DATA Step, Macro, Functions and more

Calculating sensitivity and specificity values of a confusion matrix

Reply
Occasional Contributor
Posts: 16

Calculating sensitivity and specificity values of a confusion matrix

Hi Everyone, I am interested in learning how to write up SAS code to calculate sensitivity and specificity in my confusion matrix (5X5 table) below. Any help would be greatly appreciated Smiley Happy.

                                                                                Program

Syndrome                  Diarrheal-toxin          EC           Salmonella           Viral             Vomiting-toxin

Diarrheal-toxin                 50                         1                   0                    2                       0

EC                                  0                         25                  8                    0                       0

Salmonella                      1                         20                252                  6                        1

Viral                                4                         0                    0                   786                    39

Vomiting-toxin                  2                        0                     0                   0                        41

Thank you in advance


Super User
Posts: 17,942

Re: Calculating sensitivity and specificity values of a confusion matrix

How are you defining specificity and sensitivity in your particular case?

Occasional Contributor
Posts: 16

Re: Calculating sensitivity and specificity values of a confusion matrix

Hi Reeza, sorry I am defining mine as those syndrome outbreaks that are correctly classified in their respective program. For example, I calculate the sensitivity of diarrheal-toxin manually to be 94.3% (50/53).

Super User
Posts: 17,942

Re: Calculating sensitivity and specificity values of a confusion matrix

I don't recall specificity either (and don't feel like looking it up) but the general idea for sensitivity is simple enough.

data want;

set have;

array cause(5) diarrheal ec salmonella viral vomit;

total=sum(of cause(*));

sensitivity=cause(_N_)/total;

run;

Occasional Contributor
Posts: 16

Re: Calculating sensitivity and specificity values of a confusion matrix

Thank you sorry. I should have fully place the definitions up-my apologies but specificity is the probability of the syndromal outbreaks negative for a particular program given that it is not correctly classifed.

Ask a Question
Discussion stats
  • 4 replies
  • 528 views
  • 0 likes
  • 2 in conversation