Questions tagged [cluster-sample]

Cluster sampling is a sampling design in which the observation units have to be grouped together for logistical reasons (e.g., students clustered in schools or households clustered in a geographic area). Typically, cluster samples are multistage samples, so geographic areas are selected in the first stage and households in the subsequent stage.

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Agreement in clustered sample data

I have analyzed several data curves from a group of patients (16 curves per patient) with different analysis methods and want to test for the agreement of the methods. So far, I have neglected the ...
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GEE all clusters of size 1 have same outcome

I have a large population of patients and hospitalization (>1 million) information. I'm trying to look at the relationships between various predictors and hospital re-admissions within 30 days. The ...
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544 views

Power calculation for cluster-level analysis in cluster randomized trials

I would like to solve for $\pi_1$ in equation 7.14 of Hayes and Moulton's Cluster Randomized Trials. I can't for the life of me remember how to do so. Here is a link to the equation. $$ c = 2\;+\;(z_{\...
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50 views

Identifying a single cluster from multiple clusters per customer

Although I have worked out several possible approaches, am curious if anyone has a better best practice to recommend? I have a large set of customer events (online behavior: 1 mil. records, 20 ...
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399 views

geeglm not recognizing clusters

I am fitting a geeglm model and it is not recognizing the clustering. my model is ...
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25 views

Single DV with repeated/clustered measurements of IV

I have an analytical dilemma wherein I have a single DV with multiple categorical and continuous IVs (one of which is a continuous IV that has multiple measurements across time). I'm not sure the best ...
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Clustering structured data

Does clustering make sense at structured data? I have a sales data set from a retail company. The data is structured into Product Lines, Product Groups and Colors and Articles. I wanted to make a ...
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396 views

Effect of modelling matched data via fixed effects

A simple approach to handling matched or clustered data would be fit a regression model that includes fixed effects corresponding to matched pair or cluster ID. For example, with 1:1 matching on $N$ ...
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Why doesn't clustering bias the standard errors in this very simple simulation?

I simulate a very simple model with one regressor and a random intercept: $$y_{ij} = \beta_0 + \beta_1x_{1,ij} + u_j + \epsilon_{ij}$$ I run model <- lm(y ~ x1) ...
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How to estimate variance for identical & fraternal twins with a mixed model

I am using the twins data from OpenMx and am curious to estimate the empirical covariance structure for BMI differences in monozygous and dizygous twins: ...
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550 views

Sample size calculation for Cluster randomized trial

In the following Paper by Clare Rutterford, Andrew Copas and Sandra Eldridge, the following formula is given for sample size calculation: assuming the following properties: • m - number of clusters ...
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97 views

Which bootstrap for small set of independent data?

I am thinking which bootstrap to choose for studying MIT-BIH arrythmia database (44 patients) in time-domain and Fourier-domain. I need to find a variable which can allow me to determine ...
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151 views

For boostrapping: stratified or cluster sampling?

I am trying to apply bootstrapping on several regression models to obtain SEs of parameters. My question is about preparing the bootstrapping samples in proper manner. The data I am working on are ...
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171 views

Power calculation for multiple level clustering / randomization using simulations R

I am trying to calculate power of the following design: -Treatment is randomized over a small number of clusters (1st level clustering=regions) -Within each region we randomly select villages (...
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Calculating needed sample size for two stage stratified cluster sample

We want to carry out a survey to assess perceptions of quality and access to medical education of last year students. Based on our research, we have decided that a two stage stratified cluster sample ...
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92 views

Cluster weights in PROC GLMPOWER

I am doing power analyses in SAS using PROC GLMPOWER to solve for a total sample size (N Total). I have clustered data (Ward method), to account for variability. There are 4 clusters of varying sample ...
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184 views

When do sample size calculations need to adjust for clustering?

I am aware that sample size calculations for cluster RCTs must adjust for clustered data. I would like to understand better if such adjustment might be necessary for other study designs. For instance, ...
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860 views

Sample Size Calculation for Cluster Sampling

I'm being asked to calculate a necessary sample size for a cluster sampling protocol. I don't have much experience with cluster sampling, so thought I'd come here. The situation is as follows: 1) ...
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IPD meta-analysis: need to weight regression and population level estimates?

Using individual patient data (IPD) from various studies, do I need to weight observations in a meta-analysis? Each study used a two-stage cluster sampling design with uniform samples per cluster and ...
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50 views

Power Calculation in R for CRCT with outcome on individual level

I would welcome any help with computing power calculations for cluster randomised control trial and specifying the code in R for this. I've been trying to use clusterPower package but any R package ...
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139 views

Clusters in Cluster Analysis and Sampling

In Cluster Analysis, clusters are usually "homogenous within" (that is, units within a cluster are close to each other ) and "heterogeneous within" (or clusters far from each other). In Survey ...
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52 views

Linear mixed effects model for twins

I have a dataset which contains data on MZ twins, DZ twins and unrelated individuals. The predictor and response are binomial variables and the effect size of the predictor may vary depending on the ...
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279 views

GEE with independent working correlation matrix vs GLM on twin pairs yield different confidence intervals

I have a data set with about 2000 twin pairs and want to apply a logistic regression to it while taking account of the correlated observations (twin pairs = clusters). I use the GEE procedure in SPSS. ...
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23 views

How can I account for clusters at different observational levels than the independent variable?

