An advertisement in a medical journal stated that "2,000 subjects with sore throats were treated with our new medicine. Within 4 days, 94% were asymptomatic." The advertisement claims that the medicine was effective. Based on the evidence given above, the claim:
a. Is correct
b. May be incorrect because the conclusion is not based on a rate
c. May be incorrect because of failure to recognize a long-term cohort phenomenon
d. May be incorrect because no test of statistical significance was used
e. May be incorrect because no control or comparison group was involved
Answer: e. May be incorrect because no control or comparison group was involved