Ariosto has developed a new kind of antibiotic. For the antibiotic to be sufficiently effective, it has to kill at least 90% of bacteria when applied to a harmful bacteria culture. He applied his antibiotic to one petri dish full of harmful bacteria – petri dish A. However, he did not apply the antibiotic to another identical petri dish that he had – petri dish B. (Ariosto successfully used cloning in order to ensure that petri dish B was in fact identical to petri dish A at the very beginning of the study).

Ariosto then analyzed the two petri dishes. He found that 97% of the bacteria in petri dish A were dead, whereas 0% of the bacteria in petri dish B were dead.

What type of statistical study did Ariosto use?