Questions tagged [stratification]

A sampling technique in which the population of interest is partitioned into subsets ("strata") based on characteristics known at all units before sampling.

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

Should I keep discovery and validation samples separated also for subanalysis and stratification?

I am conducting an analysis on RNAseq data on two populations sampled from different geographical regions. I used population A as discovery (about 120 samples and 150 matched controls) and population ...
user avatar
  • 1
0 votes
0 answers
11 views

K-fold Stratified cross validation on a dataset with examples of variable length

I have a dataset of audio recording of variable length with large std which are heavily imbalanced in terms of total duration per class. So in stratified k-fold cross validation I would like to main ...
user avatar
  • 11
0 votes
0 answers
10 views

How to update survey weights after fixing strata membership/assignments?

Imagine we conduct a survey using stratified sampling, and after the survey closes, we find out that we had misclassified some of the respondents. They actually belong to different strata than we had ...
user avatar
1 vote
1 answer
25 views

Estimating a population total from a stratified simple random sample

I have a stratified population. I want to estimate a population total $T$ from a stratified simple random sample. I have two strategies: I compute $\displaystyle T=\sum_h N_h\bar x_h$ where $x_h$ is ...
user avatar
  • 115
4 votes
1 answer
60 views

Subclassification on a propensity and prognostic score grid with k × k subclasses, using R MatchIt

I would like to perform a joint subclassification of some data on the propensity and prognostic scores as described in this paper "On the joint use of propensity and prognostic scores in ...
user avatar
1 vote
1 answer
38 views

Cox PH controlling for multiple events

I'm working on a cox proportional hazard analysis in R using the survival package. I´m analysing covariate effects on fish movement within a study area. The study area is divided into two zones ("...
user avatar
  • 11
0 votes
1 answer
36 views

Choosing an equal number of samples from each strata - what is this called?

Suppose I have a highly skewed distribution and a proxy measurement. I use this proxy measurement to bin the samples of this distribution into different "strata". I then take N samples from ...
user avatar
0 votes
1 answer
42 views

When having non-proportional hazards, should I use stratified Cox by time or Logrank tests within periods?

My data have non-proportional hazards with clear separation. Should I handle it via stratified Cox regression or using separate Log-rank test within subsets? I will use R only to illustrate. I want to ...
user avatar
2 votes
1 answer
18 views

When computing period-specific hazard ratio using Cox, should I add variable:strata or full variable * strata?

Let's asusme I want to calculate separate hazards ratio in two periods, split like below. ...
user avatar
1 vote
1 answer
41 views

How to resample members from the population who didn't respond after the survey?

I have used stratified random sampling on population to generate the sample. Now the issue is if after the survey is conducted some of the members in the sample ...
user avatar
  • 73
0 votes
1 answer
17 views

How to calculate sampling error for proportionate sampling?

I have done sampling using Proportionate Stratified Random Sampling. The table below shows the proportion of each groups in the sample and population. This is the formula for Standard Error (...
user avatar
  • 73
1 vote
0 answers
20 views

Draw a stratified sample in panel data

Question: How can we draw a stratified sample in panel data context when the stratifying variables are not fixed over time? Background: I have panel data on workers (id) over time (t). I want to draw ...
user avatar
  • 253
0 votes
1 answer
37 views

Partitioning survival data into prognostic groups

I have survival data (n ~ 1000) with ~40% censoring and ~10% missing data. I want to partition the subjects into 4 prognostic groups based on survival. Misganow B and Vidyasagar M (Exploiting Ordinal ...
user avatar
0 votes
0 answers
25 views

Stratified sampling with unknown strata sizes

I'm in a setting where I have natural population strata (that I can infer from the samples), but I don't know the strata sizes. Are there ways to get valid confidence intervals in this setting?
user avatar
  • 1
1 vote
1 answer
12 views

What is the best way to organize the classes if we're training multiple classification models?

