Chapter 7 Sampling

Question 1

generalizability and its other term

Answer 1

ensuring that the sample is a good representation of the pop. of interest; representativeness

Question 2

sampling error

Answer 2

extent to which characteristics of individuals selected for the sample differ from those of the population

Question 3

main component of a biased sample

Answer 3

not all members of a pop. have an equal prob. of being included

Question 4

which validity do biased samples lack?

Answer 4

external

Question 5

main component of an unbiased sample

Answer 5

all members of the pop. of interest have an equal prob of being included

Question 6

probability sampling vs non-prob sampling

Answer 6

prob: every member of pop of interest has an EQUAL AND KNOWN chance of being selected for the sample, random
non-prob: produces biased samples, not random

Question 7

5 techniques of random sampling

Answer 7

SRS
systematic
cluster
stratified
oversampling

Question 8

how is SRS characterized?

Answer 8

equality: each member of pop of interest has an equal chance of being chosen
independence: selecting 1 person doesnt affect the likelihood of selecting any other

Question 9

disadv of SRS

Answer 9

time-consuming and can be difficult

Question 10

systematic sampling

Answer 10

randomly generate a number N and select every Nth person/thing

Question 11

cluster sampling

Answer 11

pop of interest is divided into clusters (usually naturally occurring groups ex: location)

Question 12

multistage sampling

Answer 12

variation of cluster sampling: subset of a subset of clusters

Question 13

advantages of cluster

Answer 13

easier to contact participants and dont need a sample frame for entire population

Question 14

sampling frame

Answer 14

list of all members of a population

Question 15

stratified random sampling

Answer 15

divides the pop into strata/subgroups that are of interest in hopes of including participants from distinct strata

Question 16

3 steps of stratified random sampling

Answer 16

1. divide pop into strata
2. randomly select cases from each subgroup
3. add up all participants from dif strata together

Question 17

sample sizes in stratified random sampling can be of 2 types:

Answer 17

equal or proportionate

Question 18

oversampling

Answer 18

variation of stratified sampling; one or more groups is overrepresented

Question 19

when is oversampling most appropriate?

Answer 19

when the distribution of subgroups isnt really equal

Question 20

random sampling

Answer 20

using a random method to create a sample so each member of the pop of interest has an equal chance of being selected

Question 21

random assignment

Answer 21

used in experiments to assign participants to groups at random

Question 22

random sampling increases which validity?

Answer 22

external

Question 23

random assignment increases which validity?

Answer 23

internal

Question 24

random assignment helps to eliminate _______

Answer 24

confounds

Question 25

when can nonprob/ non random sampling be used?

Answer 25

when external validity is not vital to the study

Question 26

4 techniques of non random sampling

Answer 26

convenience
purposive
snowball
quota

Question 27

in non prob sampling what does the researcher know about a participant’s chances of being selected?

Answer 27

nothing

Question 28

convenience sampling

Answer 28

selecting participants who are readily available

Question 29

purposive sampling

Answer 29

researchers judge and select who they think the best participants will be

Question 30

snowball sampling

Answer 30

participants are asked to recommend others to participate

Question 31

quota sampling

Answer 31

select specified proportions of certain kinds of participants

Question 32

does sample size affect representativeness?

Answer 32

No

Question 33

what is a typical statistically valid sample size?

Answer 33

1000-2000 cases

Question 34

what quantifies sampling error?

Answer 34

margin of error of the estimate

Question 35

an increase in sample size is shown to be related to a decrease in what?

Answer 35

margin of error