Question

A scientist was asked to test the effect of a new vitamin for rats. His hypothesis was that young rats that had vitamins added to their food would gain weight faster than young rats fed a normal diet. He predicted that if young rats were fed vitamins, then they would gain more weight by the end of the experiment. He tested the effect of adding vitamins to some of the rats' diet by measuring the amount of weight each rat gained after three months. He then determined the average weight gained in each group. To analyze his results, he put the data he collected into the table shown below.
Which of the following could have added bias to the data?

 A.Keeping the rats in the same room, but in separate cages during the experiment B.Not using all male or all female rats, since they are different sizes when grown C.Recording the data in a table instead of on a graph D.Not having the experimental results peer reviewed

Answer 1

A: incorrect because there will be no effect on keeping the rats in separate cage in the same room at the time of the experiment.

C: incorrect because it's depend upon scientist whether he wants to record the observation on the graph or on the table. Thus, no affect will be caused on the observations.

D: incorrect because peer review is done only after the experiment is completed.

Thus, statement B is correct because the growth graph of male and female of any species is different. Male tend to grow more than their female counterparts. So, for the process of the study it is essential that all the rats included are either male or female.

Hence, option (B) is correct.

Answer 2

The control group was the rats fed the normal diet without added vitamins (apex)