# 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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20 views

### Estimating a minimal probability of detection to choose controls and cases

I have a dataset of cattle farms, the tests with results for bovine tuberculosis and the number of cattle tested and slaughtered. Meat inspection count as a test for bovine tuberculosis too. I want to ...
8 views

### Adjustment in DLNM - case control setting

I have data in a case-control format with a 5-year lag of exposure. I want to adjust, in addition to the strata, for the number of monitoring stations used to calculate the exposure. The problem is ...
1 vote
51 views

### How to compare cases and controls after adjusting for age differences?

I have a dataset in which I have different measures (a, b, c) and two independent variables: D which is an independent binary variable representing cases (1) and controls (0), and age is another ...
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### Are predicted probabilities from logistic regression in a case-control design valid?

I have been reading about and learning how to obtain predicted probabilities from a logistic regression and if wanted, to convert these to a risk ratio. But it occurs to me that a binary outcome is ...
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1 vote
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### Is logistic regression as reliable as traditional statistical tests to measure differences between groups?

I am working on an case-control analysis where I have to report whether or not these groups are actually comparable. I have performed different statistical tests on the independent variables of ...
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### When to use paired samples tests? Specific case in clinical research

I am working on the analysis of an observational clinical study. It is basically a control/intervention study, where the intervention group received a novel protocol. In order to assess its ...
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### Stratifying a conditional logistic regression model (dataset of 1:1 matched cases controls)

Tt might be a silly question, but it is my first time doing a conditional logistic regression model in a case control study. For one table, we are stratifying our model by a variable with 2 levels. ...
33 views

### Is it valid to use unsupervised clustering to assign patients into larger groups before comparing them to controls?

I have very high-dimensional data (lipidomics) with two categories: patient/control and genetic mutation. These mutations have similar phenotypes, but they are considered different diseases. Their ...
6 views

### Any special technique for case control data where # control matches can vary per case (up to 3 matches per case)?

I have case control data, of cancer cases and healthy controls (1 row per participant). I am doing 3 rounds of matching where round 1 does 1 match per case, round two does another match per case and ...
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### How can I use propensity scores to manual match cases and controls before I begin data extraction?

I am conducting a retrospective case-control study, it is a clinical project. Initially I manually matched cases to controls of the same age and sex. It had been suggested that to have a less biased ...
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### Matched case-control study for machine learning

I am currently working on a project exploring the risk factors of liver cancer using electronic health records. Originally, we planned to use a matched case-control design due to the limited number of ...
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### Use of other ICU patients as control group

I am reviewing an article that is not yet published, so I cannot be too specific. Briefly, the authors did an unmatched case-control study. The cases were patients admitted to the ICU for a specific ...
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### Can propensity score matching be used in nested case-control study?

I'm poor with epidemiological methodology and I'm working on a study that look at the effects of a binary exposure on three time-to-event outcomes in a large cohort (general population). As the ...
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### Use of simple statistics for matched study designs

This might be a silly question, but I have always found this confusing. In a case-control study one selects participants to the study based on having or not having the outcome, in addition to some set ...
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### exact match on covariates or include in a model?

The scenario is I have a binary outcome, a treatment group variable (3 groups) and 3 covariates. It is possible to exact match all 3 covariates on 1:N from group 1:2 and group 1:3. Would you perform ...
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### Stepped wedge design to analyze healthcare intervention rolled out at different times to members?

I'm working on a pre/post analysis of longitudinal healthcare data where an intervention program was implemented on a member by member basis over a period of several years. Some eligible members ...
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### Analysis of a case-control study using ordinal logistic regression

Suppose we have data from a case-control study where for each case having had some disease or event $Y_{binary}$ a control was included that was free of $Y_{binary}$. Due to this study design we ...
15 views

### Familial risk study using case control database?

If I have a dataset with cases and controls ( cases being people with colon cancer, control are people without colon cancer), and for each case or control, there are multiple relatives linked to them ...
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### Survival analysis using as exposure a case-control study variable

I have doubts about how to correctly analyze the following study, since it is neither a nested case control nor a case-cohort study, but it is a previous matched case-control study in which the "...
24 views

### How should the prevalence be calculated when determining prevalence-adjusted PPV?

I am assessing the performance of a test for a certain disease. I have selected the disease cases and controls from a large dataset that is reasonably representative of the general population. As I ...
129 views

### Retrospective cohort study with case:control matching 1:5. Is clogit really appropriate?

I study school grades in children with brain tumors (=cases), using databases. Every case in the database has five healthy controls, matched on sex, birth year and residency. The hypothesis is that ...
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### Is it possible to have a hybrid case-control cohort study?

