A research design where every condition is held constant except one tested factor is called what?

A research design where every condition is held constant except one tested factor is called what?

• A. A randomized trial
• B. A blind study
• C. A controlled experiment
• D. An observational study

Answer: (C)

Isolating the effect of a single variable by keeping all other conditions fixed defines a controlled experiment. In this setup, the factor being tested is the only thing that changes between conditions, so any observed difference can be attributed to that factor rather than to other influences. A control group provides a baseline by experiencing the same conditions minus the tested factor, helping to show what would happen without the treatment. Randomization and replication often accompany this design to reduce bias and improve reliability. The other study types describe different approaches: a randomized trial emphasizes how participants are assigned to groups, a blind study reduces bias in measurement by concealing group assignments, and an observational study collects data without manipulating any variables.

Isolating the effect of a single variable by keeping all other conditions fixed defines a controlled experiment. In this setup, the factor being tested is the only thing that changes between conditions, so any observed difference can be attributed to that factor rather than to other influences. A control group provides a baseline by experiencing the same conditions minus the tested factor, helping to show what would happen without the treatment. Randomization and replication often accompany this design to reduce bias and improve reliability. The other study types describe different approaches: a randomized trial emphasizes how participants are assigned to groups, a blind study reduces bias in measurement by concealing group assignments, and an observational study collects data without manipulating any variables.