An experiment was carried out to determine the effect of providing free milk to school children in a certain district (Lanarkshire, Scotland). Some children in each school were chosen for the treatment group and got free milk, others were chosen for controls and got no milk. Assignment to treatment or control was done at random, to make the two groups comparable in terms of family background and health. After randomization, teachers were allowed to use their judgment in switching children between treatment and control, to equalize the two groups.
Are these statements true or false?
A. This is a probability sample
B. This is a simple random sample.
C. There is selection bias
D. There is non-response bias
