When subjects in both the treatment and control group exhibit favorable responses, the condition is an example of

a. the hawthorn effect, an improvement merely because of a change from the status quo

b. the placebo effect

c. an experiment that is confounded

d. the regression fallacy

e. blocking to reduce variation

A randomized block design is similar to which of the following sampling designs?

a. simple random sample

b. multi-stage cluster sample

c. stratified sample

d. convenience sample

e. systematic sample

Blocking is utilized to help

a. organize the treatment and control groups

b. counteract the placebo effect

c. produce groups that are as similar as possible

d. replicate the experiment within each block

e. avoid the need for randomization

Which of the following is not a valid sample design?

a. Code every member of a population and select 100 randomly chosen members.

b. Divide a population by gender and select 50 individuals randomly from each group.

c. Select individuals randomly and place into gender groups until you have the same proportion in the groups as in the population.

d. Select five homerooms at random from all the homerooms in a large high school

e. All of these are valid.