Questions tagged [diagnosis]

medical diagnosis: diagnostic accuracy and diagnostic research

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11
votes
5answers
2k views

Interpretation of Bayes Theorem applied to positive mammography results

I'm trying to wrap my head around the result of Bayes Theorem applied to the classic mammogram example, with the twist of the mammogram being perfect. That is, Incidence of cancer: $.01$ ...
5
votes
2answers
246 views

Which statistical model to use when trying to find the beginning of a time-dependent increase

I have a repeated measures data set with time as the independent variable and a single dependent variable, y. That is, for each subject, I have a certain (small, from 1 to 3) number of measurements. ...
4
votes
0answers
42 views

Correction for multiple testing required for combined metrics

Let's say I compare two diagnostic procedures (A and B) and want to check if one outperforms the other one using the metric diagnostic accuracy where diagnostic accuracy is commonly described using ...
3
votes
2answers
249 views

What happens with sensitivity and specificity after a second test?

What happens with sens/spec and PPV/NPV if one performs a test twice (or three times etc.)? I will give an example from my own clinical practice. At many hospitals we have a problem with ...
2
votes
2answers
829 views

Relationship between ROC curve and statistical significance in comparison of two groups

My question is about any possible relationship between the significance of a comparison test (Mann-Whitney U) and the ROC curve. If the comparison test is strongly significant, should we expect a ...
2
votes
1answer
28 views

Conflicting definitions of logistic regression

I do diagnostic research and am interested in determining how the probability of a patient having cancer is related to the concentration of different molecules in the blood. I have received ...
2
votes
1answer
21 views

when add-on test is necessary? better diagnosis strategy

Suppose there are two types of tests available. Test A: low-cost, but relatively less precise; Test B: high-cost, but more precise. Test B can be considered as the good standard with 100% accuracy. ...
1
vote
1answer
336 views

Over-fitting diagnosis method

How much difference between train and test set errors can indicate over-fitting? For example in logistic regression. I am trying to classify 11746 comments based on their sentiments in three classes ...
1
vote
1answer
82 views

Network meta-analysis of correlation coefficients: a logical paradox?

A colleague of mine wishes to conduct a network meta-analysis of correlation coefficients for a set of imaging tests (eg ultrasound, computed tomography, magnetic resonance imaging, and so forth). ...
1
vote
1answer
200 views

Network meta-analysis of diagnostic test accuracy studies

I need to make a network meta-analysis of diagnostic studies. Is there a good explanation to do it with R?
1
vote
1answer
458 views

Estimate ROC curve using binormal distribuiton

I am conducting a meta-analysis on diagnostic studies but for each study I have only mean and standard deviation reported. How can I estimate the ROC curve using the binormal assumption in R ? Tks,
1
vote
0answers
402 views

Calculating sensitivity and specificity from survival data

I have a diagnostic test performed on 100 participants at baseline. I then follow up these participants for variable periods of time and have data regarding survival. I have used a Cox regression ...
1
vote
0answers
77 views

Handling incomplete information properly when using Bayes' theorem

Just for fun I'm trying to do some simple medical diagnosis using Bayes' theorem. Right now I'm calculating ...
0
votes
0answers
8 views

Estimating a learning curve without gold standard

Consider the outcome of a diagnostic tool in medicine: each patient has either the disease or is disease-free (0/1). Now, let's further assume that it is not possible to have a false-positive, i.e. ...
0
votes
0answers
22 views

How to calculate the reclassification calibration statistic (RC statistic)?

In risk prediction models there is a need to evaluate the added diagnostic value of a new variable (biomarker). Different measures have been suggested, among them there is the reclassification ...
0
votes
0answers
26 views

Assess sensitivity of a binary screening result across other continuous covariate(s)

I want to assess the sensitivity of a diagnostic screening test, which is a binary test (screen +ve and screen -ve). There is no continuous measure from this test - it is literally yes or no. My ...
0
votes
1answer
70 views

Post-hoc power calculation for AUC analysis, to evaluate a new diagnostic test in a cohort

I need some urgent advice for a grant application. I am evaluating a new diagnostic test and at the last minute a Professor has offered me the dataset from a completed prospective study of the disease ...