# Questions tagged [relative-risk]

The relative risk (also called 'risk ratio') is the quotient of the probabilities of an event under two conditions (ie, p1/p2). The RR has a possible range of [0, +infinity). It is a common measure of effect size in biomedical research.

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22 views

### Calculating Risk Ratio: different results with different R-packages (epitools and epiR)

if someone could educate me on how R functions calculate risk ratios I would be grateful. I'm having trouble interpreting results from different packages: epitools ...
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### Population Attributable Fraction from Adjusted Risk/Rate Ratio

Assuming that there are two level of exposure and the outcome of interest is death, the PAF can be estimated following the formula as outlined here https://www.who.int/quantifying_ehimpacts/faqs/en/ ...
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### Are the confidence intervals and p-value for this risk consistent? [duplicate]

I'm trying to calculate a risk ratio with the following 2x2 contingency table, where the rows are exposure groups and the columns are disease status. The first row of the matrix shows that 1/38 ...
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### Does odd ratio make any sense when risk ration can't be computed?

Guides and reviews often explain that odd ratio is preferable to risk ratio when risk ratio cannot be computed. See for example this paper by Ranganathan et al. (2015): Calculation of risk requires ...
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### Can you find the confidence interval with just percentages?

If you are given two relative risks, and you use them to find odds and odds ratio, however you are not given any numerical values. You are just given the risks, why is it not appropriate to create a ...
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### Relative risk not making sense for meta-analysis

I am doing a meta-analysis and struggling with the relative risk values. Looking at the forest plot and the RR for some relative risks I can tell it is incorrect. i.e first study rr should be 0.33. I ...
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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 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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### Reporting significance values for relative risk (RR) and number needed to treat (NNT)

I have calculated the relative risk & number needed to treat using the log-binomial regression model. NNT is calculated as the reciprocal of the marginal difference. Does it make sense to report ...
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### Why I estimate huge RR?

I am trying to do an excercise about temperature related mortality. I want to plot exposure-response curve, identify the temperature threshold and estimate Relative Risk of mortlaity above this ...
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### Analyzing contingencies with levels

Suppose I have a sample with diagnostic information for two diseases, A and B, per individual. If I want to know whether an individual with disease A is more likely to have disease B than an ...
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### How do I calculate effect sizes from Relative Risk, Hazard Ratio, Odds Ratio and regression beta?

I am trying to consolidate data from studies that examine the effects of different risk factors (such as blood pressure, cholesterol) on the development or progression of kidney disease. The papers I ...
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### A regression model for ratio of two Binomial success probabilities

There are two series of observations of two Binomial trials. Observation $i$ of series 1 includes $n_{1i}$, the number of Bernoulli draws and $\overline{p}_{1i}$, the ratio between number of success ...
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### how do i calculate a population size weighted risk ratio?

I am a bit stuck. I have age startified risk ratios from published data from which i have sampled 10,000 iterations. I have a population census data of the population that i am going to apply the ...
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### How do you calculate a paired risk ratio and its confidence interval?

I have some data showing the number of times individuals make GP appointments at the week and at the weekend, over a period of about 5 years. The data also show the number of times each individual ...
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### Identifying risk factors in a study

I have a dataset of patients who have been inpatients (admitted to hospital) and not admitted (but visited as outpatients). Class proportion is 66:34. I have collected a list of features for all ...
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### Posterior of risk ratio as ratio of samples from posteriors of risks

I want to sample from the posterior distribution of a risk ratio. My idea is: define the posterior of risks $R_A$ and $R_B$) for two subgroups (e.g, exposed and non-exposed) in my data, using Beta(1....
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### How to interpret the conclusion for systematic review when the studies had insignificant data?

I am in the process of writing my systematic review in which I asses the longitudinal association between baseline endothelial function and diabetes type II at follow up in healthy participants. we ...
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### What's “the clinically important absolute scale”?

In this article, the authors used the sentence "...risk difference (i.e., treatment effect on the clinically important absolute scale)". What did they mean by "clinically important ...
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### What's the interpretation of the ratio of the odds ratio between the experimental and the control arm?

Table 1 of this article show the associations between the outcome and variables, the authors presented the OR_ctr in control arm and ...
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### Conditions when the log of Relative Risk is approximately Normal

Under what conditions is the log of RR (or OR) approximately Normally distributed? Sources would be very much appreciated - wikipedia for example just states the SE formula but provides no information ...
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### Vertical translation of independent variable vs OR and independent variable vs RR curve

i have been trying to predict risk of developing a cancer from genetic data. At the end I plotted a curve, that shows odds ratio (OR) and relative risk (RR) as a function of polygenic risk score (PRS) ...
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### What is the relationship between the risk ratio and the weight of evidence? [duplicate]

I've been reading about risk ratios as typical measures in clinical settings. In the finance and credit literature, there is the weight of evidence (WoE) measure that is used to encode and study ...
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### How to calculate risk ratio for chemical substances

Simple example: Three different chemical substances are given to patients (each to 5 patients). Some patients die, some not. Samples (number of patients) are not equal. How to calculate the rate of ...
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### risk-ratio confidence-interval - but weighted?

