# Questions tagged [pooling]

Pooling, eg for variance, is used when several groups or populations are assumed to have a common property (a common parameter value) and the information from all the groups or populations are used together to estimate that common property.

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### Expected value of [variance of sample means] is the average of [sample mean variance]?

This is drawn from Gelman et al in Regression and Other Stories: If I take $k$ independent sample proportions $p_i$ with differing sample sizes $n_i$, Gelman et al says that the observed variance of ...
1 vote
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### Does average or max pooling actually summarise the sentence?

I am working on an multi-label text classification problem at work and adapted model architecture from this notebook of Toxic Comment Classification challenge on Kaggle. I have trained the model, a ...
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### Cleaning up several crude odds ratios from several sources

Does anyone know a formula for pooling odds ratios across studies? I'm trying to do a quick pen and paper pooling of different numbers of odds ratios from different studies where I don't have the ...
1 vote
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### why some pooled variance has "average" and some just uses direct sum without avg?

say $X,Y$ are two random variables. I see courses saying $X+Y$ and $X-Y$, each has a variance of $\sigma_x^2 + \sigma_y^2.$ But, on the other hand, I also see courses talking about for $X$ and $Y,$ ...
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### A balance summary across treatments in cobalt package

I am trying to calculate standardized mean difference after multiple imputation for multiple treatments. I am using the package "cobalt" but I can not find a balance summary across treatment ...
1 vote
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### Can I use alternative pooling technique after multiple imputation?

Research problem: Comparison of means (T-test, ANOVA) between 90 countries. Analytical problem: I have a large data set of over 120 000 observations. Each observation was measures by 8 variables: 2 ...
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### Confused about pooled statistics from multiple linear regression on multiply imputed data in R

I have a dataset with 75 cases. I did multiple imputation of missing data in SPSS. I am running a multiple linear regression on the data. I have 7 binary independent variables, one continuous ...
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### Is RoI Pooling appropriate to retrieve fine details from objects of varying sizes?

I’m using a RoI Pooling after a CNN that extract features from images of varying sizes, containing defects I want to classify. The images and defects sizes range from a couple of pixels to ~100 pixels....
1 vote
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### Why is the Mean Square Between (MSB) used in 1-way ANOVA instead of total variance?

I'm having a hard time parsing the logic behind the formulas in the 1-way ANOVA. I'll first establish what I understand so far which will lead into my question. The objective of a 1-way ANOVA is to ...
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### Can I pool data sets answering identical question for different examples for moderation multiple regression analysis?

I am currently doing research on the moderation effect of the aim on factors (independent variables) that influence technology acceptance (dependent variables). My research is as follows: Group A had ...
1 vote
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### Residual standard error for multiple imputed regression

How to calculate the standard deviation of the residuals for a pooled regression? (The idea, formula and/or R code are all welcomed) As far as I understand it is the standard deviation of the ...
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### How does max pooling reduce the number of parameters to be learnt in a CNN if we already have parameter sharing?

I've been a bit confused about max pooling for a little while but I've finally understood why it provides more generalisation since you're essentially getting rid of less useful information and ...
1 vote
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### With 2-sample bootstrap testing, why pool treatment with control samples?

I have data from a randomized experiment. Members of the treatment group received a treatment, members of the control group did not. I want to test differences in distributions of ordinal outcomes ...
1 vote
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### Different Ways to Calculate the Pooled Means

I have the following question about the properties of individual means vs. pooled means. To illustrate my example, I will use the R programming language. Suppose we have measurements from two ...
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### About pooling layer in CNN for landmark detection purpose

I was reading about landmark detection using CNN from this website. In landmark detection, the output is the x-y coordinate of the object that we look for. In CNN, as far as I know, we use the pooling ...
1 vote
237 views

### Rubin's Rule of pooled confidence interval

Rubin's Rule for multiple imputation states that you are to construct a single interval after pooling into a single set of estimates and standard errors:  \bar{\theta} \pm t_{df,1-\frac{\alpha}{2}}*...
225 views

### Difference between Pooled variance and Combined variance

Could someone explain for me what the difference between Combined variance and pooled variance is? I have couple of groups (more than 2) with different sample size, I want to calculate the overall ...
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### Converting unstandardised regression coefficients to Cohen's d for meta-analysis

I am conducting a meta-analysis of Cohen's d and some raw effect sizes are unstandardised regression coefficients. Of these unstandardised regression coefficients: Some are based on a binary ...
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### Precision of a pooled variance

Say you want to calculate the pooled within-sample variance and you can have 20 observations in total. We can assume the variances are equal in each sample. When designing the experiment, what will ...
1 vote
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### Test for Subgroup Difference Compared to Test for Moderator

I have performed a proportional meta-analysis to evaluate the rate of procedural success for two medical procedures. The two procedures comprise the two subgroups in my meta-analysis (FNA and FNB). I ...
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### Confidence Interval of an Average

Consider I have 20 samples from each of 10 batches resulting in 200 samples total. If I take a parameter I'm trying to estimate and calculate the confidence interval using all 200 samples pooled ...
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### Pooling in a Meta Analysis

I am looking to pool data for adverse events for a meta analysis and I wanted to see if my plan made sense I want to pool my AE together based on the Clavien Dindo categorizations, as this will make ...
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### Do Convolutional Layers Pool data?

