I have developed an non invasive risk assessment tool to estimate the stenotic risk of atherosclerosis to detect asymptomatic individuals. The carotid duplex will be the standard measure.
My question is:
For tool validity, should l apply the tool and carotid duplex on two groups (diseased and at risk) or only for one group ( at risk) ?
Second question:
Is fisher et al.,1998 the best sample size equation for this study
n = z²pq/d²
first question:
do for the two cases cited
second question:
yes, this equation is correct
I think you should conduct a performance trial getting sensitivity and specificity, in that case you must perform both tests to every participant. In this cases are nomograms to calculate sample size for this parameters.
Dear our Prof .. Hello ,
using screening 2 x 2 table for sensitivity and specificity to know the validity of the test.
In other words we need to critically appraise the article on a diagnostic test?
In such article we are looking for the following:
Have the researchers compared the test to a reference [Gold Standard]; which means that patients have undergone the two tests.
Example: Gold standard [ The carotid duplex ]
Example of Screening Test: A non invasive risk assessment tool
Blinded comparison: The results of one should NOT be known to those who are applying and interpreting the other
How have the researchers justified the selection of the Gold Standard?
in the attached files : nomogram
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