Experiments and Observational Studies

Question 1

A study based on data in which no manipulation of factors has been employed.

Answer 1

Observational Study

Question 2

An observational study in which subjects are selected and then their previous conditions or behaviors are determined.

Answer 2

Retrospective Study

Question 3

An observational study in which subjects are followed to observe the future outcomes. Not an experiment because no treatments are deliberately applied.

Answer 3

Prospective Study

Question 4

To be valid, an experiment must do this when assigning experimental units to treatment groups.

Answer 4

Random Assignment

Question 5

A variable whose levels are manipulated by the experimenter.

Answer 5

Factor

Question 6

A variable whose values are compared across different treatments.

Answer 6

Response Variable

Question 7

This manipulates factor levels to create treatments, randomly assigns subjects to these treatment levels, and then compares the response of the subject groups across treatment levels.

Answer 7

Experiment

Question 8

The individuals who participate in an experiment, especially when they are human.

Answer 8

Subjects or participants

Question 9

Individuals on whom an experiment is performed.

Answer 9

Experimental Unit

Question 10

The specific values that the experimenter chooses for a factor.

Answer 10

Levels

Question 11

The process, intervention, or other controlled circumstance applied to randomly assigned experimental units.

Answer 11

Treatment

Question 12

Control
Randomize
Replicate
Block

Answer 12

4 Principles of Experimental Design

Question 13

Do this to aspects of the experiment that we know may have an effect on the response, but that are not the factors being studied.

Answer 13

Control

Question 14

Do this to subjects of treatments to even out effects that we cannot control

Answer 14

Randomize

Question 15

Do this over as many subjects as possible.

Answer 15

Replicate

Question 16

Do this to reduce the effects of identifiable attributes of the subjects that cannot be controlled.

Answer 16

Block

Question 17

When this is done, all experimental units have an equal chance of receiving any treatment.

Answer 17

Completely Randomized Design

Question 18

When a observed difference is too large for us to believe that it is likely to have occurred naturally:

Answer 18

Statistically Significant

Question 19

The experimental units assigned to a baseline treatment level typically either the default treatment or a null, placebo treatment.

Answer 19

Control Group

Question 20

Any individual with an experiment who is not aware of how subjects have been allocated to treatment groups is this…

Answer 20

Blinded

Question 21

When either those who could influence the results OR those who evaluate the results are not aware of how subjects have been allocated to treatment groups, the experiment is this:

Answer 21

Single-Blind

Question 22

When either those who could influence the results AND those who evaluate the results are not aware of how subjects have been allocated to treatment groups, the experiment is this:

Answer 22

Double-Blind

Question 23

A treatment known to have no effect, administered so that all groups experience the same conditions.

Answer 23

Placebo

Question 24

The tendency of many human subjects (often 20% or more) to show a response even when administered a treatment known to have no effect.

Answer 24

Placebo Effect

Question 25

When groups of experimental units are similar in a way that is not a factor under study, use THIS to gather them together and randomize the assignment of treatments within each group.

Answer 25

Blocking

Question 26

An experiment design in which participants are randomly assigned to treatments within smaller groups based on similarities not under study.

Answer 26

Randomized block design

Question 27

In a retrospective or prospective study, do this with participants who are similar in ways not under study.

Answer 27

Matching

Question 28

When the levels of one factor are associated with the levels of another factor in such a way that their effects cannot be separated…

Answer 28

Confounding