Apnea of prematurity occurs when babies have shallow breathing or stop breathing for more than 20 seconds. One therapy for this condition is to give caffeine to the premature infants. Medical researchers conducted
an international study in which one sample of premature infants was randomly assigned to receive caffeine therapy and another sample received a placebo therapy. Researchers planned to compare the percent of
each group that experienced severely negative outcomes (death and severe disabilities) to determine whether the therapy would lower the rate of such bad events. The caffeine therapy group ended up with a 40%
"bad event" rate while the placebo group ended up with a 46% rate. The reserachers concluded that caffeine therapy did help reduce the occurrence of severely negative outcomes for premature babies with apnea.
laentify the four steps of this statistical study.