Chapter 9 Selecting the Sample & Setting (Quantitative)) Flashcards
Population
A well-defined group whose members possess specific attributes
Target Population
The group being studied
-Eligibility criteria
Inclusion Criteria
The key features of the target population that the investigators will use to answer their research question
Exclusion Criteria
Features of the potential study participants who meet the inclusion criteria but present with additional characteristics that could interfere with the success of the study or increase their risk for an unfavorable outcome
Sample
Small subset of a population
Select Sample
Representative of the population
Sampling
Process of selecting individuals for a study
Probability Sampling
“Random Sampling”
Simple Random Sample
Every subject has an equal & independent chance of being chosen
Cons of Simple Random Sampling
Can be time-consuming
More pricey
Difficult, or impossible, to obtain an accurate or complete sampling frame of every element in accessible population
Stratified Random Sampling
Selecting a sample to identify subgroups in the population that are represented in the sample
Advantages of Stratified Random Sampling
Achieves greater degrees of representation w/in population
Cluster (Multistage) Sampling
Groups, not individuals, are randomly selected
Used for convenience in:
o large populations
o populations spread over large geographic area
Systematic Sampling
Individuals or elements of the
population are selected from a list by
taking every kth individual
Each member does not have an
independent chance of inclusion
Considered random sampling if list is
randomly ordered 1st
Data collected conveniently and
efficiently
Non-probability Sampling
“Non-random Sampling”
Chance plays no role in
determination of sample
Limits ability to make
generalizations about findings
Many nursing research studies use
non-probability sampling because of
difficulties in obtaining random
access to populations
Convenience Sampling
Collection of data from subjects that are readily available or easily accessible to the researcher
Advantages of Convenience Sampling
Easy to carry out
Cost-efficient
Disadvantages of Convenience Sampling
Potential for bias
Limited ability for results to be generalized
Snowball (network) Sampling
Useful when list of individuals who share particular characteristic cannot be obtained
Researchers ask subjects to help them get in touch w/other potential subjects
Quota Sampling
Identifies the strata of the population based on specific characteristics
Quota is computed proportionally or
disproportionally to the population under study