Questions tagged [case-control-study]

An observational study in which two existing groups differing in outcome are identified and compared on the basis of some supposed causal attribute.

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How to treat a subject's possible preference

I have some animal preference data and would like some advice on treating it correctly. There are 10 subjects, and two trials dealing with a barrier product. The subjects were allowed to select one of ...
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Problems due to sampling data from the same case patients multiple times?

Please imagine the following scenario: In a predictive modeling task for the probability that a hospital patient will encounter a certain medical event, all available data is split into cases and ...
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Propensity score matching in a case-control study: can the number of matches per patient be correlated with a matching variable?

Say I am trying to investigate the association between antidepressants and achieving recovery in a depression programme. I have an observational cohort of depressed patients enrolled in the programme ...
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Is a conditional logistic regression on a 1:M case-control equivalent to a unconditional model with "centered" data?

I've been studying conditional logistic regression using this book, and it states that for 1 case- M control studies the maximum likelihood estimation of the conditional logistic regression can be ...
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Analysis of a continuous outcome for a treatment in a very small sample size (6 treatment, 5 controls) while adjusting for confounding variables

I have to assess changes in a continuous outcome after a treatment, however, my sample size is very small (6 treatment, 5 controls). Also, I need to adjust for 4-5 confounding variables such as age, ...
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Can we perform ordinal regression on n<30 using bootstrapping?

The data collected aims to analyze an institute's performance and they have an only a small number of employees working, I want to establish a model using ordinal regression can it be possible?
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Logistic regression in retrospective studies

In Agresti's Categorical Data Analysis, it is explained that logistic regression can be used for case control studies where $Y$ is fixed and $X$ is random. Let $Z$ indicate whether a subject is ...
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Limits to how many control and treatment subjects may be paired in propensity score matching?

I'm working on a difference-in-differences project where we're matching up to 5 control subjects to each treatment subject using a combination of techniques to estimate treatment effects (ATT): exact, ...
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Balance diagnostics: Why not measure post-matching balance **within** matched treatment-control pairs?

I understand there are a number of techniques for evaluating post-matching balance at the covariate level: standardized mean difference (SMD), variance ratios, and empirical CDF statistics. Are there ...
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Does "ds" have any statistical meaning?

I was reading a research paper and was wondering if "ds= .56 to .63" was a quantitative means of measuring the study, or if it was related to referencing?
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P-value of chi-square test of independence

I need help understanding chi2 independence test scipy.stats.chi2_contingency. Let's assume I have two samples (of different sizes) of a categorical variable with 3 possible outcomes (1, 2, 3): Counts ...
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What statistical test / analysis should I use?

I have conducted a RCT with two arm treatment. I would like to compare the difference on an 8 question pain scale between groups. Data has been completed at baseline and every week for 5 or 6 weeks ...
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Is parallel trends assumption necessary in difference-in-differences analysis?

Reading the literature on the subject, I haven't encountered clear reasoning why the parallel trends assumption must hold. In fact, there have been recent papers on ways to relax this assumption (see ...
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What to do if there are not enough controls per case?

I conduct a case-control study (matching by age) where I have a ratio of 1:2, i.e., 2 controls per case. However, this ratio is not sufficient for all cases. Example: If I have 30 cases with 70 years, ...
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How to calculate number needed to treat for case-crossover study design?

I'm relatively new to epidemiological methods. I'm trying to assess a program where I have access to administrative data that can be put into a case-crossover study design. I'm trying to assess the ...
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How to design experiment and holdout for two types of treatment at the same time

Let's say there are two types of treatment, namely treatment A and treatment B. A subject can be in one of these categories: get treatment A and then treatment B. get treatment B and then treatment A....
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Is it preferable to perform multiple case-control comparisons rather than a regression model to estimate variable effects on an outcome?

It's often the case when doing inferential health statistics on observational data that we want to estimate the unbiased effects of demographic variables (race, sex, age) in addition to other factors ...
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How to calculate sample size for a biomarker discovery nested case-control study (approach by M. Pepe)?

I'm about to design a nested case-control study in which I will try to identify a biomarker (or biomarker panel) from protein expression levels (determined with mass spectronomy). I've got a cohort of ...
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Retrospective cohort study and case control study

What study would best suit looking at the association between low birthweight and later academic performance? Note - 1000 low birth weight children and 3000 normal birthweight children were included ...
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Simulating data for case-control study

I am trying run a simulation-based sample size calculation for case control data. The parameters that I'm working with are: 1:1 case:control ratio 30% prevalence of exposure in controls So, the ...
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Logistic regression for case-control studies

If I have designed a study where participants from 3 disease groups of fixed size were being sampled and suppose the three groups A, B and C are of sizes n_A=50, n_B=50 and n_C=100. Group A is a ...
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Extreme differences between control group and affected group

I am reviewing an article and cannot be overly specific but it involves one group of people with a medical condition and another group without it; the dependent variables are various mental health ...
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Interaction with a matching variable (time) in conditional logistic regression

Short version: I want to look at the interaction between an explanatory variable and a matching variable in my conditional logistic regression. Is that possible? I'm doing a case-control study on risk ...
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Choosing control group for RCT

Imagine the following situation to illustrate my question: We want to run an RCT to test whether policy2, combined with policy1, ...
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Can diagnostic accuracy measures be used in case-control studies?

