Chapter 5: Sampling and Generalizability

Question 1

Population

Answer 1

The entire set or other entities to which study findings are to be generalized

Question 2

Sample

Answer 2

A subset of a population used to study the population as a whole

Question 3

Elements

Answer 3

The individual members of the population whose characteristics are to be measured

Question 4

Sampling frame

Answer 4

A list of all elements or other units containing the elements in a population

Question 5

Sampling units

Answer 5

Units listed at each stage of a multistage sampling design

Question 6

Target population

Answer 6

A set of elements larger than or different from the population sampled and to which the researcher would like to generalize findings

Question 7

Representative sample

Answer 7

A sample that “looks like” the population from which it was selected in all respects that are potentially relevant to the study. The distribution of characteristics among the elements of a representative sample is the same as the distribution of those characteristics among the total population. In an unrepresentative sample, some characteristics are overrepresented or underrepresented

Question 8

Census

Answer 8

Research in which information is obtained through responses from or information about all available members of an entire population

Question 9

Probability sampling method

Answer 9

A sampling method that relies on a random, or chance, selection method so that the probability of selection of population elements is known

Question 10

Nonprobability sampling methods

Answer 10

Sampling methods in which the probability of population elements is unknown

Question 11

Probability of selection

Answer 11

The likelihood that an element will be selected from the population for inclusion in the sample. In a census of all the elements of a population, the probability of any particular element will be selected is 1.0. If half the elements in the population are sample on a basis of chance (say, by tossing a coin), the probability of selection for each element is one half, or 0.5 As the size of the sample as a proportion of the population decreases, so does the probability of selection.

Question 12

Random sampling

Answer 12

A method of sampling that relies on a random, or chance, selection method so that every element of the sampling frame has a known probability of being selected

Question 13

Bias

Answer 13

sampling bias occurs when some population characteristics are over- or underrepresented int he sample because of particular features of the method of selecting the sample.

Question 14

Simple random sampling

Answer 14

A method of sampling in which every sample element is selected purely on the basis of chance through a random process

Question 15

Random number table

Answer 15

A table containing lists of numbers that are ordered solely on the basis of chance; it is used for drawing a random sample

Question 16

Random digit dialing (RDD)

Answer 16

The random dialing, by a machine, of numbers within designated phone prefixes, which creates a random sample for phone surveys

Question 17

Systematic random sampling

Answer 17

A method of sampling in which sample elements are selected from a list or from sequential files, with every nth element being selected after the first element is selected randomly

Question 18

Periodicity

Answer 18

A sequence of elements (in a list to be sampled) that varies in some regular, periodic pattern.

Question 19

Sampling interval

Answer 19

The number of cases between one sample case and another in a systematic random sample

Question 20

Cluster sampling

Answer 20

Sampling in which elements are selected in two or more stages, with the first stage being the random selected of naturally occurring clusters and the last stage being the random selection of elements within clusters

Question 21

Cluster

Answer 21

A naturally occurring, mixed aggregate of elements of the population

Question 22

Stratified random sampling

Answer 22

A method of sampling in which sample elements are selected separately from population strata that the researcher identifies in advance

Question 23

Proportionate stratified sampling

Answer 23

Sampling method in which elements are selected from strata in exact proportion to their representation in the population

Question 24

Disproportionate stratified sampling

Answer 24

Sampling in which elements are selected from strata in proportions different from those that appear in the population

Question 25

Availability sampling

Answer 25

Sampling in which elements are selected on the basis of convenience

Question 26

Quota sampling

Answer 26

A nonprobability sampling method in which elements are selected to ensure the sample represents certain characteristics in proportion to their prevalence in the population

Question 27

Purposive sampling

Answer 27

A nonprobability method in which elements are selected for a purpose, usually because of their unique position

Question 28

Snowball sampling

Answer 28

A method of sampling in which sample elements are selected as successive informants or interviewees identify them.