Unit 3, Ch 4

Question 1

Identify confounding variable

Answer 1

• How it’s associated with expl var
• How it’s associated with response var

Question 2

Level

Answer 2

Different value of a factor

Question 3

Factors and Levels

Answer 3

Factors: category
Levels: value for each category
Ex. Factor: fertilizer, water
Ex. Levels: For fertilizer -> 0 lbs, 20 lbs
For water -> 0 cups, 5 cups

Question 4

4 Principles
R,R,C,C
RaReComCon???

Answer 4

Randomize - select randomly, least bias
Replicate - use multiple subjects for consistent results
Control - keep variables constant
Comparison - compare 2+ treatments

Question 5

Blinding (2 types)

Answer 5

Single: subjects don’t know what treatment they have
Double: testers and subjects don’t know what treatment they have

Question 6

Random Assignment (3 steps)

Answer 6

Label - label the subjects you’re randomizing
Randomize - RNG, hat draw, etc
Assign - put subjects in corresponding levels

Question 7

Placebo effect

Answer 7

A false treatment (subjects may think it’s giving the same effect and can cause psychological changes)

Question 8

Flowchart

Answer 8

• Subjects
• Randomization
• Group 1, group 2, etc…
• Treatment 1, treatment 2, etc…
• Compare
• Underneath, write how subjects will be assigned (LRA)

Question 9

Block design

Answer 9

Groups of similar subjects
- not necessarily a factor being studied. Splits factors so different effects can be considered

Question 10

Stratified vs Block

Answer 10

Stratified: survey
Block: experiment

Question 11

Matched Pairs Design

Answer 11

Type of block. Pairs of similar units
Ex.
1st subj -> trtmnt 1 -> trtmnt 2
2nd subj -> trtmnt 2 -> trtmnt 1

Question 12

Sampling
SRS

Answer 12

Every group of given individuals has the same chance of being chosen

Ex. 2500 people, want to choose 250.
Choosing 200 males and 50 females is NOT SRS!!! It’s not truly random (ex. getting 250 males and no females, or 100 males and 100 females, etc)

Question 13

Sampling
Systematic

Answer 13

Picking by intervals
Ex. Choosing every 5 students to be part of experiment

Question 14

Sampling
Cluster

Answer 14

Split into groups -> choose group -> sample everyone from each group
ALL from SOME

Question 15

Sampling
Stratified

Answer 15

Split into groups -> SRS from each group
SOME from ALL
- Can be trait based

Question 16

BIASED Sampling
Voluntary Response

Answer 16

sample involves indvls who choose to participate

Question 17

BIASED Sampling
Convenience Sampling

Answer 17

sample involves indvls who are easy to reach

Question 18

Undercoverage Bias

Answer 18

part of population less likely to/can’t be chosen
- may not represent true variety of population
(Sampling process)

Question 19

Response Bias

Answer 19

inaccurate response due to wording/connotation or external influences
- forces responders to pick specific side
Ex. Guns kill millions of animals a year. Do you support the 2nd amendment?
Another ex. a teacher asks if students like his/her class. Students may feel inclined to respond positively (not honest answer)

Question 20

Non-response bias

Answer 20

part of population doesn’t respond/can’t be reached
(Response process)

Question 21

Observational Study

Answer 21

observes + measures variables of interest

Question 22

Experiment

Answer 22

imposes treatment to measure response

Question 23

Treatment

Answer 23

conditions imposed on subject

Question 24

Experimental unit

Answer 24

what’s being tested on
- if it’s a human, it’s called a subject

Question 25

Is random sample generalizable?

Answer 25

yes

Question 26

What does random assignment ensure?

Answer 26

Treatment actually causes change in response var (varied subjects = more uniform result)