To test the effect of a new exercise routine on muscle

Last updated: 7/8/2022

To test the effect of a new exercise routine on muscle growth, a researcher sets up the following experiment: 60 volunteers subjects (40 men and 20 women) of average build are selected to participate in the study. Their body mass and muscle sizes (biceps, thighs, etc.) are measured. The researcher gives all the men a DVD with the new exercise routine, and the women a DVD with a standard routine, but only the researcher knows this. The results of the experiment are likely to be invalid mostly because the gender of the patient is a confounding variable in this experiment. the subjects did not know if they were getting the real treatment. the treatment group and control group were not the same size. the subjects were volunteers. None of the above