Suppose a researcher was interested in effect of milk on children's height. The researcher recruited 20,000 schoolchildren and measured their height. They randomly allocated pupils to either receive milk or no milk, but they told teachers that if it appeared that if either the milk or the no milk groups in their classroom appeared to have more well-nourished children, they could even the groups out. After the experiment it was found that the children in the milk condition had grown more (but their average height was still less than the no milk group). Which of the following is the biggest problem with this study?
A) The sample size is too large.
B) There was a bias in the allocation of participants to conditions.
C) The group that gains the most height must be taller, there were problems in the calculations.
D) The placebo effect.

Question

Quizplus · Accepted Answer

The biggest problem with this study is the bias in the allocation of participants to the conditions. The fact that the teachers were allowed to even out the groups based on their perception of well-nourished children introduces a potential for systematic differences between the groups that may have influenced the results. The large sample size is actually a strength of the study, and the other options are not relevant to the specific issues with this design.

Suppose a Researcher Was Interested in Effect of Milk on Children's