During a clinical interview, survivors of a flood are asked to state "no" or "yes" to whether they have experienced specific symptoms of Post-Traumatic Stress Disorder (PTSD) in the past week. The interviewer adds up the total number of "yes" responses to create a Total PTSD Symptoms scale. What is the appropriate scale of measurement?

Nominal    

Explanation:

In statistics or research methods, a nominal scale is considered as the very first level of "measurement scale" wherein various numbers serve only as labels or tags in order to classify or identify a particular object. However, the nominal scale of measurement generally deals with only "non-numeric" i.e, quantitative variables or the place where different numbers don't have any value.

Example: Sex, religious affiliation, city, place, etc.

According to the question, the appropriate scale of measurement is the nominal scale.