My independent variable, $Y_i$, has observations at the group-year level. However, I know $Y_i$ is not independent for all $i$ because the same individuals will be in a group for several years in a ...
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45 views

Sample size calculation of a national study

We want to conduct a national study to estimate a prevalence of certain disease. we still confused about the sample size calculation and the criteria of selecting a representative sample. First: is ...
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How do I determine the necessary sample size for this data?

I want to estimate enlistment of African American soldiers in the Union Army (during the American Civil War) by county in order to regress this variable on county-level post-war outcomes. I ultimately ...
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82 views

How to calculate a sample size in the case of a stratified 3 degrees sample design ?

I am trying to calculate the sample size (and the repartition between PSUs and SSUs) needed to obtain an estimation of a proportion (that I assume to de around 50%) with a 0.05 standard error in the ...
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Expectation Value of Standard Deviation from “k” Closest Samples

The question that I'm am trying to answer is how to determine the expectation value of the standard deviation of 'k' closest samples to value 'A'. The standard deviation and mean of the underlying ...
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69 views

Is controlling for cluster good enough in an analysis with a clustered sample?

I'm trying to understand how sampling design affects analyses and I'm a little confused about how to adjust for clustering. From what I've read, when you have a clustered sample you are supposed to ...
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236 views

one sample t test for clustered data in R

How shall I do one sample t test for clustered data? For instance, I have N = 100 number of observations, which are obtained from 5 different regions. I'd like to test whether the outcome y is ...
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227 views

Cluster Sampling involving Design Effect

A survey of residents is performed using cluster sampling. The design effect is 3.00. From the survey, the estimated proportion of people who are happy with their insurance company is 0.42 with a ...
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31 views

Significance of proportions in clustered data

I have data for multiple homes, each of which spends a certain amount of time in Condition 1 and then a certain amount of time in Condition 2. While in these two conditions, there are a variable ...
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380 views

Cluster Sampling problem

I'm using Sharon Lohr's book to self-study, and there is no solution to this problem. I just wanted to make sure I'm computing the values correctly. Question: The new candy Green Globules is being ...
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386 views

Cross validation with unequal sample size for the left out sets

I am trying to do cross validation on several (20) subsets of samples, which all have unequal sample size. I cannot subsample so that sizes are equal. Example: batch 1: 500 samples batch 2: 400 ...
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74 views

Clustered samples in case control studies

In health systems research, in which data is usually gathered from practices or clinics, why are case control studies often designed without correction for design effect?
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360 views

Computing confidence interval of clustered data

Hi, this is the first time I am posting a question here so I apologize if my questions are not written in the proper manner and corrections will be welcomed. I have a dataset in which each instance ...
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39 views

Measuring multiple samples from a specific point vs multiple samples each from a random point

I have been reading about sampling and I am wondering about the following: If your interested in measuring the rate of change of your population, ideally I assume you would choose a point at random in ...
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How to know whether a random effect or a cluster effect is necessary for a mixed effect logistic regression?

I have 8 variables in my model out of which I have a group which is definitely not a fixed effect. I tried checking the random effect on the basis of the log-likehood test and it seems significant. I ...
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67 views

Confidence intervals for survey-weighted Poisson regression in R where counts are totals of the survey weights

Forgive me if this is a very basic question. I am using a large database of healthcare encounters that uses a stratified sampling approach. Each row in the database is a sampled encounter, and has a ...
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42 views

Calculating Sample Size for Cluster Randomized Trials with Person-level or Cluster-Level Outcomes

I have been looking for a formula to calculate the estimated sample size for a two-level cluster-randomized controlled trial with cluster-level outcome data. To my reading, several authors do not make ...
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23 views

Sufficient sampling size for logistical regression observational data

As a part of my master thesis, I'm conducting an observational study of journalists' background and the effect of this on the approach to a certain case study. I have a fixed number of observations/...
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93 views

R Survey Package and One Stage Cluster Sample

I have a data set with 450 clusters of unequal size. I wish to select a probability proportionate sample of clusters with replacement (PPSWR) and measure an attribute within each of the sampled ...
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520 views

How to estimate survey data at cluster level in a stratified clustering survey design?

While estimating from the survey data involving stratification & clustering survey design and using survey package of r, is it possible to estimate at the cluster level? For eg; for following ...
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273 views

How to detect clustering or related anomalies in cross-section data

I have a cross-section of 100,000 individuals and information on their age. I suspect that there may be clustering by age or that the sample exhibits behavior that there would be two groups, the old ...
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Ideas for sampling design

I have a data base of schools per district and the number of teachers per school. I want to select a sample where between 1 an 10 schools are selected in each district. Once a school is selected, the ...
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95 views

How would I factor study design into relative risk?

I'm comparing various conditions versus some disease for a large stratified/clustered dataset which purports to account for the entire population after weighting -- hence the use of RR instead of OR. ...
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161 views

Cluster Analysis - Assign Data to Cluster

I am new to cluster analysis and doing it for first time. I have created the 6 clusters by using Weka tools like this (for 4 attributes): ...