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7 votes
Accepted

Calculation of the Confidence Interval for Incidence Rate Ratio using Exact Approach

The authors of this study apparently carried out both univariate and multivariate stratified Cox proportional hazards models. They report hazard ratios with their 95% CI from the observed results (see ...
chl's user avatar
  • 54k
5 votes

Calculate probability of disease appearance

I personally feel this lends itself well to a survival analysis. You have people without moles in a certain hand at the start of the period (your at risk population); you can select these, and you ...
James's user avatar
  • 473
4 votes

How to calculate 95% CI for cumulative incidence rate using R?

This sounds like an incidence rate not cumulative incidence, which is a risk (number of cases divided by original disease-free population). Presumably the 95% CI for cumulative incidence is the same ...
James Kirkbride's user avatar
4 votes

Comparing two groups of incidence rates

If you want to compute a causal effect you need to control for confounders. The problem is, that you really need to find all confounders, otherwise your results are not reliable, and in the worst case ...
frank's user avatar
  • 10.9k
4 votes

Interpretation of incidence rate ratio

3,300 is wrong because you've simply multiplied the N of 10,000 by 1-IRR of to obtain 3,300. This would only be correct if everybody in the placebo arm was expected had Rota GE at least once by 60 ...
AdamO's user avatar
  • 63.3k
3 votes

How to calculate 95% CI for cumulative incidence rate using R?

Use a Poisson GLM to do maximum likelihood under the assumption of independent interarrival times: ...
AdamO's user avatar
  • 63.3k
3 votes

Calculate incidence rate per person or in total

It's a simple rule that the sum of ratios is not the same as the ratio of sums. This is a result of Jensen's inequality. To really compare apples and oranges, you need to "average" out the second ...
AdamO's user avatar
  • 63.3k
3 votes

what is x per 100 person years mean?

Let's assume you followed 100 people. 50 of them you followed for 2 years and nothing happened. 25 newly developed the disease of interest after being observed for on average 1 year (not counting time ...
Björn's user avatar
  • 33.2k
3 votes
Accepted

Incident rate ratios with log-transformed variables in Poisson regression

It seems this didn't generate any interest, so I'll answer with what I've found after a few weeks. IRRs are multiplicative, so: 'holding all other parameters constant, the change in ...
Mainard's user avatar
  • 400
3 votes
Accepted

Can odds ratio be in different direction to rate ratio?

You and the article are just looking at reciprocal ratios. $$(9/7129)/(795/306096) = 0.49$$ $$ (795/306096)/(9/7129) = 2.06$$
ampanmdagaba's user avatar
3 votes
Accepted

Incidence rates from manual calculation differs from that obtained from the estimated marginal means of a poisson regression

You are right that in this particular case the two approaches should give the exact same results (with some possible small differences in the confidence intervals). You had the wrong formula for the ...
Björn's user avatar
  • 33.2k
2 votes

What type of statistical test should be used to compare successes of two treatments?

You have two treatments: drug A (hot) and drug B (cold). The Null- Hypothesis would be that cure rate (or proportions) of A equals to the cure rate of B. Null hypothesis: $p_{A} = p_{B}$ ...
kkk's user avatar
  • 308
2 votes

What type of statistical test should be used to compare successes of two treatments?

This is a basic 2 by 2 frequency table. A chi-square test of independence would be appropriate. Also, you could use a risk ratio or odds ratio to describe the size of the effect and a construct ...
dbwilson's user avatar
  • 1,778
2 votes
Accepted

Relationship between survival time and incidence rate

If all patients have the same constant risk of discharge, then you have exponential distribution of length of stay and average time of stay = 1/incidence rate. Or, to put it differently, if ...
Ott Toomet's user avatar
2 votes

Adjusting variable for covariate to calculate rates or metric

The report goes into their adjustment strategy a little bit, and in general your instincts are correct: when people talk about adjustment, they usually mean they're including those variables in a ...
Fomite's user avatar
  • 23.4k
2 votes

Incident rate ratios with log-transformed variables in Poisson regression

Let's write down the regression equation for your model: $$ \log(E(Y\mid X_1, X_2)) = \beta_0 + \beta_1\log(X_1) + \beta_2\log(X_2).$$ As usual, you can express $\beta_1$ as the difference of $\log(E(...
M Turgeon's user avatar
  • 369
2 votes

Meta-analysis with random effects on prevalence data with > 2 possible outcomes: is it necessary that the weighted prevalences all add up to 100?

