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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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Pooled Covariance Matrix with very different amount of samples per class

I have a dataset with 10 classes, and want to estimate the covariance. It turns out that due to numerical stabilitiy, it is much better to use a pooled covariance matrix. Suppose I have $N$ samples ...
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CNN: correct way of reducing dimensionality of last feature maps

I want to reduce the features of the last convolutional layer of my CNN before connecting it to a dense layer to minimize the risk of overfitting. Lets say the feature maps of the last layer have the ...
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With lme4, is it possible to weight group-level random effects by similarity?

I'm creating a model with two group-level random effects: district (factor) and age (factor) and a response, ...
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Understanding the relationship between multiple variables

Having troubles interpreting the results of my pool() function I know what everything means except for the estimate, d and riv columns: ...
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3 Level Hierarchical Models in STATA; Null model fails to converge

3 Level Hierarchical Models in STATA; Null model failed to converge About the Dataset I am working with DHS (Demographic and Health Survey Data) data. DHS uses a two-stage cluster sampling process. ...
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Standardisation (normalising) for feature scaling in non-logged data for within transformation model

I wonder if someone could provide an insight for my case. I am interested in normalising my data to obtain unitless state that will allow me to use them in a quadratic model (not translog). Based on ...
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Weighting and Clustering in Pooled Data Analysis

I am working with DHS (Demographic and Health Survey) data. I have pooled data from about 25 countries taking 2 most recent waves from each country. My dependent variable is neghaz (negative of height ...
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19 views

Proof that the pooled sample variance is biased when paired comparison is not used when it should be

Given the model for what is meant to be a paired comparison design: $y_{ij} = \mu_i + \beta_j + \epsilon_{ij}$ $i = 1,2; j= 1, 2, ..., 10$ Eg. An experiment comparing the different in mean hardness ...
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How to calculate pooled deviance explained from gam model fitted with multiple imputation data set?

I fitted gam model using mgcv package with multiple imputation data set. I need to calculate the combined overall deviance explained. Is the approach used in combining r-square from multiple ...
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R Panel Data: Difference between Pooling OLS and Fixed Effect with only “individual” effect

I just estimated my paneldata with Pooled OLS or with the Fixed Effect approach. When using FE with the effect="individual" I get a higher adjusted R^2 than using FE with effect="twoways". So I would ...
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77 views

Is there an R function that performs LASSO regression on multiple imputed datasets and pools results together?

I have a dataset with 283 observation of 60 variables. My outcome variable is dichotomous (Diagnosis) and can be either of two diseases. I am comparing two types of diseases that often show much ...
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Combining point prevalence estimates and their confidence intervals

I have some health survey data from multiple years. This includes the estimated prevalence of a flu vaccination in a population, then number of people surveyed, and the high/low confidence intervals. ...
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Dynamic Pooled OLS: does it make sense?

I have data on 25 countries for about 35 years. I want to estimate a POLS as I am not looking for a causal interpretation but just sttistical correlation between two phenomena. That's why I will not ...
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143 views

1D CNN for time series regression without pooling layers?

I am working on a prognostics task, where I predict the Remaining Useful Life of some equipment (i.e.: time steps remaining until failure). In order to do that, I use multivariate time series sensor ...
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1answer
25 views

Difference between pooled variance equations

I'm currently doing A-level Further Maths A2. I've seen two different equations to calculate the estimate of pooled variance. I do not know when to use which and what makes each significantly ...
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Simple mean or weighted mean of Fisher z-transformed correlation coefficients

I need to perform the average of a set of correlation coefficients $\rho_i$ with $i=1,\ldots,m$. I follow the standard prescription: apply the Fisher z-transformation to my $\rho_i$ ($z_i$ are the z-...
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Panel Data: correlation between individual effects and variables

Is it possible to see if there is a correlation between any variable and the individual effects just by looking at the coefficients and standard-errors of an OLS, RE and FE functions?
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Why do we neglect the additive interaction in bi-linear pooling?

In bilinear pooling we use the multiplicative interaction between elements of the vector but what about the additive interaction(the usual feed-forward layer)? I mean in bilinear pooling, we don't ...
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bias estimating the proportion in pooled population

Assuming we want to estimate the proportion of success and there are two stages. We will move to stage 2 only when the number of success is greater than equal to a threshold (say 5) in stage 1. And we ...
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23 views

pooled GEV return level estimation

Let’s suppose I have 4 AMAX time series of 40 years each one, they could be eg wind speeds from 4 meteorological stations in a given region. The time series have been normalised. I want to fit a GEV ...
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39 views

Pooled regression vs. average over individual time series models

I have a standard prediction problem in social science where the data set is a pooled data set (i.e., time series of cross sections where each sample can differ and is de-trended, $y_{t+1} = \beta X_t ...
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What are the advantages of a random effects model versus a pooled OLS regression with cluster–robust standard errors?

Both models allow for explanatory variables that are time-invariant. I had thought that the advantage of a random effects model might be related to the fact that random effects models mitigate ...
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35 views

what is the standard error for hypothesis testing of two proportions using a z-test?

