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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Is this a case control or a retrospective cohort study? What are the biases? [on hold]

BACKGROUND: Black Americans have higher mortality from breast cancer than white Americans. This study explores the influence of socioeconomic factors and black race on treatment and mortality for ...
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12 views

Control group and bias

I am trying to determine the percentage of patients who will continue to refill a drug on a timely basis. I have data for each month how many patients (as a fraction of those who started the treatment ...
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8 views

How to calculate OR and p-value for allele combination on different chromosomes

I have one question to calculate genetic risk for combination of multiple single nucleotide polymorphisms (SNP). In case-control study dealing with two or more SNPs, is there popular method to ...
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38 views

What type of study?

I calculated inter-rater reliability for a medical test. We applied the test on both healthy people and people with a specific disease and then two raters interpreted the test. Can I call this study a ...
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9 views

Case control study - possible options

Lets assume that I have a two populations ${A, B}$ and they are different in terms of some features such as country. Both samples have fairly large number of ...
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28 views

Multivariate Analyses of Matched Case-Control Data

I'm a medical student and working on some public health research. I'm new to the forum and I am completely stumped right now trying to figure out how to handle the issue of multivariate analysis of ...
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41 views

linear regression model in case-control study

if I'm conducting a case-control study and I want to use linear regression for a continuous dependent outcome. Do I have to separate cases from controls or I have to enter the full cohort to the model?...
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1answer
46 views

Should cohort studies in diagnosis research be age-matched?

It is clear that cohort studies in epidemiology should be matched for such variables as age, gender, etc. However, cross-sectional cohort studies may also be used to assess the accuracy of a new ...
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16 views

Minimum sample size to establish a cutoff point

I conducted a case-control study (obese and normal body weight). I want to conduct ROC curve between my variables to establish a cutoff point for vitamin depending on insulin resistance risk. Does it ...
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18 views

reference group in logistic regression

I'm conducting a case control study. Can I use the 75th percentile of the control distribution as a reference group to compare it with the case group? and does anyone have a good reference for this?
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16 views

Conditional logistic regression interpretation and implementation

I'm conducting a case control study studying the effect of pro inflammatory biomarkers on insulin resistance among obese (cases) as compared with normal body weight (controls. cases and controls were ...
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66 views

Determining hold out group size for purposes of verifying lift

I have the following scenario: We want to send out an email blast to existing members to promote an upsell. We are quite positive the email blast will increase the number of upsells, but we are ...
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1answer
49 views

logistic regression model when the correlation is insignificant

I'm new to statistics. I want to ask if i have two continuous variables with insignificant correlation between them, but when I converted one of them into binary outcome (according to its cutoff point)...
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26 views

Adjusting confounders

I'm conducting a case-control study consisted of 32 males and 35 females matched by age and gender with controls. Do I have to control for gender when I do the statistical analysis?
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149 views

Goodness-of-fit for conditional (case-control) logistic regression models

What is the appropriate/best way to assess goodness-of-fit for a conditional (or case-control) logistic regression model? The Hosmer-Lemeshow test for logistic regression does not apply to conditional ...
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77 views

Which test to use for matched case-control setting with repeated measures and a continuous outcome?

I apologize if this question has already been answered in the past; I was unable to find a similar setting by searching. I have a study with 2 groups (rare cases and their siblings, N=13+13). Each ...
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19 views

Determine number of excess events in survival analysis

I have run a survival analysis on two group of people that saw different ads during an ad campaign. I would like to calculate the number of excess events that occurred due to the exposure to the ad. ...
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27 views

how to convert quantitative variables into binary variables?

My problem is in finding the cut-off point which divide my continuous data into 2 binary outcome. I read articles they used the 75th percentile of the control distribution as cut off point and they ...
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36 views

Power calculations with a continuous independent variable in a case-control study with pair-matched data

So I have been struggling with this matter quite a while now and still have not found a solution to this problem. In fact similar questions have been asked here before but no answer was provided to my ...
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1answer
27 views

Is a comparison of patients between 2 clinics using propensity score matching a matched case control study?

I'm helping my boss design a study that will look at the effects of a clinic level intervention on a patient level outcome. I would like to look at the effect of our intervention on one clinic (...
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32 views

How can we derive Woolf's method?

I tried to derive Woolf's method of estimation using hypothesis with binomial distribution ideas but it was wrong. I cannot send to you what I have done: it is hand writing. So can you tell me how can ...
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29 views

statistical tests for case-control studies on malnutrition

I got some data containing sociodemographic information (e.g. Age, level of education, BMI, type of employment) about mothers of malnourished and well-nourished children. I am trying to design it as a ...
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100 views

Case-Control Likelihood Function Logistic Regression

I'm reading Applied Logistic Regression (2nd Edition) by Hosmer and Lemeshow and I can't follow the derivation given in section 6.3 Case Control Studies, equtions 6.2, 6.3 and 6.4: It is not ...
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43 views

Analysis of matched case-control study w numeric outcome

I might have made a mistake, but here I am with a study where I can't see how the analysis should be done. The setup is fairly straightforward: File 1 with 40 cases A second file with >300 possible ...
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27 views

Sample size determination for various phase

I would like to conduct a PhD research on Certification, Recertification and Implementation of Preschool Vision screening in Malaysia but encountered problems in calculating sample size. From the ...
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1answer
16 views

Can I still call the study placebo controlled if I give the control treatment to the test population as well

I am studying the efficacy of a novel drug in treating a cardiovascular disease with continuous variable results being measured and statistically analyzed. Suppose the control population is getting ...
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32 views

In conditional logistic regression using a mixture model, should main effects be modelled on the same subterm as interactions?

