Intro to Stats: Videos & Practice Problems

"Double-blind" means neither the participants nor the investigators who interact with them know the assignments; it is important because it prevents both placebo effects and observer-expectancy effects that could bias self-reported pain scores.

"Double-blind" means that participants do not know the purpose of the study and investigators do not know the study hypothesis; it is important because it keeps everyone unbiased about the goals.

"Double-blind" means both the treatment and the outcome are hidden from public reporting until the end; it is important because it prevents early leaks of results.

"Double-blind" means two independent statisticians analyze the data separately; it is important because it ensures computational accuracy.