# Questions tagged [diagnosis]

medical diagnosis: diagnostic accuracy and diagnostic research

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0answers
12 views

### Demonstrating that proposed cutoff score is non optimal

I have a small data set with a test score and classification (positive or negative diagnosis). There is already clinical evidence that the cut point suggested by the test manufacturer produces too ...
2answers
53 views

### Probability of disease in a patient with risk factor

I'm a doctor so I'm sorry for my basic knowledge of statisctics. I have a prior probability of the disease D $$P(D) = 0.12$$ I know that risk factor RF can cause the disease. Total probability of ...
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 ...
2answers
139 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). ...
0answers
28 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 ...
1answer
96 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 ...
1answer
262 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?
0answers
579 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 ...
0answers
91 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 ...
1answer
389 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 ...
1answer
34 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 ...
1answer
22 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. ...
5answers
3k 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: $.01$ ...
2answers
254 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. ...
2answers
460 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 ...
2answers
713 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,
2answers
875 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 ...