1.1 Describe the selection bias likely to exist in the following situations.

a. A study of 3600 Australian children showed that children who sleep early and wake up early have a lower BMI as compared to children who sleep late and wakeup late.

Therefore, children who are early sleepers are healthier than children who go to sleep late.

b. A study of 1500 college students found that students who studied in a private school scored better in first year of college than students who studied in a government-aided school. Therefore, education from a private school improves a student’s academic performance.

c. A study of 2500 women in Sweden claims that young women who play video games for an hour every day are more likely to become obese than women who do not play them at all.