I want to assess the predictive ability of biomarkers in a nested case-control study. The primary analysis with use conditional regression. I’d some questions: 1)Can I determine the AUC, sensitivity ...
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After the sample size calculation what is the next step in clinical trials?

Suppose I want to test if drug A is effective to reduce the levels of some disease. From previous studies, the drug is estimated to reduce the disease by 0.5 units (mean difference) with a standard ...
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Minimum sample size and power test

Suppose I have access to data on the energy consumption of a city with a population of 30000 persons. Imagine I want to test a new technology of smart energy, i.e if the energy consumption decreases ...
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Case-Control Study Design for Longitudinal Analysis

I am designing a study in which I want to examine the relationship between a disease - major depression - and five exposures of interest: healthy/unhealthy diet, daily exercise hours, general outlook ...
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How to combine the multiple days of a dose for meta analysis

I want to do a meta-analysis on case-control animal studies. But the problems is, a dose contain multiple days and shows their effects at each day like after 7, 14, 28 days. In a meta-analysis, I show ...
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Single SQL query for case-control matching [closed]

I am running a case-control study for which I wish to choose 5 controls for each case, stratifying by age, sex, and date of measurement. Each case or control has a unique serial number and the ...
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Statistical analysis for comparing expertise levels between 3 groups

I hope you are all safe and healthy considering the current climate. I was wondering if someone could help with a statistical dilemma I have on my hands. I am trying to explore whether IQ tests can ...
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Logistic regression, about 1 and 0'es

I'm doing a logistic regression in R and I'd like to know how to select the dependent and independent variables, Logistic regression is done when the dependent variable of interest should be 1 ( like ...
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Case control sampling strategy for longitudinal analysis

Does it sound plausible to use a case-control sampling strategy to then address a longitudinal question? For example, let's say I have a population of diabetics (N=100) and non-diabetics (N=9999). I ...
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Can exact tests compare groups from case-cohort studies?

I have reviewed several helpful threads most related to my question and many thanks to the authors. The first thread suggests odds ratio is valid for cohort studies, but risk ratios or hazard ratios ...
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Using prior information for a GAM smooth function to reduce standard errors

I have some data that I want to model in a GAM. However, there are few observations, generally leading to high standard errors. ...
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Matching when there are missing data

In a treatment effects framework, I have a control and treatment group with some covariates on which to match (I'm using nearest-neighbor method). The control group has a no missing data, but some ...
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Controlled Intervention Before/After

I have an intervention that I'd like to determine the effect of (before/after). All of the data has been divided into a treatment or control group. The issue is that the treatment/intervention took ...
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Can someone explain as simply as possible why you use OR in retrospective studies while using RR in prospective studies?

I've really tried to understand why you can't use relative risk (RR) in retrospective studies but for some reason I can't understand it. Has anyone been able to convey this simply to their students?
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Valid conclusions from simple case?

If I have an experiment documenting the recovery of 1,000 patients who were given access to a medication. Results: MEN taking the drug. 2 out of 2 recover (100% recovery). MEN not taking the drug. ...
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Proper Average Treatment Effect estimators (and standard errors) for Generalized Linear Models with log link?

What is the proper formula for estimating the Average Treatment Effect with a simple main effects generalized linear model? My first pass at defining the Average Treatment Effect for a GLM with a log ...
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Finding best conditional logistic regression model with unbalanced strata

I am interested in fitting the best possible model for the case of conditional logistic regression where the strata are unbalanced. Although I have not seen it specified, but I understand that there ...
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The appropriate match ratio between case and controls: the obsession with 1:5 [duplicate]

My intention with this question is to collect relevant references or literature for a recurrent methodological approach commonly applied in health research. The main question is: what is the ...
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Is it possible to calculate odds ratio(95% CI) for only control group?

The original data contains scores of case/control group. The score is the number of risk alleles multiplied by the regression coefficient for SNP. So in the data, case samples have higher score than ...
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Case-Control study with 1:N matching and a continuous outcome variable

I'm interested to compare cases with controls on a continuous outcome variable. The cases are people with a certain disease, while the controls are matched on various criteria (age, sex, etc) thought ...
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Checking if treatment is effective without control group

I am experimenting with few treatments to see which one is effective. I do not have luxury of control group to compare against. In such scenario, is there any method to see if the treatment has been ...
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Sample Size for Case-Control Study

We wanted to perform a case-control study and used the calculation below. Using alpha = 0.05, beta = 0.20, p1-p2 = 0.003, and a ratio of controls to cases of 1000:1, we came up with a sample size of ...
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Question about design choice of Enbrel RWE study

Statisticians in 2015 analyzed real world data, hundreds of thousands of medical insurance claims involving people with rheumatoid arthritis and other inflammatory diseases, according to the Pfizer ...
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Meta-analysis for case control studies

I am working on a method of meta-analysis for case-control studies by stratifying cases and controls then calculating the effect size. Can I do a meta-analysis including only case-control studies for ...
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Correlation analysis using a case-control study-based data

I have a case-control study-based data. This is a data to confirm the association of hypertension and BMI. The definition of the case group (hypertension group) is SBP(systolic blood pressure)>=140. ...
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Difference between N case studies and case series with N patients

Is there any reason to treat data from multiple case studies differently from data from a case series that reports data on multiple patients? Assuming the case-series intervention was the same for ...
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