Chapter 2: simulation of positive result from a high-specificity diagnostic test

If you were a physician given a positive test result from :

REPS=42420; %[first 20 are hits, next 400 are FA, next 2000 are misses, and last 40000 are CR]

keepgoing=1;

while keepgoing, counter=0;

samp=randi(REPS); %select a person from among all those tested

while samp>420, samp=randi(REPS); counter=counter+1; end

% Construct a questdlg with three options

choice = questdlg({['All of your ' num2str(counter) ' previous patients have received negative results. Your current patient has a positive test. Is disease present?']},'', {'Yes','No','Cancel'});

% Handle response

switch choice

case 'Yes'

if samp<21, disp(['You''re right!! disease WAS present'])

else disp(['wrong!! no disease here']); end

case 'No'

if samp>20, disp(['You''re right!! no disease here'])

else disp(['wrong!! disease was present after all']); end

case 'Cancel'

keepgoing=0; end, end