4.5-4.9 AP stats

Experimental Study

Deliberately imposes some treatment on individuals to measure their responses.

Confounding Variable

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

Experimental Units

The smallest collection of individuals to which treatments are applied.

Subjects

Experimental units that are human beings.

Treatment

A specific experimental condition applied to the units.

comparison group

An experimental group whose primary purpose is to provide a baseline for comparing the effects of the treatments. Depending on the purpose of the experiment, it may be given a placebo or an active treatment

Placebo

An inactive (fake) treatment

Control

keeping potential confounding variables constant across all treatment groups

Replication

repeating an experiment or study to determine if the results are consistent and reliable, not due to random chance

Double Blind

An experiment in which neither the subjects nor those who interact with the subjects know which treatment a subject received.

Single Blind

An experiment in which either the subjects or those who interact with the subjects know which treatment a subject received

Statistically Significant

An observed effect so large that it would rarely occur by chance.

Randomized Block Design

Start by forming blocks consisting of individuals that are similar in some way that is important to the response. Random assignment of treatments is then carried out separately within each block.

Explanatory Variable

A variable that helps explain or influences changes

Response Variable

A variable that measures an outcome of a study.

Placebo Effect

Describes the fact that some subjects respond favorably to any treatment, even an inactive one.

Matched Paired Design

experimental units are paired based on a shared characteristic, such as age, gender, or a pre-test score

Completely Randomized Design

where experimental units are randomly assigned to treatment groups, giving each unit an equal chance of receiving any treatment.

Confidentiality

A basic principle of data ethics that requires individual data to be kept private.

Informed Consent

A basic principle of data ethics. Individuals must be informed in advance about the nature of a study and any risk of harm it may bring. Participating individuals must then consent in writing.

Institutional Review Board

A basic principle of data ethics. All planned studies must be approved in advance and monitored by an institutional review board charged with protecting the safety and well-being of the participants.

Four principles of Experimental Design

Comparison group, Random assignment, Replication, Control

purpose of random assignment

allows to conclude cause & effect

purpose of random sample

Allows to conclude findings to the whole population