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Are diagnostic tests and clinical (risk) prediction models in medicine essentially the same thing?

In medicine, are diagnostic tests (e.g. covid test, HIV test, ...) and risk prediction models essentially the same thing? If not, in which aspects do they differ (from statistical point of view)? ...
sitems's user avatar
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4 votes
2 answers
189 views

What data are used to find the final threshold for a medical diagnostic test?

Suppose I have some blood measurement X whose values correlate with some disease Y (so people with the disease use to have larger values of X). Moreover suppose that the disease is rare, say 1% of a ...
sitems's user avatar
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10 views

Mixed modal MANOVA or something else?

I am once again asking for your help. I am developing a research proposal and I am a bit confused. I have a randomized controlled trial (RCT) for testing the efficacy of a therapeutic intervention, in ...
user2205's user avatar
0 votes
1 answer
44 views

Cohen's d effect size of a medication

Studies use Cohen's d effect size to convey the effectiveness of an intervention. As a general rule in psychology, an effect size of 0.2 is considered small, 0.5 is medium, and 0.8 is large. Suppose ...
Spock366373's user avatar
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0 answers
13 views

How to check if an intervention helps a continuous variable (angle) stay within normal limits?

I have two different surgical interventions, and they are both used to treat cervical stenosis. One of the predictors of long-term success is the spinal alignment (relative angles of the vertebra). ...
Bilal Bahadır Akbulut's user avatar
0 votes
0 answers
9 views

Can Cox or Fine-Gray model include exposure that occurs during observation?

I'm making a Fine-Gray model about pregnancy, but I notice that some pregnancy complications may occur during the observation instead of at the beginning of it because those complications are often ...
黑月盟月's user avatar
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0 answers
5 views

Comparing the pattern of commensal of two drugs over time

I would naturally appreciate your advice on the following problem: Following operations, patients can be started either Drug A or Drug B to prevent blood clots forming in patients calves. We surveyed $...
Naren's user avatar
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0 answers
16 views

linear mixed model or non-linear mixed model

I´m in the medical field and study biomarkers. I study a biomarker that after a worsening of symptom, first increase and then decrease. It´s almost like the kinetics of blood-glucose after you eat. I ...
Magnus Johnsson's user avatar
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0 answers
29 views

Determining inflection point/ threshold values from a Cox regression using cubic splines

I am interested in looking at the impact of time to diagnosis of cancer on death. I will be modelling time to dx as a continuous predictor using cubic splines. I am also interested in determining a ...
user405452's user avatar
2 votes
1 answer
65 views

Analysis of Alzheimer data

I have two data sets with values from Alzheimer's and healthy patients. My task is to find a decision rule for evaluating the patients. The task in the original wording: "Think of a decision rule ...
aren's user avatar
  • 23
2 votes
1 answer
25 views

Missing data for Cox regression and HR

I'm conducting a research in which patients went through a surgery, for some the surgery was successful (outcome = 1) and for some it wasn't (outcome = 0). The risk factors were calculated using a Cox ...
AREEEL's user avatar
  • 21
3 votes
1 answer
36 views

Best subgroup identification - Cox regression, biomarker performance

We are working on a blood value biomarker type (lets call it NEW_bm) for a specific disease. We got data of 4 years follow-up and did a multivariable Cox-regression to see, if it has predictive ...
Julia Rose's user avatar
0 votes
1 answer
56 views

Statistical Genetics - How to interpret data & analysis

My question is how to interpret $G_{ij}$ in the following statistical genetic model $$h(\mu_i) = \alpha_0 + \alpha'X_i + \beta'G_i,$$ where $G_i = (G_{i1},\dots ,G_{im})$ are allele counts (zero, one, ...
Kevin's user avatar
  • 3
2 votes
2 answers
114 views

Controlling for number of days when calculating medication adherence

I am trying to evaluate the success of a medication adherence intervention. I am trying to assess the success of the program before and after the intervention in terms of number of days a patient took ...
NC8389's user avatar
  • 21
1 vote
1 answer
32 views

Univariant analysis in survival study

I don't know a lot about statistics and survival analysis so this might be a dull question. I'm performing a survival analysis where I want to study the possible risk or protective factors that could ...
Arthurr's user avatar
  • 73
5 votes
0 answers
24 views

Use of other ICU patients as control group

I am reviewing an article that is not yet published, so I cannot be too specific. Briefly, the authors did an unmatched case-control study. The cases were patients admitted to the ICU for a specific ...
Peter Flom's user avatar
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10 votes
3 answers
100 views

Can you legitimately claim to have used intention-to-treat analysis in a cluster randomised trial if recruitment occurs after randomisation?