In a cohort study, you take 500 people and tell them to smoke cigarettes and you take 500 people and tell them not to smoke cigarettes: you then wait to see how many people in the future get cancer in ...
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### Why marginal odds in frequency matched case-control?

Let $D$ denote sampling with $D=1$ indicating subject being sampled and $D=0$ otherwise. $W$ denotes intrinsic variable of subjects, $X$ denotes exposure of interest and $Y$ denotes the binary outcome....
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### Case-control cox regression

I have a survival data on approximately 6 million observations. The "failure" I'm dealing with is very rare - about 0.5% has the event of interest. I have three questions: Can I perform a ...
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### Diff in Diff: wrong control group or wrong method?

I want to identify the causal effect of renewable energy targets on the environmental policy stringency index (I got it from OECD) for EU countries. My hypothesis is that by setting a renewable energy ...
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### Which study design is best for the following?

I have a data set in which all patients have a particular disease. The disease has three varieties labeled as 0, 1, and 2 in the data set. I want to know the association of a particular drug with this ...
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### Can selection bias lead to confounding bias?

I wonder if case-control matching will bring a new confounding bias into the matched design. In the following figure, $L$ is a confounder, $E$ is the exposure, D is the disease outcome. In the matched ...
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### Counterfactual modeling where variable is present in treatment but not control group?

I'm working with patient-level healthcare data in a pre vs. post difference-in-differences analysis where the goal is to estimate the average treatment effect for nursing care. Patients in the ...
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273 views

### Looking at how covariance/correlation between variables differs in two groups?

I have a few hundred variables representing different biomarkers. These variables have been measured in both cases and controls. The underlying units of measurement are not important, so I have ...
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1 vote
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### Example 7.16 'Case-control study' in Cox, Principles of Statistical Inference

When reading Cox's Principles of Statistical Inference (CUP, 2006), I'm struggling with the case-control study example (Example 7.16, pp. 154ff.) in §7.6.6 on pseudo-likelihood. Set-up: Random ...
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### Comparing treatment effects across groups

I created two donation campaigns, one loss framed (N:1993) and one gained framed (N:1989) I understood donations are usually veeeery low and the sample was a lot smaller than previously expected, so ...
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### Best analysis for site selection with paired data

I'm running into a problem after trying what I thought would be a simple analysis. I have 47 sites where I measured a variety of habitat characteristics (canopy cover, habitat type, percent of bare ...
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### Is it more appropriate to use random effect model in meta analysis when studies have high heterogeneity but they are not randomised?

I am using case control studies for a meta analysis. The participation selection is not random but the studies used different statistical analysis methods with their results and there is significant ...
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### Selecting correct study design and statistical analysis for my project

I am analyzing risk factors associated with surgical site infections where we want to have a 3:1 case-control study. Other than some brief lectures in my classes, the only thing we were taught about ...
1 vote
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### Why is the fully-symmetric bidirectional case-crossover design biased and the semi-symmetric design not when there are time-trends in the exposure?

I am trying to understand why the fully-symmetric bidirectional case-crossover design is biased when there are time trends in the exposure and why the semi-symmetric design is not biased? I have tried ...
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1 vote
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### Members in treatment group serve as controls for other treatment members to eliminate unmeasured confounders in pre/post observational study?

Consider a typical observational healthcare study where pre/post health outcomes among patients receiving a treatment or care program are compared to a counterfactual control group who didn't receive ...
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38 views

### Matched case control study design

I have a few questions about matched case-control study design. How do we handle matched case-control study design if you don’t have matched controls for all the cases? Would you remove unmatched case ...
1 vote
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### Calculating the confidence interval or standard error of a PPV adjusted for prevalence

I am trying to evaluate how well a disease test performs in a case-control study. In this example, the prevalence is 0.5%, and the results are below: Disease + Disease - Test + 40 (TP) 10 (FP) Test ...
1 vote
157 views

### Why we can apply conditional logistic regression to model the effect of air pollution?

In a book called 'Analysing Seasonal Health Data', the time series dataset - CVDdaily was expanded by 'casecross' function, ...
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### test for difference between matched pairs in 1:1 matched study

Background: I have a retrospective study (registry) that contains data on people with kidney transplant. Among these patients, we have a very small number of people with a specific genetic disease (n=...
39 views

### 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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### 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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### 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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128 views

### 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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294 views

### 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?
1 vote
5k views

### 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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### 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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