Chapters 1-6.2

Question 1

cluster sample

Answer 1

• first divide population into smaller groups (ideally, these clusters should mirror the characteristics of the population i.e. by location)
• then choose an SRS of the clusters
• all individuals in the chosen clusters are included in the sample

Question 2

stratified sample

Answer 2

• first classify the population into groups of similar individuals called strata (ex. undergraduate and graduate)
• choose a separate SRS in each stratum and combine these SRSs to form the sample

Question 3

stratified or SRS

Answer 3

stratified samples give more precise info about population than SRS

Question 4

what is an SRS

Answer 4

consists of individuals chosen in such a way that every set of individuals has an equal chance of getting selected

Question 5

what is undercoverage

Answer 5

occurs when members of the population are left out of the process of choosing a sample (don’t participate) ex. calling people’s houses during weekday working hours

Question 6

what is non-response

Answer 6

occurs when an individual chosen for the sample can’t be contacted or refuses to participate

Question 7

what is wording of questions

Answer 7

confusing or leading questions can introduce strong bias, and changes in wording can greatly change a survey’s outcome

Question 8

what are the two main types of bias

Answer 8

• convenience

- voluntary

Question 9

what is convenience bias

Answer 9

a sample selected by taking the members of the population that are easiest to reach
ex. first people to arrive at a game

Question 10

what is voluntary response bias

Answer 10

people decided whether to join a sample based on open invitation

Question 11

what is response bias

Answer 11

systematic pattern of incorrect answers in a sample survey

Question 12

what is an observational study

Answer 12

observes individuals and measures the variables of interest but does not attempt to influence the responses

Question 13

what is an experiment

Answer 13

deliberately imposes some treatment on individuals to measure their responses
-only source of fully convincing data to understand cause and effect

Question 14

what is a lurking variable

Answer 14

a variable that is not among the explanatory or response variables in a study but that may influence the response variable (ex. how long you study for a test)

Question 15

what is a confounding variable

Answer 15

• when two variables are associated in such a way that their effects on a response variable cannot be distinguished from each other
  (ex. as the sales of ice cream go up so do murder rates confounding variable: temperature)

Question 16

what are the 3 principles of experimental design

Answer 16

1. control: for lurking variables
2. random assignment: using chance to assign experimental units treatments
3. replication: use enough experimental units

Question 17

what does double blind mean

Answer 17

neither the subject or person conducting the experiment knows who is receiving what treatment

Question 18

what does statistically significant mean

Answer 18

an observed effect so large that it would rarely occur by chance

Question 19

what is a block

Answer 19

group of experimental units known before the experiments to be similar in some way that is expected to affect the response (ex. gender)

Question 20

what is a matched pairs design

Answer 20

each experimental unit receives both treatments

Question 21

what is a matched pairs design

Answer 21

each experimental unit receives both treatments

Question 22

what are continuous variables

Answer 22

interval number

Question 23

what are discrete variables

Answer 23

decimals

Question 24

what are discrete variables

Answer 24

decimals