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

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energy adjusted nutrient intake

I have a data on 7 nutrients (intake of 150 people - 75 men and 75 women). Can i do factor analysis to derive the nutrient intake pattern? If so shouldn't each nutrient be adjusted with the total ...
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How to convert epidemiological Relative Risks (RR) to carcinogenic Inhalation Unit Risk Factor (IUR)?

Measures of effect in epidemiological studies on air pollution are normally presented as Relative Risk (RR). Classical Risk Assessment procedures (e.g. US-EPA) require instead a Inhalation Unit Risk ...
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143 views

Statistical method for modelling of disease incidence for NGO

I am trying to provide help to an NGO in the non-profit sector that is running a disease screening program: The program visits thousands of villages a year. A village has a population (on average ...
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44 views

Estimating an overall summary statistic (mean) for a value reported by ten published studies

Background I am writing a systematic review and meta-analysis of the association of exposure to X with the outcome Y. I have identified ten studies that report on this subject. This will be a ...
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1answer
98 views

Why no mention of penalized regression techniques in Applied Logistic Regression, 3rd edition, by Hosmer, Lemeshow, and Sturdivant?

Just ordered this textbook, and Wow, the complete omission of this subject from an otherwise excellent reference on logistic regression is a bit surprising. The 2nd edition was published in 2000 - ...
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55 views

How to gently introduce epidemiologists/public health coworkers to advanced predictive modeling?

Coming from a social science and epidemiology background, my coworkers were trained on least squares regression, logistic regression, and survival analysis. They like to see 95% confidence intervals ...
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16 views

Relationship between “attributable risk percentage” and “relative risk”

I refer to the text provided from http://www.healthknowledge.org.uk/public-health-textbook/research-methods/1a-epidemiology/numerators-denominators-populations below: Relative Risk "Relative ...
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12 views

Using AIC to select an upper bin for a counting variable

I have some patient data and I'm using a logistic model to explore factors that might affect a patient considered severe/not severe for a disease (the DV). Many of the variables are counts; counts ...
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14 views

Pearson r with percentages across time

Data sources: CDC National Survey of Family Growth, CDC vital stats. Population: American women aged 15-44 in 1982, 95, 2002, 2006 Sample sizes: several thousand Can I use Pearson r to show linear ...
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29 views

design and analysis of experiments

Kindly recommend some teaching material for "design and analysis of experiments" for the students of biostatistics and epidemiolody. Pls note that the students have only little knowledge on ...
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45 views

Epidemiology cohort studies question

If we are conducting a cohort study of factors associated with recurrent myocardial infarctions (MI) following the first one, should our study population at baseline include subjects who had ...
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10 views

How do you do a power calculation for a 2-phase prevalence survey?

I'm trying to work out what sample size I need to calculate a prevalence rate within certain confidence intervals, using a two-phase design. There is a screener test. Everyone that screens positive ...
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10 views

Tests behind comparison of a sample's survival to that of the general population

In the literature there are often reports of comparisons of a sample's survival to that of the general population. Life and mortality tables are cited however the tests and statistical procedures ...
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34 views

What does “units” mean in epiR package?

From epiR manual for epi.2by2 function: units: multiplier for prevalence and incidence estimates. In examples it is set to 100, units=100. What does it mean? ...
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2answers
57 views

Prognostic factor vs. risk factor

As far i understand the difference between Risk factor and Prognostic factor is : Risk factor is the ...
110
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8answers
26k views

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 ...
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27 views

Optimal way to match cases and controls w/ multiple per strata

I need to do a matched analysis. However, I cannot find good reference for the best way of matching when each stratum may contain multiple cases and controls. As an extreme example, say we want to ...
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1answer
307 views

Making a cumulative incidence plot in R

Background I have a survival object in R called km. ...
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1answer
71 views

Purposeful selection and confounding

I conducted purposeful selection as outlined in Jewell's Statistics for Epidemiology. The log likelihood tests showed covariates, which I considered to be confounding though not significant in the ...
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1answer
96 views

penalized regression applications in epidemiology

I am seeking advice on penalized regression models for selecting covariates in epidemiological studies. A difficult tasks I face is feature selection while still attempting to account for confounding ...
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21 views

Weights for retrospective cohort data

Suppose you randomly identify individuals with a certain disease (cases) at time $T$, then you identify a sample of individuals without disease at time $T$ (but at risk for disease) in a population of ...
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1answer
50 views

Separating effects of foods and of food components in nutritional epidemiology

I have data on average long-term intake of common foods of a medium/large cohort (n=500+). It was assessed semi-quantitatively (that is, interval-censored). From these about 100 food items and their ...
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257 views

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 ...
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2answers
189 views

Absolute risk and prevalence?

From Wikipedia If the absolute risk in the control group is available, conversion between the two is calculated by: $$ RR \approx \frac{OR}{1 - R_C + (R_C \times OR)}$$ where: RR = ...
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117 views

What is the difference between period prevalence and incidence rate?

I am confused about the difference between period prevalence and incidence rate. Following are from Wikipedia: The incidence rate is the number of new cases per population in a given time ...
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206 views

Comparing multiple incidence rates

I asked the following question on stack overflow yesterday: Negative binomial function in R Reading comment 2, I understand that I cannot use a negative binomial modeling approach (a Poisson model ...
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3answers
170 views

Basic epidemiological models in R

To support an education project around neglected infectious diseases in Sub-Saharan Africa, I aim to estimate and report some very basic epidemiological models in R to build intuition and ...
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Is there a word for the phenomenon that the old are generally less affected by risk factors?

