neither the experimenter nor the subjects know who is receiving the real treatment or the placebo. this type of study is called:

Which sentences do not meet the requirements of an effective thesis statement? select all that apply. due to educational cutbacks, we really need your to buy new softball and baseball equipment. if you donate to our cause, you will receive free tickets to all our school's sporting events. your generous donation will allow our school to offer softball and baseball this year. in addition to free tickets, we will allow you to hang an advertising banner on the outfield fence. if you donate to support our cause, you will not only receive free tickets and a free advertising opportunity, you will earn the devotion and loyalty of many within our school.