Questions tagged [epidemiology]

Epidemiology is the study of the distribution and spread of disease or illness at the population level.

Epidemiology is the study of the distribution and spread of disease or illness at the population level. Epidemiologists make use of techniques and approaches from numerous fields. Statistical and mathematical models drawn from biostatistics may be used to model or predict disease rates, while social science approaches such as interviewing and survey research might be used to elucidate information on social risk factors for disease. Epidemiology is considered one of the foundational methods employed in the practice of public health.

Drawing distinctions between health services research, epidemiology, and clinical research can be challenging, as these all generally share the same biostatistical foundation and differ only in approach and subject matter. Health services research focuses on the health care system, epidemiology focuses on population-level distributions of disease, and clinical research focuses on specific aspects of clinical care. Questions regarding all three can be placed under this tag, as CrossValidated does not have an HSR or clinical research tag.

Clinical trials - specifically designed trials for new drugs or interventions with strict regulatory guidance and statistical methods - are separate from these fields, and should be put under the clinical-trials tag.

Suggested reading:

http://www.who.int/topics/epidemiology/en/

http://en.wikipedia.org/wiki/Epidemiology

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Is Facebook coming to an end?

Recently, this paper has received a lot of attention (e.g. from WSJ). Basically, the authors conclude that Facebook will lose 80% of its members by 2017. They base their claims on an extrapolation of the SIR model, a compartmental model frequently…
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A chart of daily cases of COVID-19 in a Russian region looks suspiciously level to me - is this so from the statistics viewpoint?

Below is a daily chart of newly-detected COVID infections in Krasnodar Krai, a region of Russia, from April 29 to May 19. The population of the region is 5.5 million people. I read about it and wondered - does this (relatively smooth dynamics of new…
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Understanding regressions - the role of the model

How can a regression model be any use if you don't know the function you are trying to get the parameters for? I saw a piece of research that said that mothers who breast fed their children were less likely to suffer diabetes in later life. The…
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Poisson regression to estimate relative risk for binary outcomes

Brief Summary Why is it more common for logistic regression (with odds ratios) to be used in cohort studies with binary outcomes, as opposed to Poisson regression (with relative risks)? Background Undergraduate and graduate statistics and…
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Which statistical model is being used in the Pfizer study design for vaccine efficacy?

I know there's a similar question here: How to calculate 95% CI of vaccine with 90% efficacy? but it doesn't have an answer, at the moment. Also, my question is different: the other question asks how to compute VE, using functions from a R package.…
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How to cope with exploratory data analysis and data dredging in small-sample studies?

Exploratory data analysis (EDA) often leads to explore other "tracks" that do not necessarily belong to the initial set of hypotheses. I face such a situation in the case of studies with a limited sample size and a lot of data gathered through…
chl
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How much lung cancer is really caused by smoking?

On tobacco products one can often see the statistic that nine out of ten lung cancers are caused by smoking but is this number accurate? I am sceptical about this stat for two reasons. Firstly, if you compare cigarette consumption rates over time…
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What statistical model or algorithm could be used to solve the John Snow Cholera problem?

I'm interested in learning how to develop a geographic approximation of some kind of epicenter based on the data from the John Snow Cholera outbreak. What statistical modeling could be used to solve such a problem without prior knowledge of where…
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Time series for count data, with counts < 20

I recently started working for a tuberculosis clinic. We meet periodically to discuss the number of TB cases we're currently treating, the number of tests administered, etc. I'd like to start modeling these counts so that we're not just guessing…
Matt Parker
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Adjusting for covariates in ROC curve analysis

This question is about estimating cut-off scores on a multi-dimensional screening questionnaire to predict a binary endpoint, in the presence of correlated scales. I was asked about the interest of controlling for associated subscores when devising…
chl
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Can data cleaning worsen the results of statistical analysis?

An increase in the number of cases and deaths occurs during epidemics (sudden increase in numbers) due to a virus circulation (like West Nile Virus in USA in 2002) or decreasing resistance of people or contamination of food or water or increase in…
DrWho
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Explain model adjustment, in plain English

Reading about methods and results of statistical analysis, especially in epidemiology, I very often hear about adjustment or controlling of the models. How would you explain, to a non-statistician, the purpose of that? How do you interpret your…
radek
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COVID in Germany, LOO-CV for time series

The paper in Science [1] infers change points in COVID spread in Germany. The authors fit the number of daily cases assuming one (red), two (orange), and three (green) change points. Every change point adds two parameters to the model. It is hard…
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What are the case studies in public health policy research where unreliable/confounded/invalid studies or models were misused?

I am drafting a literature review on a current public health issue where data are confounded: What are common historical case-studies that are used in public health/epidemiology education where invalid or confounded relationships or inferences were…
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What is the difference between effectiveness and efficacy in determining the benefit of therapy 'A' on condition 'B'?

The context of this question is within a health framework i.e. looking at one or more therapies in the treatment of a condition. It appears that even well respected researchers confuse the terms efficacy and effectiveness, using the terms…
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