Stratified Random and Cluster Sampling

Clusters

Smaller subgroups of the population, not necessarily similar in any way besides all being together in one place, making the individuals easier to sample together.

Stratified random sampling

a method where the population is subdivided into groups called strata

Which of these statements best explains cluster sampling? a.)The cluster sampling method is a combination of random sampling techniques. b.)In the cluster sampling method, population is broken into groups and then elements are randomly selected in proportion from each group. c.)In the cluster sampling method, elements are randomly selected from the total population. d.)In the cluster sampling method, total population is roughly divided into groups based on location and a simple random sample of the groups is taken.

b.) In the cluster sampling method, population is broken into groups and then elements are randomly selected in proportion from each group.

Cluster Sample

A sampling method where the population is separated into groups, typically geographically, and a random selection of clusters is made. Each individual in the cluster becomes part of the sample.

Select the statement regarding cluster sampling that is FALSE. a.)Every element of the total population has an equal probability of being selected. b.)Every element of some groups is included in the sample. c.)Some of the groups are randomly selected. d.)The total population is divided into groups.

a.)Every element of the total population has an equal probability of being selected.

Which of these statements best defines a stratified random sample? a.)It is a sample in which every element has the same chance of being selected from the total population. b.)It is a sample where the population is first broken into homogenous groups and then elements are randomly selected, in proportion, from each group. c.)It is a sample where the population is divided into roughly equal groups, and then elements are randomly selected from each group. d.)It is a sample where every nth element of the population is selected in a sequence.

b.)It is a sample where the population is first broken into homogenous groups and then elements are randomly selected, in proportion, from each group.

Strata (stratum)

groups with homogeneous characteristic(s). They are separated by the characteristic that we think might affect the overall sample. This is to avoid having too many of the sample having this one characteristic that may affect the sample.