Question

to test the effectiveness of a liquid supplement that is supposed to help forgetful people with their memory, 400 college students are recruited for a study and divided into two groups. group a with 250 students receives the supplement, while group b with 150 students receives some colored water. neither group is told what they received. after several weeks, they are given a memory test. this study can best be described as

• the placebo effect
• a survey using simple random sampling
• a survey using quota sampling
• a census
• a controlled placebo experiment

Explanation:

🆕 New Concept Discovered: Experimental Design in Statistics
Comparing treatments using a control group

Step 1: Identify the study structure

The study involves recruiting participants and actively dividing them into two distinct groups:

• Group A (Treatment Group): Receives the active liquid supplement.
• Group B (Control Group): Receives an inactive substance (colored water), which serves as a placebo.

Because the researchers are actively imposing a treatment rather than just observing or asking questions, this is an experiment, not a survey or a census.

Step 2: Analyze the role of the placebo and blinding

• The colored water given to Group B acts as a placebo (an inactive treatment designed to look like the real thing).
• The participants do not know which treatment they received ("Neither group is told what they received"), which is called blinding. This controls for psychological expectations.
• Since there is a treatment group, a control group receiving a placebo, and blinding, this setup is a classic controlled placebo experiment.

Answer:

a controlled placebo experiment