Questions tagged [prevalence]

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Prevalence / Incidence and Relative Risk

I'm doing a course in biostatistics and I came across this question to solve: "Consider a two-year follow-up study of the association between a measure of stress (dichotomised into two levels: ...
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Appropriate statistical test evaluating difference in proportions between two groups over multiple time points

Over the course of a year, I took samples from dogs and their beds and looked for the type of bacteria in the bed and in the dog every month. I did not get samples from the same dogs or the same beds ...
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How should the prevalence be calculated when determining prevalence-adjusted PPV?

I am assessing the performance of a test for a certain disease. I have selected the disease cases and controls from a large dataset that is reasonably representative of the general population. As I ...
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How to relate prevalence to factors with multivariate analyses model (GAM beta inflated)?

While analizing the prevalence of cows to brucellosis (illness), and in order to relate it to a set of factors like country, state, and detection technique, I need to apply a multivariate analysis ...
Adonis Cedeño's user avatar
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Adjust a crude rate based on observed prevalence within population [closed]

I have data such as the below: Area Admissions Population Crude rate per 100,000 Cambridge 137,204 1,077,382 12,735 London 111,896 1,013,985 11,035 I have been asked to 'adjust the crude rate for ...
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Calculating prevalence and incidence based on a given rate

I apologize for the poorly worded title, but I have a Prevalence/incidence question that got me confused Hello all, I just came out of my epidemiology exam, and there’s this question that’s bothering ...
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Calculating prevalence and incidence from a given rate

I apologize for the poorly worded title, but I have a Prevalence/incidence question that got me confused Hello all, I just came out of my epidemiology exam, and there’s this question that’s bothering ...
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Continuous variables and prevalence ratios interpretation

If I were to estimate a poisson regression model with robust variance (or a logbin or cox regression model) to obtain prevalence ratios, could I interpret a continuous variable predictor? So for ...
StatsAreHard's user avatar
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Age Adjusted Prevalence at region level with only country-level population distribution

I'm trying to calculate age-adjusted prevalence for a bunch of different chronic diseases from hospital data in a specific area and I'm having some difficulty. I have total country level population, ...
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False positive correction categorical data

I am trying to understand how to correct for chance categorisation as either impaired/not impaired across a range of measures. Briefly, I am looking to summarise prevalence statistics across ~40 ...
acerhelia's user avatar
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Accounting for overrepresentation of positives in binary classification test set for calculation of precision and recall

I have a binary classification task with highly imbalanced data, since the class to be detected (in the following referred to as the positives) is very rare. For data limitation reasons my test set ...
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Calculating the confidence interval or standard error of a PPV adjusted for prevalence

I am trying to evaluate how well a disease test performs in a case-control study. In this example, the prevalence is 0.5%, and the results are below: Disease + Disease - Test + 40 (TP) 10 (FP) Test ...
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What is the probability of at least one person in a sample of k people being infected?

Given the prevalence, sensitivity and specificity of a single test are known.
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Infection rate time-series analysis

We have some surveillance data from a hospital that include infections with antibiotic-resistant bacteria and the number of admissions, patient-days so that I can calculate incidence and prevalence. ...
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1 answer
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How to estimate disease prevalence using logistic regression when some people are measured several times

I have a binary variable indicating the presence or absence of a disease as well as variables for time and other covariates. SOME (not all) people are observed (tested) several times. Suppose I want ...
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How to deal with ragged power curve

I am exploring various methods for sample size calculation and power analysis from binomial data, and frequently coming up against ragged power curves that go up and down as sample size increases. I ...
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2 answers
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Why exactly does a classifier need the same prevalence in the train and test sets?

Here are some commonly seen statements about the importance of prevalence in the train and test sets when developing a classifier: "Another reason not to rebalance datasets is that models should ...
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The percentile method

a research used the percentile method to find the prevalence in severe group as below: The outcome variable was categorized using percentiles to Mild, Moderate, and Severe in the Symptom Severity ...
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Post test probability with a ROC curve

I have data that is normally distributed related to risk of a particular disease. At the median of the distribution, you would expect to observe the population prevalence level of disease P0=0.01. For ...
sethsh7's user avatar
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1 answer
117 views

Should you include time as a continuous predictor when estimating incidence or prevalence?

Suppose one has a time series of disease counts and populations (at risk, total etc.) or, equivalently, binary events of disease status. Then suppose one wanted to present estimates of incidence or ...
user167591's user avatar
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How do i perform a meta-analysis of prevalence rates using metafor package (with no treatment group)? [closed]

I have a spreadsheet with this type of information: ...
Wellydo Escarião's user avatar
3 votes
1 answer
127 views

When comparing classifiers on different datasets with different prevalences, is it valid to calculate prevalence-adjusted PPV?

