Lecture 5B, part 2

Question 1

Details about sampling frames

Answer 1

Samples should be representative, and the sampled pop should contain the same variation as the pop that it is selected from (otherwise selection bias can result)
Properly drawn sample provides info appropriate for describing the pop composing the sampling frame
Sample is only representative of the pop that it is selected from

Question 2

Aspects of probability sampling

Answer 2

Each element/unit has an equal chance of being selected in the sample independent of any other event in the selection process
Can assign a numeric value to the probability of any one person being chosen for the study/requires that the number of potential participants in the study pop must be known

Question 3

Advantages of probability sampling

Answer 3

Although never perfectly representative, more likely to avoid the problem of selection bias
Permits estimates of accuracy or representativeness

Question 4

Aspects of non-probability sampling

Answer 4

Each element may have an unequal or unknown chance of being selected in the sample (the probability of selection is unknown)
Used when no sampling frame is available

Question 5

Types of probability sampling methods

Answer 5

Simple random
Systematic random
Stratified random
Cluster
Multi-stage

Question 6

Definition of simple random sampling

Answer 6

Every individual in the sampling frame has the same probability of being selected for the sample

Question 7

Sampling ratio definition

Answer 7

Proportion of elements in the pop that are being selected

Question 8

When is systematic random sampling used?

Answer 8

When simple random sampling may not be efficient or too laborious

Question 9

What does systematic random sampling require?

Answer 9

A list, where every kth element in the total list is chosen (systematically) for inclusion in the sample

Question 10

Sampling interval defintiion

Answer 10

Standard distance between elements selected in the sample

Question 11

Disadvantage of systematic random sampling?

Answer 11

Since it requires a list, representativeness depends on the random arrangement of the subjects
Selection bias results if list is subject to periodicity (such as a cyclical pattern)

Question 12

How can bias be avoided with systematic random sampling?

Answer 12

The first person should be selected at random

Question 13

When is stratified random sampling used?

Answer 13

When researchers want to assign a greater than random probability of selecting units with particular characteristics (also called over-sampling)

Question 14

What does stratified random sampling ensure?

Answer 14

Appropriate numbers of elements are drawn from homogenous subjects of the pop

Question 15

How many characteristics can be used in stratified random sampling?

Answer 15

More than one

Question 16

When is cluster sampling used?

Answer 16

When impossible or impractical to compile an exhaustive list of all the elements composing the target pop

Question 17

How is cluster sampling done?

Answer 17

Target pop is divided into naturally formed clusters, some of which are selected randomly
Involves the repetition of two basic steps: listing and sampling
-List of primary sampling units is compiled and a sample is selected from within

Question 18

What can be used in multi-stage sampling?

Answer 18

Random sampling methods in combination through two or more stages of sampling

Question 19

What is ideal in terms of its ability to minimize sampling or selection bias?

Answer 19

Simple random sampling

Question 20

Multi-stage sampling is more subject to what with each additional step/stage?

Answer 20

Sampling error

Question 21

What are the types of non-probability sampling methods?

Answer 21

Convenience
Purposive
Quota
Snowball
Respondent-driven

Question 22

Definition of convenience sampling

Answer 22

Selecting a sample from the ppl who are conveniently and readily available (not selected from a sampling frame with any measurable representativeness)

Question 23

Characteristics of convenience sampling

Answer 23

Very limited generalizability
Little known about the relevant characteristics of the target or study pop

Question 24

Definition of purposive sampling

Answer 24

Subjects selected on the basis of researchers’ knowledge and the purpose of the study

Question 25

What is the most common type of non-probability sampling?

Answer 25

Purposive