Let's say we have 6 classes to predict. And we want to train 2 Multinomial Logistic Regression models (one model for 3 classes and another for the other 3) instead of training one global Multinomial ...
user avatar
  • 139
0 votes
1 answer
18 views

Balance checking (using discrete variables)

Context I'm doing a field intervention, with 4 treatments and 1 control. I have done a stratified randomization beforehand to ensure that demographic characteristics (gender, age, income group) are ...
user avatar
  • 55
0 votes
0 answers
46 views

CUPED - estimation of correlation with pre treatment covariates

I came across this variance reduction technique https://www.exp-platform.com/Documents/2013-02-CUPED-ImprovingSensitivityOfControlledExperiments.pdf the main idea is using correlation with a ...
user avatar
  • 305
0 votes
0 answers
13 views

Selection bias / Stratification - How to create a sample that represents the full population

I have built and deployed multiple models, initially starting with a heuristics model, eventually moving to various iterations of machine learning models where the target is binary. For each model, ...
user avatar
  • 121
0 votes
0 answers
11 views

Stratification across 6 binary strata leading to 64 groups. Too many groups?

I am about to stratify a large population according to six binary variables. This leads to a total of 2^6 = 64 groups in total. Does stratification miss the point when you have so many groups? Or is ...
user avatar
  • 1
1 vote
0 answers
16 views

Take multiple stratified samples from

I am interested in taking three separate stratified samples from a population so that I can assign them to different treatments. I see some obvious issues with this, namely being that elements in the ...
user avatar
0 votes
0 answers
35 views

Extracting hazard ratio for subgroup from overall hazard ratio and hazard ratio of another subgroup?

Hi I have a relatively naive question here. Suppose in a clinical trial the overall HR of treatment A compared to treatment B is 0.66 (95% CI: 0.61 to 0.73). Now we perform a subgroup analysis of the ...
user avatar
1 vote
1 answer
49 views

Is it better to stratify or adjust confounders in the model with small sample size?

My questions is for Poisson models and Cox models. The context is rare/small number of events. We want to adjust for a few categorical confounders: sex, age group, baseline risk, but are not ...
user avatar
  • 475
1 vote
1 answer
74 views

Will stratified log-rank test work if there is no event in some small strata?

Since the analysis is for a rare event, it is possible that some small strata have no event. Hard to predict. Just wondering if there will be any problem. Cox PH model will have problem for sure, but ...
user avatar
  • 475
0 votes
1 answer
77 views

How do I color the points provided in cox.zph plot? [closed]

I'm trying to distinguish between the two groups in this scaled Schoenfeld residuals plot: As you can see there are two groups for test temperature which I am hypothesizing are split based on 340 C ...
user avatar
  • 13
0 votes
0 answers
36 views

Stratified Incidence Rate Estimate

I have once again a question regarding person time risk, which I just can't seem to find the proper answer to, despite reading the relevant chapters in Rothman (2012), Kirkwood & Sterne (2003), ...
user avatar
  • 1
0 votes
0 answers
116 views

Converting a code for 5-fold cross validation to stratified 5-fold cross validation for continuous target variable

Do you know how I can convert my code so it can do stratified 5-fold cross validation on a continuous target? df['score'] or y is a continuous variable. ...
user avatar
0 votes
0 answers
34 views

Test effects of multiple categorical variables in a nonlinear model

I am fitting forest biomass data to a modified version of the Chapman-Richards function using the nlsLM() function. I am curious about the impact of multiple binary predictor variables on the model. ...
user avatar
0 votes
0 answers
46 views

Stratified Randomization Guidance

Working on a dissertation, but still coming to grips with the concept of randomization (due to lack of experience), hope you can help to guide me as to whether I'm on the right track. I am working on ...
user avatar
0 votes
0 answers
27 views

Confusion between ANOVA and MANOVA

I have a dataset with participants which have used two methods (method 1 & method 2) to measure a variable with different levels (5 levels) in minutes. My intention is to see whether there are ...
user avatar
0 votes
0 answers
22 views

When do we use stratified splitting?

I have a problem with my data. I only have 59 recordings and that is not optimal for a machine learning regression pipeline. Anyway, I have multiple independent variables, most of them are in this ...
user avatar
1 vote
1 answer
566 views

Stratify a train / test split according to some categorical variables

I would like to train / test split a dataset in such a way that all categories of categorical variables are in both train and test split. I tried ( using sickit learn ) : ...
user avatar
0 votes
1 answer
130 views

Logistic regression: age covariate within age group strata

I am using logistic regression to calculate the OR of falling using certain predictors (e.g. strength), age is also a confounder. The effect of age appears linear - risk of falling incrementally ...
user avatar
  • 1
0 votes
0 answers
19 views

How to make a stratification in a penalized logistic model with the penalized function?

