1.Identify which one of the four types of validity1. Measurement validity, 2. Statistical conclusion validity, 3. Internal validity, or 4. External validityis violated in each of the following scenarios. Explain your decision.

a.There were 10 fewer cases of obesity for every 100 people who underwent the exercise intervention (95% CI: -0.25, 0.05).

b.In a study of circadian rhythms and response time to a cognitive task, researchers ask study participants how many hours they slept the night before in order to divide them into groups based on sleepiness. They find that individuals who slept <7 hours do 2.0 times more poorly on cognitive tasks compared with individuals who slept 7 hours (95% C.I. 1.05-3.53), and conclude that sleepiness causes reduced cognitive ability.

c.In a randomized controlled trial of hormone replacement therapy and risk of stroke, many women did not complete the study protocol based on their randomized assignment. Because so many of the postmenopausal women randomized to receive hormone replacement ended up not taking it and so many of the women randomized to take the placebo ended up asking their private doctors for prescriptions, the researchers reported the trial results according to how the women were actually treated.

d.A study finds that coffee drinking is protective against hair loss (RR=3.27, 95% C.I. 2.14- 5.38). The study does not include any stratification or any other adjustment approach; however, authors do report that the coffee drinkers were more likely to be women than men, and that men were more likely to have hair loss than women.