When I do this for each group individually, the prevalence values do not add up to 100. Is this to be expected? This is to be expected, but it is IMHO possibly problematic. It indicates you are not ...
Martin Modrák's user avatar
2 votes
Accepted

Network Meta-analysis with poisson regression

Yes, a network meta-analysis is quite general and can be applied to any probability model including Poisson. The underlying assumption is that multiple interventions have been applied to different ...
Geoffrey Johnson's user avatar
2 votes
Accepted

Derivation of confidence interval of incidence rate ratio

Reading up on the background of generalized linear models (glm) may help. The Wikipedia article may help: https://en.wikipedia.org/wiki/Generalized_linear_model Generalized linear models work with ...
Greg Snow's user avatar
  • 52.2k
2 votes
Accepted

Conway-Maxwell-Poisson (CMP) - Coefficient interpretation (Log/IRR)

First off, you are right that family="compois" will by default use a log link as is standard in Poisson regression. You can learn this from the output of <...
Stephan Kolassa's user avatar
2 votes
Accepted

Advantage of Poisson model over Cox PH model for analyzing first event?

This is pretty much the tradeoff between assuming a particular functional form for a relationship, which can be more powerful if it actually holds, versus working with a semi- or non-parametric model ...
EdM's user avatar
  • 94.4k
2 votes

Is there a difference between rate ratios and hazard ratios?

You have to be careful with the time period that is used for evaluating the incidence rate. The Wikipedia page discusses the usual interpretation of "incidence rate": Use of this measure ...
EdM's user avatar
  • 94.4k
2 votes
Accepted

What are the comparative advantages and disadvantages of interpreting regression output using marginal effects vs. ratios?

Let's say I'm running a model to predict getting a job (so the dependent variable is 1 for people who have a job and 0 for those who do not). Let's say that I have one independent variable that I ...
Graham Wright's user avatar
2 votes
Accepted

Survival analysis vs Cumulative incidence vc Incidence rate for cohort with varying baseline dates

This is a competing-risks situation involving right censoring, with disease diagnosis and death as the competing risks. The right censoring makes simple ANOVA inappropriate. In principle there is no ...
EdM's user avatar
  • 94.4k
1 vote
Accepted

What should we report in our manuscript for negative binomial regression, IRR or OR?

I'll assume you have used negative binomial (NB) regression to analyze over-dispersed counts per time unit (e.g. modelling the number of hospitalizations per patient-year of follow-up by having a NB ...
Björn's user avatar
  • 33.2k
1 vote
Accepted

Calculation of 95% Confidence Interval for an Incidence Rate Difference

So a variance estimator for the the incidence rate is $$ \widehat{Var}(\widehat{IR_1}) = \frac{A_1}{T_1^2}$$ where $A$ is the number of events and $T$ is time. A variance estimator for the incidence ...
pzivich's user avatar
  • 2,412
1 vote

Incidence rate ratio after negative binomial results in R

Try this: exp(coef(Mymodel)) Mymodel is a model object containing much more than the fitted coefficients, and some of this ...
kjetil b halvorsen's user avatar
1 vote

Determining the statistical significance of change in incidence rates

Yes there is but you need less aggregated data. You now only have 5 data points which is usually not enough for statistical testing. Could you maybe get the monthly or even daily data? When comparing ...
B. Bram's user avatar
  • 93
1 vote

Cumulative Incidence Rate in R Statistics

Hey @bvowe in terms of your first question, the result is ...
Marcin's user avatar
  • 1,049
1 vote
Accepted

What is the difference between 1-year partial prevalence and annual incidence?

This page from one of your links puts it pretty clearly: Partial prevalence is the number of all cancer patients, being alive at specific date (usually the last day of calendar year) and being ...
EdM's user avatar
  • 94.4k

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