I use the R package "penalized" and I want to fit a stratified penalized logistic regression model. In the package vignettes, I found: It is possible to include an offset term in the model. ...
user avatar
0 votes
0 answers
11 views

Base weights/Relative weights when sampling strata change

I have survey responses from a survey where the sampling plan was stratification with sampling rates proportional to the square root of the number of households. The plan created 12 strata, and the ...
user avatar
0 votes
0 answers
38 views

Stratified sampling - use of proxy variable

For splitting of the data into train/test/val I use stratified sampling. Is it appropriate to define strata using information extracted from the dataset? E.g. use machine-learning to model proxy ...
user avatar
0 votes
0 answers
46 views

Data split using model's error

For splitting of the data into train/test/val I use stratified sampling. Then I confirm that metadata distributions represent the original dataset well enough. I want to start considering error of the ...
user avatar
0 votes
0 answers
31 views

Jensen-Shannon Distance between two Stratified Sampled Tabular Datasets

I have 100 unique joint probability mass functions with a dataset noting the prevalence of instances from each joint pmf, like this: The total amount of instances in this case would be 16,073. Each ...
user avatar
3 votes
1 answer
282 views

Precision and recall estimated with stratified sampling

I have a population including rare events (let's call them "event A") and I want to evaluate the precision and recall of a new algorithm to detect the rare events. In the actual population, ...
user avatar
  • 1,387
0 votes
0 answers
53 views

Using stratified k-fold cross validation for time series model selection

This thread talks about the use of k-fold cross-validation for time series model selection where using the rolling basis approach is recommended, but I'm wondering how one would adapt this to a ...
user avatar
0 votes
1 answer
64 views

Sample Size determination at coutry level or states levels

A country is stratified into states. A researchers wants to carry out a survey with a main requirement of state level data representation. I wonder if sample size should be determine using country ...
user avatar
  • 2,399
0 votes
0 answers
51 views

Stratified Sampling from a population according to given weights

I have a population and i want to take a sample from it in order to examine a mean of a characteristic (say $p$ the probability of having an infringment).My population is 13996 and are divided into 7 ...
user avatar
0 votes
0 answers
12 views

Balanced Allocation of Subjects to Base/Target

Lets say I'm conducting an experiment / AB test on a very volatile measure. I have a set of good estimators for this measure, which is known to me at the moment I need to assign each subject/...
user avatar
2 votes
1 answer
49 views

Stratified sampling ratio with srswor

The variable X under study have rectangular distribution with interval (a, a+ d ) the interval is divided into k equal subintervals which form k equal strata of equals sizes . From each stratum ...
user avatar
  • 447
1 vote
0 answers
224 views

Is sampling by even/odd serial numbers a simple random sample?

I'm working on a project where each member of the population has a serial number. Each serial number is issued sequentially, so smaller serial numbers reflect older records. I'm drawing a sample of ...
user avatar
1 vote
0 answers
26 views

Random draw and fraction of each class is arbitrary [closed]

I am working on a dataset with binary outcome variable $\{0,1\}$. The data provider said samples are drawn randomly from the population while the sample proportion of outcome $0$ is arbitrarily set. ...
user avatar
1 vote
1 answer
157 views

Bootstrap to control for confounding variable - sample size

I am interested in the effect of dichotomous variable A on several scores for a sample size of N = 469 (observational data). Most scores have a non-normal, asymetrical distribution. Here's the ...
user avatar
1 vote
0 answers
44 views

validation and test set definition for active learing with rare classes

Context I've got an active learning problem with an event rate of about 1%. The data is a panel, individuals over time. We have a proxy label that is highly correlated with the true label within ...
user avatar
  • 12.2k
0 votes
0 answers
240 views

What is the best cross-validation scheme for churn prediction with time varying data per client?

I am looking for the best cross-validation strategy to test the performance of a churn prediction machine learning model (classification). The model predicts if a client is going to churn in the next ...
user avatar
  • 263
0 votes
1 answer
73 views

Linear regression in very unbalanced data

I hope you can help me with this question. I have a dataset with several classes (around 25) and they are very unbalanced. Some classes have thousands of subjects, others hundreds, and others just a ...
user avatar
1 vote
1 answer
67 views

Stratification of Random Walk Jumps in Metropolis-Hastings

I aim to achieve variance reduction in Random Walk Metropolis Hastings algorithm by introducing stratification to the random walk jumps. What I have tried is to make use of Latin Hypercube Sampling in ...
user avatar
  • 143

1
2 3 4 5