1. Identify which one of the four types of validity--measurement validity, statistical conclusion validity, internal validity, or external validityis violated in each of the following scenarios. Explain your decision. (20 points)

In a longitudinal study of exposure to formaldehyde and cancer, people from the Lower Ninth Ward who lived for more than six months in a FEMA trailer following Hurricane Katrina were compared to people whose homes were spared in the elegant Garden District of New Orleans.Students were interviewed in a group setting and asked questions about their attitudes toward dating and sex.Citing a South African study that found that circumcision reduced mens risk of contracting HIV by 45%, the head of urology at a large Midwestern hospital encouraged his uncircumcised patients to undergo the procedure.There were 10 fewer cases of obesity for every 100 people who underwent the exercise intervention (95% CI: -0.25, 0.05).