I have a question relating to modelling interactions in a conditional logistic regression model (used for matched case-control study) of the general form $$ R_i = \alpha_{s(i)} e^{\beta_1 z_{1i}} (1+\...
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72 views

How many test cases do I need to be (95%) confident in control group testing when the desired outcome is an increase in revenue?

I am implementing a new pricing structure and am going to be conducting control group testing but am unsure how many test cases I need to be statistically confident in the results. The desired ...
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129 views

Survival probability for a case-control study

I have a case-control study in which 21 patients with a certain clinical outcome and 20 patients without that clinical outcome were (retrospectively) selected from a larger group of patients who were ...
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23 views

Matching and study design

I am currently designing a retrospective case-control study and am having some difficulty coming up with an adequate matching solution. The study assesses a specific surgical procedure and the only ...
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1answer
77 views

Analysing a genotypic 2X2 table instead of a 3X2 table

This could be a simple question to seasoned statistical genetics folks. I have delved into this doing an analysis for a friend on the sideline of a bioinformatics task I was helping her with. An ...
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2answers
41 views

Test Control. A longitudinal study

I have two samples of the same size, one being the 'treated' group, and the other used as a 'control' group. Each group have a different univariate variable (stress level), repeatedly observed over ...
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1answer
179 views

Treatment and Control group, the sample size

I am doing the evaluation for a program with 200 members (they enrolled in the program at different times in the past year and the program doesn't end). Only 78 completed the pre test survey. Now I ...
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21 views

Estimating counts (case number) by logistic regression model

The work we are actually facing is estimating case number of a particular health condition. The classification of the case status (Yes or Not) requires at least one positive lab test result and one ...
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1answer
448 views

Case-control Matched Clustering in Generalized Estimation Equation (GEE) (R:geeglm)

Question: I have matched case-control data and I would like to take advantage of that in my GEE analysis. In the standard approach to GEE analysis, we call each subject a cluster and fit subject-...
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27 views

Do I cluster SEs when the cluster variable is related to the DV?

As part of a case-control study, I am using a logistic regression model to predict whether or not youth were in high school or a detention facility. Data were acquired at one time point, in a select ...
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19 views

Power of a case control test as a function of P(X=1) & P(Y=1)

For our course in statistics we had to build a simulation which would give insight in the power of a case-control study vs that of a cohort study, both trying to discover an association between 2 ...
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51 views

Simulating Case-Control-Covariate Data

I generate data with a covariate $Y_1$ and disease liability $Y_2$ using the following model: $\begin{pmatrix}Y_1\\Y_2\end{pmatrix} \sim \mathcal{N}\left( \begin{pmatrix}\mathbf{X}\beta_1\\\mathbf{X}\...
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164 views

Nonlinear form of ANCOVA?

I would like to compare a control group against a test group using something like ANCOVA. However, the covariates are not simple, as some items may have already been increasing with time, others ...
3
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1answer
374 views

intercept bias in logistic case-control regression: which is the reason?

I don't understand the reason why if I use case-control sampling in a logistic regression then the intercept is biased. The book Agresti 2007 (An introduction to categorical data analysis) says: ".....
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1answer
61 views

reference case-control sampling

I have to use a case-control sampling design to apply logistic regression. I'm looking for a reference that explains which are the advantages and disadvantages of using a high case-control ratio ...
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30 views

Join data sets from retrospective studies

I'm doing the analysis for a study where we need to assess the effect of surgery A (hand surgery) on condition B (trigger digit), adjusting for confounders via logistic regression. The problem is ...
2
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1answer
53 views

What is the definition of “population” in Case-Control Study?

Why in case-control studies, cases and non-case are taken from "Two-different Population?" Why don't they come from a single population?
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45 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?
2
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1answer
306 views

Case-crossover method with conditional logistic regression for poisson model generated data

I would like to run a semi-symmetric bi-directional case-crossover method on some generated data using conditional logistic regression. I generated data from Poisson distribution Poiss(lambda) with ...
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50 views

How to handle data with double the number of cases than controls?

I have genetic SNP data with 50 controls and 120 cases. I am said that comparing few controls with more number of cases will cause spurious associations. The analysis that I want to do is just a ...
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2answers
638 views

How to make the rare events corrections described in King and Zheng (2001)?

I have a dataset with a binary (survival) response variable and 3 explanatory variables (A = 3 levels, B = 3 levels, ...
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1answer
298 views

In a matched case-control study, what do I use for hypothesis testing in the descriptive statistics or the “univariate” associations?

I am doing a case-control study with 80 disease cases matched 1:3 to non-diseased controls and examining whether they had a binary exposure prior to developing the disease. I am using multivariable ...
2
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0answers
64 views

Retrospective Case Study

I am carrying out some research and am a novice to statistics, having done a 2 week module primarily focusing on parametric data and experimental design. However, for my research I am doing a ...
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1answer
23 views

sampling question

I have a question about inclusion criteria to obtain a representative sample of people with "sustained" or uncontrolled high BP. A colleague proposed that I look at health history data retrospectively ...