Answer:
Sampling bias
Step-by-step explanation:
Bias refers a prominent problem in statistical analysis whereby one or more analytical factor are favored than the other during an analysis which should be made random. The problem. With Graham's dissertation study is the fact that he failed to randomlyvplace his subjects or observation in the study groups, favoring a particular group with non random subset. When randomization is ejected or missing from an analysis or study, it becomes less and less representative. Here, allotting early Arrivals Into the treatment group has introduced a sampling bias as those who came later, this will also leads to less reproducibility of experiment.
