Question: At one time, a method called "gastric freezing" was used to treat people with peptic ulcers. An inflatable bladder was inserted down the esophagus and into the stomach, and then a cold liquid was pumped into the bladder. Now you can find the following notice on the Internet site of a major insurance company: [Our company] does not cover gastric freezing (intragastric hypothermia) for chronic peptic ulcer disease. Gastric freezing for chronic peptic ulcer disease is a non-surgical treatment which was popular about 20 years ago but now is seldom performed. It has been abandoned due to a high complication rate, only temporary improvement experienced by patients, and a lack of effectiveness when tested by double-blind, controlled clinical trials. What did that "controlled clinical trial" (experiment) probably look like? (Don't worry about "double-blind"; we'll get to that soon.)
a) What was the factor in this experiment?
b) What was the response variable?
c) What were the treatments?
d) How did researchers decide which subjects received which treatment?
e) Were the results statistically significant?