I want to perform a meta-regression based on the mean changes from baseline values.In one of the studies, the standard deviation has not been mentioned. How can I impute the value of the missed ...
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Why is there different Geometric Least Square Means for same treatment?
According to the study protocol, we used the MIXED model technique (in SAS) to estimate the ratio for example C vs A , C vs D, and its 90% confidence interval. However, in the ANOVA output, for ...
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Mean-centerinfg for logit values?
I have a question regarding the logistic growth model. Can proportion values that have been converted into logit be mean-centered? When we calculate the actual difference value between two proportion ...
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Can Ordinal data have a difference in mean if one is comparing the same group at different points in time?
I'm currently looking at a study where Ordinal scales are used to compare the effects of drugs on Alzheimer at different time points throughout treatment https://www.ncbi.nlm.nih.gov/pmc/articles/...
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von Mises-Fisher distributions and Gauss characterization of Gaussians
We can read in Jaynes' Probability Theory: The Logic of Science that the family of Gaussian densities
$$ f_{m}(x) = \frac{1}{\sqrt{2 \pi \sigma^2}}e^{-\frac{(x-m)^2}{2\sigma^2}} $$
with $m\in \mathbb{...
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Simple unbiased mean estimator for censored data
Suppose I have an i.i.d. random sample of size $n$ s.t. $X_i \sim \mathcal{N}(\mu, \sigma^2)$ for all $i$. But suppose my observed sample is left censored, such that any $x_i$ observation is replaced ...
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How to set the age range, median, and mean age
Thank you for reading my question.
I used the clustering method to classify the age of the houses.
This graph show the clustered results.
I should to get the age range, mean age, and median age for ...
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Calculating SD for Change in time
I'm conducting a meta-analysis on weight change (T2 - T0) between Group 1 and Group 2. The data I have typically looks like this:
Weight (kg)
Group 1 (n=15) | Group 2 (n=14)
T0 65.31±16.49 | 59.06±...
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Combining velocity measurements which are accurate in different ranges
I am using two different methods to measure velocities, which can be positive, negative or zero. Method A accurately measures low velocities and no velocity, but not highly positive or highly negative ...
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How to prove that if the bootstrapped sample means are approximately normal, then the sample mean is approximately normal?
I'm considering the scenario described in this question, namely:
we have IID $X_i, i = 1, ..., n$ sampled from a population with mean $\mu$, variance $\sigma^2$ unknown
the goal is to put a ...
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Difficulty in identifying outliers beyond limits
I have a various files, all containing data at 1-minute interval. File structure is as follows where D/T represents Date-Time, C1 and C2 are like constants in this task.
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Suppose we know $\mu_X<\mu_Y$. How can that information be used to improve estimates of the mean of $X$ and $Y$
Suppose there are two distributions which we know nothing about except that the mean of second is greater than the first and each can be sampled.
Intuitively, the estimate of both means should be able ...
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The right way to find average change in percentages
I want find how much percentage changed on average. Am I doing it the right way?
Say I start with value 100 and change the value by some percentage
Can I say that the avg. change is 2.46 % (adding ...
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Neural network regression - predicting mean and standard deviation
I have a dataset where for the same input, you get slightly varying results. In the final dataset I am using there are 4 input/output pairs for every input where the input is exactly the same but the ...
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Take mean of variables for linear regression
I am currently doing multiple linear regression analysis and was wondering if it would be legit to compute a new single variable by taking the mean out of four variables that are measuring the same ...
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How should mean and standard deviation be tracked over time
Say we have a process where not all data is available at the beginning, and we need to estimate mean and standard deviation to normalize them, what would be the update for the tracking variables?
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Test hypothesis for one median, std or percentile using boostrap
I'm using Bootstrap for testing the mean by creating samples centered around H0
...
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Calculation of standard deviation for 1/x (changed unit)
I have a report of a machine in which it is documented how many parts it has produced each day in the last year. From this I could calculate the mean with its standard deviation in [parts/day].
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Expected number of correct answers to exam if I guess at each question
I do an exam with $12$ questions. There are $5$ possible answers to each of the $12$ questions.
Is this the expected number of correct answers if I guess answer for each question? $$\frac15 \times 12 ...
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