sampling - probability and non probability

Question 1

convenience sampling

Answer 1

-non prob
-Sampling from people who are conveniently available, happen to be there
-Respondents selected because they are convenient and accessible
-Great potential to provide unreliable and biased information
Should only be used when absolutely no need to generalize

Question 2

judgement sampling

Answer 2

-non prob
-Interviewer selects who should be part of the sample
-Individuals selected based on an expert’s opinion of who might be best to interview
-Confidence in results direct reflection of confidence in expert’s judgment
Approaches include:
-Extreme or deviant cases
-Typical cases
-Highly intense or passionate cases
Confirming or disconfirming cases

Question 3

quota sampling

Answer 3

-non prob
-Want to make sure we have x number of people from y different groups
-Extended form of judgment sampling
-Attempts to ensure that demographic or other characteristics of interest are sufficiently represented in final sample

Question 4

snowball sampling

Answer 4

-non prob
-Use first round of respondents to find subsequent respondents
-Current study participants are used to recruit new respondents
-Typically used for very small, hard to reach or highly specialized populations

Question 5

simple random sampling

Answer 5

-prob
-Have a sampling frame, use random number generator to do actual simple random sampling

Question 6

systematic sampling

Answer 6

-prob
-Version of simple random, choose a random start point on sampling frame and then every nth name there after

Question 7

stratified sampling

Answer 7

-prob
-Like quota sampling, but RANDOM, break up our population into mutually exclusive groups, then randomly sample within each stratum
-Used in situations in which it is believed there is a large variation due to observable respondent characteristics
Four steps:
-Determine classification criteria that define strata
-Each element/individual is assigned to only one strata
-Determine total sample size
-Select independent random samples from each strata

Question 8

cluster sampling

Answer 8

-prob
-Maybe we can’t get a sampling frame, randomly sampling groups or clusters of population elements
-Randomly sample groups of people rather than individuals

Question 9

Can only generalize with a ______ sample

Answer 9

PROBABILITY