Let's say we are evaluating two algorithms. Algorithm 1 gets p1 = 80% conversion Algorithm 2 gets p2 = 85% conversion The two sample sizes are ...
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Test for Homoskedasticity and endogeneity in Panel data with Pooled OLS estimation

Which tests are valid to test for: 1) Homoskedasticity 2) Endogeneity in a Pooled OLS model built on Panel data?
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When to pool the sums of squares in an ANOVA model

I had used a two way ANOVA (with interaction) For EDA, the plot of means suggested an interaction between main effects However, the null hypothesis of an interaction between the main effects was not ...
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Pooled standard error of an estimate that is the product of combined estimates

I have two independent mean estimates (with SE and sample size) that I want to multiply to create a combined estimate. I'm having trouble interpreting what to use for sample size in the combined ...
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Pooled standard deviation with single observation in one group

I'm calculating grand mean and pooled standard deviation across students course passing (binary 0=failed, 1=passed). My data set has 70 students, with observations ranging from 1 to 29 per student. In ...
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Pooling homogenous studies vs. using meta-analysis/bayesian

I am working with a student who has collected about 300 participants for his thesis. After collecting 100 participants, he analyzed the data. I had just recently read of a "mini-meta-analysis" ...
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21 views

Pooling Results from Bootstrapped Samples (Adjusted R-square and variable significance)

My manager is interested in using Adjusted r-squared to evaluate models and want to know how much does each predictor contribute to the adjusted r-squared to the final model. However, due to an ...
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29 views

How to combine observational studies

I am trying to show the releationship between a drug and an outcome in a particular setting. Using a systematic review, I have found 18 studies addressing this topic. Among those, the highest quality ...
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118 views

Predicting elastic-net values with glmnet after multiple imputation - problem with pooling

I'm having a problem to predict values after I ran elastic net with multiple imputation with MICE. After I run MICE imputation, I have m imputed data sets. I then run an elastic net model on each one ...
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344 views

Connection between time dummies and time fixed effects

If i use time dummies in a OLS pooled regression, does it imply time fixed effects? Maybe to clear things up: 1)There is a pooled time -series-cross-section regression, the equation uses time ...
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554 views

Proof to obtain pooled variance equation [closed]

I was checking the definition of pooled variance, and although I think it makes sense intuitively, I was wondering how can one obtain that estimator. For the case of only one group, I understand the ...
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Correlation with data that show an effect of the factor that they are being pooled across

I am analyzing concentrations of a chemical in a plant species and am interested in understanding how the concentrations vary between tissues and across sites. An ...
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Short Sentence Generation using CNNs

I am investigating whether building a classifier for sentence classification using CNN can be used for sentence generation. Say, we are classifying news articles' titles (classes such as sports, ...
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92 views

Asymptotic Variance for Pooled OLS

I am trying to prove, under the assumption $E[u_t^2x_t^Tx_t]=\underbrace{E[u_t^2]}_{\sigma^2}E[x_t^Tx_t]$, that the $$AVar[\beta_{POLS}]=\sigma^2 E[x_t^Tx_t]^{-1}$$ My result: $$\begin{eqnarray}AVar[...
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Pooled variance for post hoc tests for contingency table $\chi^{2}$ tests

The 2-by-2 contingency table test provides an alternate hypothesis testing approach to the $z$ test for proportion difference. Conveniently enough, a 2-by-k contingency table test provides an omnibus ...
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Why global average pooling is able to work correctly?

In Network in Newtork, section 3.2, talks about global average pooling (GAP). In my understanding, GAP averages every value of (x,y) coordinate in 1 feature map into 1 value, then send this value to ...
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176 views

Meta-Analyzing Dependent Effect Sizes (Log Response Ratios)--Is Averaging Effects An Acceptable Solution?

Given k studies, for each computing a log response ratio $L$ and variance $v$ following the Hegdes et al., 1999 equations: $$L = ln(R) = ln(\bar{X}_{E})- ln(\bar{X}_{C})$$ $$v = \frac{(SD_{E})^2}{n_{...
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81 views

Formula for pooling means, variances

We are performing an inter-comparison experiment for three devices that can measure concentration (cells/mL). We take one solution and run it through each device, and we compute mean concentration and ...
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When is it appropriate to pool trials within subjects for statistical comparisons?

Usually I have small number of subjects (e.g., 4-6 rodents) and I record electrophysiological activity during presentation of a stimulus or performance of a task. A general question that arises when ...
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186 views

Is it possible for a global attention pooling layer to have “channels”?

I'm trying to implement a neural model described in a paper, and I've encountered the following sentences: Due to smaller sizes no pooling is used in the encoder except for global pooling, for ...
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68 views

Pool analysis or meta analysis for one arm studies

I am new to pooled analysis. Currently I received results of several observational studies. Each study is a clinical trial on patients who have the same disease of interest. In each study, all ...
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1answer
414 views

SGD learning in CNN gets stuck when using a max pooling layer (x-post from DataScience) [closed]

I'm working on a CNN library for a university project and I'm having some trouble implementing the backpropagation through the max pooling layer. Please note that the whole thing was built from ...
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1answer
85 views

How can I pool correlations?

I'm measuring a phenomenon over several days. On any particular day, the phenomenon is well correlated. I was wondering how I could pool the correlations over several days to get a single estimate ...
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1answer
228 views

Pooled variance of correlated samples

I got two samples originating from the following multivariate $$ (X_1, X_2) \sim \mathcal{N}\left(0, \left[ \begin{matrix} \sigma^2 & \rho\sigma^2 \\ \rho\sigma^2 & \sigma^2 \end{matrix} \...
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956 views

How to calculate confidence interval for main and interaction effects? (2^3 factorial design with no replicates)

I have a three-factor (1, 2, 3), two-level (-, +) factorial design shown below (contrast coefficients for interaction effects and response parameters shown here as well). The overall goal is to ...
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What does pooled variance “actually” mean?

I am a noob in statistics, so could you guys please help me out here. My question is the following: What does pooled variance actually mean? When I look for a formula for pooled variance in the ...