Scenario: comparison of 2 different binary classifiers Both classifiers report sensitivity and specificity and number actually positive (P), but classifier 1 is tested on a dataset with prevalence 20%,...
sideburns28's user avatar
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1 answer
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prevalence ratio question

I understand that prevalence ratio is ...
Science11's user avatar
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How to calculate NNT when it's NOT a clinical trial?

I am working on a revise and resubmit for a journal article. This is an observational, cross-sectional study. We compared endorsements of different behaviors across groups (e.g., 30.1% of Group 1 ...
Blair Burnette's user avatar
1 vote
1 answer
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Prevalence/proportion estimates: sampling/screening steps in different order make a difference for SE of the estimate?

We have a question that is quite puzzling but that will surely be something others have come across (e.g., in epidemiology). There are two methods we are thinking of to get a prevalence estimate, the ...
Anna Van 't Veer's user avatar
1 vote
1 answer
254 views

How to treat proportions with different sample sizes as response variable in GLM / GLMM?

For an ecological research project, I am trying to model the effect of different factors on the prevalence of a specific pathogen in ticks. Ticks were collected from around 80 different plots and ...
claritali's user avatar
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Testing the difference between 2 prevalence ratios

I want to test if prevalence ratio (a disease in Men vs Women) in population A is statistically different from population B. I wonder what statistical test can be used?
Loh's user avatar
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Is there criteria on when to choose ODDS ratio or Prevalence Ratio?

Am stack between using Prevalence Ratio and ODDS Ratio. Is there any statistical backing on choosing one over the other? If yes, what could that be and would one generate the PR in R?
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Compare geographical distributions of prevalences

I would like to ask you what statistical method should be used to compare two prevalence distributions. My problem is the following: I have two prevalences of two diseases A and B (non-exclusive) per ...
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7 votes
3 answers
1k views

Are thresholds for logistic regression models prevalence-specific?

I wonder if thresholds for logistic regression models are prevalence-specific. I assume that they are, however, I am not sure about the basic statistical principles behind it and how to deal with the ...
ava's user avatar
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2 votes
1 answer
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Is there any form or program that generates prevalence ratio values ​through logistic regression?

When performing a binomial or multinomial logistic regression, odds ratio (OR) values ​​are generated. Is there any form or program that generates a prevalence ratio value instead of OR?
Anderson N. Barbosa's user avatar
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2 answers
26 views

Why do we measure incidence, if we can measure the prevalence of a disease for two successive years instead?

Why do we measure incidence, if we can measure the prevalence of a disease for two successive years and then subtract the latter year's figure from the former years number and find out the incidence? ...
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How to estimate prevalence with a zero incidence (rare disease)? [duplicate]

I had to solve the following problem. Newborn screening has been implemented for a very rare pathology. For 6 months, and out of 50,000 births observed, no sick case was observed. What is the ...
Flora Grappelli's user avatar
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1 answer
63 views

How does a small sample size (underpowered study) affect the prevalence?

I am doing a meta-analysis where I calculate an overall prevalence value for multiple studies. I have submitted my manuscript to a journal. I used sample size as one of the risk of bias criteria, ...
aspire94's user avatar
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2 votes
2 answers
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Question concerning Covid infection data reported by the media

I tried searching StackExchange for existing posts about this, but I could not find them. Please redirect me if appropriate. My question is very simple, and perhaps partly related to the observations ...
user6376297's user avatar
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0 answers
197 views

Prevalence threshold calculations error

I see on this page the formula for calculation of prevalence threshold: Given also are following values on that page: ...
rnso's user avatar
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3 votes
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215 views

Correction for sample overlap in a meta-analysis of prevalence (metafor package)

I want to conduct a meta-analysis of around 30 studies (from a systematic review). Some background of the studies: The quantity of interest is the prevalence of RSV infection. Different studies ...
bienco88's user avatar
1 vote
0 answers
287 views

Pooled samples: estimating prevalence of disease

Struggling to understand the concept of pooled sampling and estimation of prevalence. Would really appreciate some help to understand this. Example: 0.5% of the population has a specific disease. ...
TScott's user avatar
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3 votes
1 answer
113 views

Optimization of pool size and number of tests for prevalence estimation via group testing

I'm trying to devise a protocol for pooling lab tests from a cohort in order to get prevalence estimates using as few reagents as possible. Assuming perfect sensitivity and specificity (if you want ...
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Detect apparent prevalence [duplicate]

I have farms in my dataset and from each farm, I have a few animals (varies for each farm) to test for a disease. I want to know, if I tested these animals, what apparent prevalence will I be able to ...
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Is it possible to estimate prevalence from a given sample size?

I have farms in my dataset and from each farm, I have a few animals (varies for each farm) to test for a disease. I want to know, if I tested these animals, what apparent prevalence will I be able to ...
Abby's user avatar
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1 vote
1 answer
434 views

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

In cancer research, like in this article, partial prevalence is sometimes used to assess the epidemiological state of a disease in a population. The document I'm trying to understand (link, in french) ...
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