Understanding Experimental Design and Variables

These flashcards cover key concepts related to experimental design, response and explanatory variables, confounding, and various experimental methods.

What is a response variable?

A response variable measures an outcome of a study.

What is an explanatory variable?

An explanatory variable may help explain or predict changes in a response variable.

What is confounding?

Confounding occurs when two variables are associated in such a way that their effects on a response variable cannot be distinguished from each other.

What is an observational study?

An observational study gathers data on individuals as they are, without attempting to influence responses.

What is an experiment?

An experiment deliberately imposes some treatment on individuals to measure their responses.

What is a treatment in the context of an experiment?

A treatment is a specific condition applied to individuals in an experiment, often a combination of specific values of explanatory variables.

What is an experimental unit?

An experimental unit is the object to which a treatment is randomly assigned.

What is a factor in an experiment?

A factor is a variable that is manipulated in an experiment and may cause a change in the response variable.

What are levels in the context of experimental factors?

Levels are the different values of a factor in an experiment.

What is a placebo?

A placebo is a treatment that has no active ingredient but resembles other treatments.

What is a control group?

A control group provides a baseline for comparing effects of other treatments.

What is the placebo effect?

The placebo effect describes the phenomenon where subjects respond favorably to any treatment, including an inactive treatment.

What is a double-blind experiment?

A double-blind experiment is one where neither subjects nor those measuring responses know which treatment a subject received.

What is a single-blind experiment?

A single-blind experiment is where either the subjects don't know which treatment they are receiving or the people measuring responses don't know.

What does statistical insignificance mean?

Statistical insignificance means a difference in the response variable that may not be reliable due to variability, often due to a small sample size.

What is random assignment in experiments?

Random assignment means that experimental units are assigned to treatments using a chance process.

What does control mean in an experiment?

Control means keeping other variables constant for all experimental units to avoid confounding.

What is replication in an experiment?

Replication means using enough experimental units to distinguish treatment effects from chance variation.

What is a completely randomized design?

In a completely randomized design, experimental units are assigned to treatments by chance.

What is a block in the context of randomized block design?

A block is a group of experimental units known to be similar in a way expected to affect response to treatments.

What is a randomized block design?

In a randomized block design, random assignment of experimental units to treatments is done separately within each block.

What is a matched pairs design?

A matched pairs design is an experimental design that compares two treatments using blocks of size 2.