Ch 4 Section 2&3

Question 1

Experiment

Answer 1

Deliberately imposes some treatment on individuals to measure their responses
(Actually doing something to people)

Question 2

Confounding

Answer 2

Occurs when 2 variables are associated in such a way that their effects on a response variable cannot be distinguished from each other.

Question 3

Treatment

Answer 3

Specific condition applied to the individuals in an experiment
(What you are doing)

Question 4

Experimental units

Answer 4

Smallest collection of individuals to which treatments are applied
(Doing on/ to)

Question 5

Subjects

Answer 5

Units are human beings, they are called this

Question 6

Factors

Answer 6

explanatory variables in an experiment

Question 7

Level

Answer 7

Each treatment formed by combining a specific value of each of the factors

Question 8

Random assignment

Answer 8

Experimental units are assigned to treatments using a chance process.

Question 9

Completely randomized design

Answer 9

Experimental units are assigned to the treatments completely by chance.

Question 10

All experiments will have what?

Answer 10

Comparison
Random assignment
Control
Replication (doing it on enough subjects) 
CCRR

Question 11

What are the simplest statistical designs for experiments? What is this like?

Answer 11

Completely randomized designs for experiments

Like SRS are for samples

Question 12

Stratifying is to surveys as what is to what

Answer 12

Blocking is to experiments

Question 13

When should you block??

Answer 13

Block things only when there are things that will affect response variable

Question 14

Block

Answer 14

Group of experimental units known before experiment to be similar in some way that’s expected to affect the response to the treatment

Question 15

Randomized block design

Answer 15

Random assignment of experimental units to treatments is carried out separately within each block.

Question 16

____ what you can, ____ on what you want, and then ____ the create comparable groups

Answer 16

Control what you can, block what you want, and then randomize to create comparable groups.

Question 17

Matched pairs design

Answer 17

Common type of randomized block design for comparing 2 treatments
-create blocks by matching pairs of similar experimental units

Question 18

Ex of matched pairs design

Answer 18

Twins, shoes, match w self

Question 19

What can influence the response when dealing with matched pairs design? What should we do about this problem? Example?

Answer 19

Order of the treatments
So we randomize the order for each experimental unit
Cookie A & B, do in different order so the first cookie doesn’t taste better bc you were hungry

Question 20

Observational study

Answer 20

Observes individuals & measures variables of interest, but does NOT attempt to influence the responses. (Survey).
DOES NOT PROVE CAUSATION.

Question 21

What type of influence (or conclusion) can be made from a particular study?
What do they allow?

Answer 21

Answers depend on design of study.

• random selection of individuals, which allows inference about the population
• random assignment of individuals to groups, which permits influence about cause & effect

Question 22

Criteria for establishing causation when an experiment cannot be done?

Answer 22

Association must be strong
Association must be consistent
Larger values of the explanatory variable are associated with stronger responses
Alleged cause precedes the effect in time
Alleged cause is plausible