Does donating blood lower cholesterol levels? 50 volunteers have ...

[D2AR0N]

Does donating blood lower cholesterol levels? 50 volunteers have a cholesterol test, then donate blood, and then have another cholesterol test. Which aspect of experimental design is present?
 
  A) randomization
  B) none of these
  C) a control group
  D) a placebo
  E) blinding

Question 2

In an experiment the primary purpose of blinding is to reduce
 
  A) confounding.
  B) variation.
  C) randomness.
  D) bias.
  E) undercoverage.

[pikon]

Answer to Question 1

B

Answer to Question 2

D