Sorry for the trivial question but considering this example in the image attached doesn't the conv layer pool data by summing them? What I am asking is if this images describes a subset where a conv ...
1 vote
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### Asked to create data set where magnitude of paired t-test statistic is very large, but pooled t-test statistic is small. Can't find any resources [closed]

It seems almost impossible to make these tests diverge by much. I have tried making the variance for one distribution much larger, or much smaller. I have found a data set where the paired is a good ...
1 vote
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### Pooling Two Samples to a Single Sample

Let us say we draw 10 sample values from a given (continuous) population. However, the values tend to be very different than expected, so that we suspect that there might have been an error with the ...
1 vote
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### Can I pool together data from two seperate RCTs of the same intervention when I have access to both datasets? If so, what analysis is appropriate?

Background I have available the data from: A parallel arm RCT of Intervention A compared to a control group that was conducted several years ago. The primary outcome is a difference in the post-...
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### Pooling estimates from different models into a pseudo-hierarchical model

I don't know if the question title makes sense, so I'll try to explain what I mean below. I have roughly 100 ERGM models (social networks) that, for the sake of argument, are parametrised in the same ...
1 vote
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### Staggered Average and Standard Deviation of incomplete dataset

I have an AxBxC matrix of measurements, from which an arbitrarily-sized-and-distributed number of measurements have been deemed invalid and removed (i.e. that matrix contains a mostly random ...
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### Is it reasonable to calculate a T-test or Cohen's d with one group's sample size, mean and standard deviation being averaged or pooled?

This is my data: year 1: n, mean, sd year 2: n, mean, sd year 3: n, mean, sd year 4: n, mean, sd year 5: no data year 6: n, mean, sd (special event happened) Sample sizes, means and standard ...
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### Pooled (or combined?) variance - is it suitable to use in the below scenario?

I have a dataset with measurements and their deviations from nominal value. These measurements have been made on 3 different categories of a component. The components differ in physical properties (...
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### How do I decide if it's ok to pool data?

I have biodiversity data (fish species, and their individual length, through electrofishing) from 8 different stretches of the same river, for 7 different seasons. We would like to see if it's ok to ...
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### Can you calculate pooled standard deviation from just the sample standard deviation?

For a meta analysis, we are calculating cohen's d from data reported on published articles. For a specific article, only standard error (SE) and mean difference (between treatment and condition) are ...
1 vote
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### Looking for somewhat pooling between average and maximum pooling

In the textbook Dive into Deep, there is a question: Is there another operation between average and maximum pooling that you could consider (hint: recall the softmax)? Why might it not be so popular? (...
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### How to calculate aggregate standard deviation for composite scores in a meta-analysis

I wonder if someone would be kind and able to provide guidance/suggestions on a stats issue that myself and colleagues are trying to handle while performing a systematic review and meta-analysis. In ...
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### Pooling variance of two samples with sample means and sample variance [duplicate]

I am new to this so I don't have enough reputation to comment on the original post here. I have a similar problem with equal weighting, and have n = m = 3. I believe this means I need to use sample ...
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### Pooling of data

I am doing some secondary analyses. I am looking to combine similar surveys from different countries in a region (sub-Saharan Africa) to be able to detect more subtle differences between my ...
32 views

### Pooling and Chow-test

I have a dataset containing weekly observations of three variables; sales, price and assortment, for 10 different brands in 12 different grocery chains. The observations go over 209 weeks for all ...
1 vote
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### Network meta-analysis with trials of different follow-up time [closed]

0 I am trying to do a network meta-analysis, and calculating anticipated absolute differences, I have seen other papers generating anticipated absolute differences for treatment for x number of years. ...
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### Pooled Variance from two Variables' SD, but no correlation?

Is there any way to calculate a pooled variance in a within subjects design when I have the SDs and sample size, but no correlation between X and Y? I'm trying to calculate an effect size using single ...
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### Why is the cohen's d effect-size from this study so different from the value I've computed manually?

In this study , they estimate an overall cohen's d effect-size of .70; however, when I try to compute the cohen's d using their means/stds, I get a much smaller effect-size of .47. Am I doing ...
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### Simple question on A/B testing

Hi there I have a question that I am confused as how to answer. So I have a balanced dataset of 500 observations split between 2 groups. 250 are a control group and 250 are an experimental group. The ...
1 vote
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### Calculating pooled estimates after manipulating datasets

After I imputed two datasets, the two datasets are synthesized via statistical matching. With the synthesized data, I tried to pool estimates but got errors as below. ...
271 views

### Advantage of within transformation over pooled OLS with dummies?

First, apply the within transformation (fixed effects transformation) on a panel data set. Then, apply pooled OLS with dummies for each cross-sectional unit on the same panel data set. When you ...
1 vote
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### Local translational invariance for content when pooling or downsampling

Suppose I do 2x2 pooling with stride 2x2, and I can do as much zero-padding as I want. Ordinary pooling is local and not fully translation invariant, because it is dependent on image boundaries. If I ...
1 vote