In cluster-randomised clinical trials it is often the case that 'units', be they hospitals, practitioners or primary care centres etc., are randomised to the intervention or control arms prior to ...
user356816's user avatar
0 votes
1 answer
50 views

Should I include "Follow-up moment" as a fixed factor in my linear mixed model?

I am performing a linear mixed model to asses whether pain scores differ between surgically treated patients who tested positive for a bacterial culture versus negative. I have 5 follow up moments but ...
Bart Jonker's user avatar
8 votes
2 answers
121 views

Cannot seem to find a statistical difference despite a clear difference in the dataset

I've got a dataset of patients with AVM (neurosurgical disease) where you can receive endovascular treatment, surgical treatment or both (usually because endovascular treatment failed). My outcome is ...
Paze's user avatar
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0 votes
0 answers
18 views

Analyse the contribution of a specific, concomitant condition

I cannot think of an appropriate statistical test: I am conduction a retrospective chart review on patients. I'd like to see what a specific condition B (All patients have Condition A, several of them ...
Anthony's user avatar
0 votes
0 answers
17 views

Does it make sense to compare two different DVs on a within-subjects t-test or MANOVA (or ANOVA?)?

Let's say I have 3 different drug doses: A, B and C and I have two DVs: blood pressure and pulse. I am interested in finding out if the three doses differentially impact the two DVs (i.e. if at dose A ...
Arkansin's user avatar
0 votes
0 answers
12 views

Can different hazard ratios be compared?

Let's say study 1 finds a HR in group X vs control of 1.5. Study 2 finds a HR of 5.4 in group Y vs control. As I understand it, HRs involve the rate of the event happening. Since we do not know the ...
BigMistake's user avatar
0 votes
0 answers
19 views

Correcting for spillover bias in experiments?

Suppose I have an experiment designed where I'm interested in observing the effect of daily walking on self-reported joint pain in elderly adults. The population of interest are elderly adults who ...
jbuddy_13's user avatar
  • 3,278
3 votes
1 answer
132 views

Conditional probability of having intellectual disability

I'm reading this paper about a genetic disease. In the paper, there's the following table where $DD$ means developmental delay and $ID$ means intellectual disability. From the table (last column) we ...
alexmolas's user avatar
  • 288
1 vote
1 answer
71 views

Comparing binary and continuous predictors for diagnostic test

There is a "traditional" biomarker (binary predictor) used in the diagnosis of a disease (binary outcome) that has a high cost to perform for the clinical labs. I'm studying alternatives, ...
Daniel Nunes's user avatar
2 votes
1 answer
32 views

How to deal with patients falling out of the study more frequent in one treatment arm

I'm doing a retrospective comparison of two treatments (A and B) for eye disease. Both procedures have the same most common side effect (dependent variable) but their indications differ slightly ...
Mieszko's user avatar
  • 23
1 vote
1 answer
75 views

How do I modify logistic regression in my case (for repeated measures)?

I am a physician conducting some research in Critical Care patients (I have full ethical approval, none of my results will be used to inform patient treatment, etc). When a person's lungs are ...
for_the_love_of_cod's user avatar
0 votes
0 answers
21 views

Selecting correct study design and statistical analysis for my project

I am analyzing risk factors associated with surgical site infections where we want to have a 3:1 case-control study. Other than some brief lectures in my classes, the only thing we were taught about ...
Zaichik's user avatar
0 votes
0 answers
38 views

The choice of a statistical test to verify if there is significant difference between two categorical variables in a single population

Hello everyone I need some help with the choice of a statistical test to verify if there is significant difference between two categorical variables in a single population. I need to compare the ...
Francesco Ditonno's user avatar
1 vote
0 answers
37 views

Caveats in analyzing 2x2 contingency tables

after reading this paper https://onlinelibrary.wiley.com/doi/10.1111/1440-1681.12052 I have real troubles deciding which test is most suitable for my analysis. The data is following: a group of ...
YSN's user avatar
  • 111
3 votes
1 answer
117 views

Medical experimental design with non-comparable control

My population consists of people at high risk of cardiovascular disease who are identified through standard blood tests. These people, when identified, are prescribed some standard medication. I will ...
user2974951's user avatar
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2 votes
1 answer
32 views

How to correlate on sharp data changes

I'm trying to correlate changes in atmospheric pressure with headache intensity. I 'know' that there is a strong correlation in my case but out of curiosity I'm willing to take data for as long as I ...
Tanatarca's user avatar
  • 123
3 votes
1 answer
39 views

Estimating the percentage of a specific factor being related to a condition

I am working on a medical research project where I am trying to find the associations between specific maternal factors and neonatal limb ischemia (NLI) to declare the maternal factors as "risk ...
eddie's user avatar
  • 207
1 vote
1 answer
15 views

Correlating two variables

Im doing a medical research in which i have a cohort of 59 patients. I have data for each one about their blood level of a specific marker and data for each one about how many organs the disease I'm ...
Victor's user avatar
  • 11
0 votes
0 answers
24 views

How to identify variables with prognostic predictive value?

