Ch 9; Producing Data: Experiments

Question 1

Observational Study

Answer 1

Observes individuals & measures variables of interest but does not attempt to manipulate variables

Question 2

Experiment

Answer 2

Deliberately imposes some treatment/variable on individuals to observe their responses. (Study whether treatment causes change in response)

Question 3

Confounding Variables

Answer 3

2 Variables (explanatory/lurking) are confounded when their effects on a response variable can’t be distinguished from each other.

Question 4

Explanatory Variable

Answer 4

When a variable is codependent on another

Question 5

Lurking Variable

Answer 5

Unknown variable that has a significant effect on the variables of interest.

Question 6

Subjects

Answer 6

Individuals studied in experiments

Question 7

Factors

Answer 7

Explanatory variables

Question 8

Treatment

Answer 8

Any specific experimental condition applied to subjects

Question 9

What Factors could Make A Experiment Not Work

Answer 9

Uncontrolled experiments that experience confounding variables.

Question 10

Randomized Comparative Experiment

Answer 10

An experiment that uses both comparison of 2+ treatments & random assignment of subjects to treatments

Question 11

Control Group

Answer 11

Group that receives a “standard” treatment (placebo) & provides a basis of comparison

Question 12

Completely Randomized Design

Answer 12

All subjects are allocated at random among all treatments

Question 13

What Reduces Chance Variation in Experiments

Answer 13

Replication or large number of subjects

Question 14

List the 3 Principles of Experimental Design

Answer 14

1) Control; Restrict effects of lurking variables on the response, by comparing 2+ treatments
2) Randomization; Use chance to assign subjects to treatment
3) Replication; Use enough subjects in each group to reduce chance variation in results.

Question 15

Statistical Significance

Answer 15

An observed effect so large it would rarely occur by chance

Question 16

Factors that Make A Study Better (2)

Answer 16

Placebo, Blind (Single/Double)

Question 17

Placebo Effect

Answer 17

Favorable response even though not receiving treatment (Generally given to control group)

Question 18

Single Blind

Answer 18

The subjects don’t know if they received placebo/treatment

Question 19

Levels

Answer 19

A particular value/category of factor

Question 20

Double Blind

Answer 20

Neither subjects or people who interact with subjects know which treatment each subject is receiving.

Question 21

Matched Pairs Design

Answer 21

Compares just 2 treatments & chooses pairs of subjects that are as closely matched as possible. (Randomize within pair)

Question 22

Block Design

Answer 22

The random assignment of individuals to treatments is carried out separately within each block

Question 23

Block

Answer 23

A group of individuals that are known before experiment to be similar in some way that is expected to affect response to treatments (gender).