Waiting for answer This question has not been answered yet. You can hire a professional tutor to get the answer.
Read Article 5, "Physical Fitness of Police Officers as They Progress from Supervised Recruit to Unsupervised Sworn Officer Fitness Programs" in the
Read Article 5, “Physical Fitness of Police Officers as They Progress from Supervised Recruit to Unsupervised Sworn Officer Fitness Programs” in the Study Guide, and then answer the following question: How did the researchers control for external variables in this study?