We have collected biopsy data and clinical data from 232 patients. The are in total 45 different clinical and histopathological variables available. What statistical method(s) is recommended to ...
Karl Gunnar Heart's user avatar
4 votes
1 answer
3k views

Is reporting univariate regression next to multivariate regression acceptable methodology?

In a paper published in Ebiomedicine (part of the Lancet family journals), the researchers built a logistic model including a variety of predictors and then reported both "univariate" ...
outofthegreen's user avatar
0 votes
1 answer
82 views

Validity of external cross validation using data generated by the fit model?

Context: A paper I'm reading uses PDEs to characterise the effects of cancer treatments on the tumour microenvironment. The exact wording used in the paper is: The predictive power of the [...
Kell's user avatar
  • 15
0 votes
1 answer
781 views

Fitting a linear mixed model on repeated measurements data, do I in- or exclude patients with only 1 observation?

I have a dataset of about 300 patients of which 100 have repeated observations of the outcome (2-6 observations per patient) and 200 have only 1 observation of the outcome. To determine what the risk ...
tcvdb1992's user avatar
  • 139
7 votes
5 answers
3k views

How to learn statistics for medical research?

I'm a last year medical student, as we say "Intern doctor". In the future I want to do research on the issue that I want to get in. Therefore I want to learn mathematics, statistics, R ...
3 votes
1 answer
32 views

Analysing non-outcome variables in meta-analysis

I am working on a meta-analysis project in suicidology. This is more like an academic exercise and will not necessarily be submitted for publication, but I try to be as rigorous as possible. Now here ...
user47679's user avatar
2 votes
1 answer
140 views

Help Requested - Bayes' Theorem posterior odds > 1 when applied to covid test

I took an antigen test yesterday and was trying to create a tool to help me interpret the results via Bayes' Theorem. I used actual sensitivity and specificity numbers from the CDC, calculated odds of ...
tenaciousjeebs's user avatar
1 vote
1 answer
154 views

One Feature to Rule Them All: Too Good to be True?

I am trying to build a ML model for diagnosing a certain group of several related but distinct diseases. Using a publicly available medical dataset, I performed data cleaning and feature extraction, ...
rbf's user avatar
  • 13
2 votes
0 answers
60 views

Ratio of means for a medical meta-analysis

I am in the process of pooling and analysing data from various studies for a meta-analysis I am working on. My supervisor (non-statistician) is keen for us to have the ratio of means which was ...
Coding Medic's user avatar
0 votes
1 answer
105 views

Comparing median scores in two groups and estimating/quantifying the difference

I have two groups (A and B) and data on 3 different biomarkers (a, b and c). What I need to investigate if there is any difference between the groups in each biomarker, and if the difference between ...
Med stud Karl's user avatar
0 votes
0 answers
15 views

Question about Most Appropriate Analysis for Repeated Measures (heart function)?

More of a general question. I have a dataset in which each subject undergoes a specific intervention. I have their pre-intervention heart function and then their 6-month and 12-month post-intervention ...
user2930701's user avatar
1 vote
0 answers
15 views

Growth mixture model to establish trajectories of maternal depressive symptoms

We have been trying to conduct a growth mixture model to establish trajectories of maternal depressive symptoms. We have managed to set up a model in MPlus and it runs, but we have a few theoretical ...
Stefani Du Toit's user avatar
2 votes
0 answers
47 views

Analysis for time to event

In a study I am conducting, I am looking at the time to event (use of opioid analgesic) as a marker of effective analgesia (pain relief) effect for morphine given intrathecally prior to the operation. ...
rolexEdwards's user avatar
8 votes
3 answers
673 views

Is it possible to have 1e-15 p-value when difference is about 1 SD?

The question is about the 2nd data table from the article Symptom improvement in children with autism spectrum disorder following bumetanide administration is associated with decreased GABA/glutamate ...
kirilloid's user avatar
  • 183
1 vote
0 answers
31 views

Using surgeon-level outcome rate as a predictor of outcome in logistic mixed model regression

I'm working on a study that involves predicting a surgery binary outcome (bailout yes vs. bailout no) in a hospital patient dataset. We wanted to include surgeon-level variables in a mixed model and ...
user324671's user avatar
1 vote
1 answer
53 views

Hypothesis testing - Thesis

I am doing a thesis project in which I need to answer three hypothesis, one measures the direct effect of health consciousness (high vs. low level) on healthy grocery shopping behaviour (high vs. low)...
Max1234's user avatar
  • 11