In epidemiology, this occurs often: Old people are less prone to the influence of risk factors. For example, the Framingham risk score, which tries to estimate cardiovascular risk, gives 8 or 9 points ...
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How to best account for population sizes in disease outbreaks

Say one has the fatality and survivor rates of a pathogen in terms of geographical location (e.g., the latest data on the MERS-CoV). ...
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42 views

Terminology to Use

Should you say a factor is associated with a disease or disease risk? For example, which is better to say: Smoking is associated with lung cancer Smoking is associated with lung cancer risk
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273 views

Are studies in epidemiology all observational?

Are studies in epidemiology all observational and not controlled? My impression comes from Wikipedia, which lists: Case Series Case Control Studies Cohort Studies Outbreak Investigations and no ...
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70 views

What type of study is this?

Suppose someone is trying to estimate the diagnostic prevalence of ADHD in a cohort of individuals born in 1985. What type of study is this? This is not a prospective cohort study because we are not ...
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112 views

What would be a suitable way to present a prevalence rate?

Suppose we say that the prevalence rate of some disease is $1$ in $50$. Does this make sense? Or should be convert this into a $ \%$? That is, should we say that the prevalence rate is $2 \%$?
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2k views

What is the definition of “source population”?

What is the definition of source population? Suppose we screen $100,000$ people and then include $50,000$ people in three studies $A$, $B$ and $C$. For study $A$, is the source population the ...
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3answers
530 views

How to interpret odds ratio?

Suppose we have a baseline exposure group and 2 other exposure groups for a case control study. Suppose the odds ratio for the first exposure is $1.5$ and the odds ratio for the second exposure is ...
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44 views

Confounding variables

Suppose we want to study the association between alcohol consumption and cancer. If we include people who also smoke (a confounder), would this lower the relative risk of cancer for alcohol drinkers? ...
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70 views

Can GEE handle small unaccounted clusters in data?

A survey is being administered in a resource intensive setting. A 2-phase study design will be implemented using cases and controls identified by a certain behavior (say, smoking) and they will be ...
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473 views

How do I calculate whether something is an independent risk factor?

I do not know what calculation/formula to use to show that something is an independent risk factor. E.g., in a cohort study: Group A (n=1000) - exposure to X - outcome exposed 70/1000 demonstrate Z ...
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110 views

Computing event rates given RR + CI and total sample size in each treatment group

I am looking at some data for the risk of mortality in patients undergoing treatment A vs treatment B and I am given the total number of patients in each treatment arm and the relative risk + ...
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1answer
85 views

Conditional fixed effects Poisson *with population exposure*

Reading a paper, the authors use a "Conditional fixed effects Poisson with population exposure." I wasn't sure what "population exposure" meant, so I looked it up. It seems like the term comes from ...
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104 views

Ways to Estimate Date of Conception

Why don't epidemiologists ask people when they had sex? Why do they estimate time of conception from the birth date? This seems to introduce unnecessary error. Wouldn't it be better to record the time ...
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204 views

Calculating confidence intervals for prevalence differences

I would like to calculate the confidence intervals for prevalence differences. If I have the CIs for the prevalence, can I simply subtract the upper limit of one Ci from the upper limit of the other, ...
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1answer
74 views

Simulation of woman's age of getting breast cancer (cumulative incidence rate)

I am writing a programme to simulate the age at which women will get breast cancer. I have data on the cumulative incidence rate for the whole population. What I am doing right now is using Monte ...
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2answers
79 views

Is it fair to say that most epidemiological studies are observational?

Is it fair to say that observational studies are the 'bread and butter' of epidemiological studies? By epidemiological studies I mean studies looking for an association between an environmental ...
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1answer
414 views

Collapsibility: Odds Ratios versus Risk Ratios

It is known that odds ratios enjoy a certain symmetry. For example, the odds ratio of outcome $Y$ is the inverse of the odds ratio of outcome $\neg Y$. Risk ratios, on the other hand, do not enjoy ...
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182 views

Incidence density

Suppose there are $6$ people in a population. During $2$ weeks $3$ people get the flu. Cases of the flu last $2$ days. Also people will get the flu only once during this period. What is the incidence ...
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1answer
1k views

Power calculations, logistic regression with continuous exposure--cohort

I'm trying to estimate power in a logistic regression with a continuous exposure in a cohort study (ie, the ratio of the sampling probabilities is 1). I have population cumulative incidence ...
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199 views

Estimator for an incidence rate

While going through a statistics course for medicine students, I ran accross a problem related to incidence rates. The context of the problem is a chapter about the Poisson distribution. In the ...
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69 views

Dealing with dependant data when estimating probability of an event happening

I have 10 years worth of data from 1970 to 1980 (40 quarters). For each quarter I have five measurements M1, M2, M3, M4 and M5. TWIST: Although the data I have is on individual patient level, the ...
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What should this poor guy be told? [duplicate]

Possible Duplicate: What are the chances my wife has lupus? A day or two ago a man posted a question on math.stackexchenge about whether his wife likely has lupus, given the diagnosis. ...