#blocking

Question 1: Select all that apply

In a study, 38 men and 38 women volunteered. Within each sex, half were randomly assigned to eat 25 g of chia seeds twice a day and the other half to a placebo, and the participants did not know which they received. After 12 weeks there was no significant difference in weight loss between the groups. Which statements are true? Select all that apply.

Sex was used as a blocking variable.1
Had a significant difference been found, the random assignment would have allowed attributing it to the seeds.2
Because the participants volunteered, this is an observational study.3
Because the treatments were randomly assigned, the conclusion can be generalized to all adults.4

Timed test