Polio Terms 1.1

Explanatory variable

The variable that is manipulated or controlled by researchers (the "cause" being tested).

Response variable

The variable that is observed or measured as an outcome (the "effect").

Treatment group

The group of subjects that receives the treatment being tested.

Control group

A separate group of subjects that does not receive the treatment, used for comparison.

Confounding factor

A variable, other than the explanatory variable, that can affect both the explanatory and response variables — making it hard to tell what actually caused the outcome.

Placebo

A fake treatment or inert substance with no therapeutic value, given to the control group so subjects don't know whether they got the real treatment.

Placebo effect

The phenomenon where people respond psychologically or physically to a treatment simply because they believe they're being treated — even if it has no real effect.

Blind study

A study where subjects don't know whether they're in the treatment or control group.

Double-blind study

A study where neither the subjects nor the researchers/evaluators know who received the treatment vs. the placebo.

Single-blind study

A study where the subject doesn't know their group, but the researcher does.

Randomization

Using an objective chance procedure (like a coin flip) to assign subjects to treatment or control groups.

Randomized controlled experiment

An experiment where subjects are randomly assigned to treatment or control groups, minimizing bias and confounding.

Causal inference

A conclusion that one variable causes a change in another — only reliably supported by well-designed experiments.