I have survey data, with weights that adjust the sample to be nationally representative, from two time points. There is a binary presence/absence variable. Presence increases from time 1 to time 2. I ...
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### metafor for incidence rates - how to calculate relative risks and 95% CI's

I'm very new to the metafor package and wanted to check my interpretation of the model output, specifically in regards to calculating relative risks and confidence intervals. I've used the rma.mv() ...
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### Interpreting the magnitude of the relative risk

I am used to interpreting Cohen's d in terms of small/medium/large effect sizes (cf. Cohen 1988 or Sawilowsky 2009) where, for example, a a Cohen's d of 0.2 corresponds to a small effect size. I am ...
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### Multiple risk ratio analysis or single multiple logistic regression for survey

I was asked by a doctoral student to analyze the answers to an old questionnaire her lab has and would like to publish the results of. There are a few questions with regards to animal care and disease ...
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### Assess temporary effect of treatment

Imagine that I have a treatment that reduces the likelihood of response to a stimulus. This could be anything you like, but the simplest example is of a treatment (e.g., hand washing, mask wearing, ...
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### What does the decomposition of a relative risk look like?

Say I have a relative risk of smokers that smoked 1-20 cigarettes per day. What is the mathematical identity between that RR, the RR of those that smoked 1-10 cig/day, and RR of those that smoked 11-...
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### Why is information gain rarely used as a reported effect size?

Commonly, in reporting effect sizes in medical articles, papers typically report: risk difference (RD), relative risk (RR) and odds ratio (OR) (and for variable timescale cases and other situations, ...
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### Odds Ratio Vs. Risk Ratio

Relative risk, odds ratio, risk ratio, risk difference - these are all measures of the direction and the strength of the association between two categorical variables. Can I use any of these four ...
107 views

### Define statistical potential energy [closed]

I am looking for a statistical method that closely relates to the idea of potential energy. Here is a quick google definition for potential energy "...the energy possessed by a body by virtue of ...
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### how to map an estimated risk ratio of 0.76 to increased life expectancy

Andrew Gelman's blog contains the following question: John Ioannidis writes: Assuming the meta-analyzed evidence from cohort studies represents life span–long causal associations, for a baseline ...
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### Get relative risk ratio and confidence interval from logistic regression [duplicate]

There are many examples on these forums of people calculating risk ratios from logistic regressions, but none of them seem to match my situation. I have two predictor variables - one continuous and ...
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### Likelihood-Based Confidence Intervals for ratio of risk ratios

Ratio of Risk Ratio (RRR), along with Relative Excess Risk Due to Interaction (RERI), has been used to quantify the joint effects of 2 exposures in epidemiology. Quoting Joshua N. Pritikin CIs ...
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### Relative risk per increment

I have a study that reports summary RR and RR using an increment (e.g., 100 grams per day). In layman's terms, what does the RR using an increment mean? For example, eating chocolate overall has a RR ...
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### Odds ratio and Risk ratio disagree?

Is it possible for the odds ratio and the risk ratio for a variable to disagree? For example - an odds ratio >1 and risk ratio <1?
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### Math formula to reproduce a plot comparing Relative Risk to Odds Ratios

I'm trying to reproduce Figures 1, 2 and 3 in this paper (notice that clicking on the FIGURES/TABLES tab is enough to see the plots - no need to sign up or create an account), simply to understand how ...
2k views

### Why is odds ratio an estimate of relative risk?

This link says In epidemiological terms, the odds ratio is used as a point estimate of the relative risk in retrospective studies. I understand that odds ratio is calculated in case control ...
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### Converting Cohen's d to a Relative Risk for a model-based economic evaluation

Hello researchers: my question is about the use of forest plot results for an economic model. In a forest plot you could have the following results: 0.34 [0.22, 0.45], which would be the pooled ...
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### Summary RR to % risk increase?

In a comprehensive meta-analysis the 'summary RR per 120 g/day increase in red meat intake was 1.20 (95% CI 1.04–1.38)' In a review citing this information, they have written rather 'a 20% increase in ...
398 views

### What does a large Relative Risk Ratio mean?

I run a multinomial logistic regression model on a dependent variable Y with five levels (with one of them set as a reference). Though the outputs of the model were in line with my expectations, I ...
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### Is there a two-by-two contingency table dataset where an Odds Ratio estimate would work and a Risk Ratio would fail?

I am wondering if there is an example of a two-by-two contingency table dataset where an Odds Ratio estimate would work and a Risk Ratio would fail, or vice versa? In additional are there cases where ...
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### How would I conduct a relative risk meta-analysis, when the exposure levels in the data are presented in overlapping ranges?

For example, if I have studies observing the dose-response relationship between alcohol (g/day) and breast cancer, and the exposures are reported as heterogeneous and overlapping ranges (10-20g, 15-...
1k views

### Odds ratios are inappropriate for a cross-sectional or cohort study

I'm aware of the issues regarding the use of relative risk in a case control study. But a colleague recently told me that odds ratios are inappropriate for cross-sectional and cohort studies but can't ...
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### Odds ratio and relative risk

I'm trying to understand how the odds ratio can approximate the relative risk under the rare disease assumption. I'm given the relative risk for disease $B$ and risk factor $A$ is 2 and that 20% of ...
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### How to calculate relative risk if the reference group has an incidence of 0?

this appears to be a quite difficult question. As we know, if 20% of the smokers developed lung cancer and 10% of the non-smokers developed lung cancer, then we say that cigarette smoking is ...
212 views

### Interpreting 95% confidence intervals for relative risk (known true RR, 100 samples)

Let's assume that we are investigating how tobacco smoking is associated with incident lung cancer in a population. In the full population, the true relative risk of lung cancer associated with ...