Studies made by Kate as a university student have shown that people over age 60 who donate blood twice a year are less likely to die from a heart disease during the following year than those who do not donate. However, recent research has shown that people over age 60 who donate blood twice a year are also less likely to die from any cause during the following year than those who don't donate. Are there any confounding variables that make it difficult to justify a cause-and-effect conclusion?
A) Yes
B) No

Question

Quizplus · Accepted Answer

There may be other variables besides blood donation that affect the likelihood of death in the following year, such as overall health status or access to healthcare. Therefore, it is difficult to conclude that blood donation is the sole cause of the lower mortality rate observed.

Studies Made by Kate as a University Student Have Shown