ch 9 populations and samples Flashcards
Selecting a group of people, events,
behaviors, or other elements with which to
conduct a study
sampling
sampling method, defines selection process
sampling plan
defines selected group of people/elements from which data are collected for a
study
sample
particular group of individuals
or elements who are the focus of the research
population
entire set of individuals
or elements who meet the sampling criteria
target population
portion of the target population to which the researcher has reasonable access
accessible population
Individual units of the population
and sample
elements
-Extending the findings from the sample
under study to the larger population
-The extent is influenced by the quality of the
study and consistency of the study’s
findings
generalization
Characteristics that the subject or element
must possess to be part of the target
population
inclusion (sampling criteria)
Characteristics that can cause a person or
element to be excluded from the target
population
exclusion (sampling criteria)
type of sample: As similar as possible
so as to control for extraneous variables
homogeneous sample
type of sample: Represents a broad
range of values
(used when narrow focus is not desirable)
heterogeneous sample
The sample, the accessible population, and
the target population are alike in as many
ways as possible
representativeness
things to evaluate in representativeness
-setting
-characteristics of subjects
-Distribution of values on variables measured in the study
Difference between the population mean and the mean of the sample
sampling error
type of variation: Expected difference in
values that occurs when different subjects
from same sample are examined
random variation
type of variation: Consequence of selecting subjects whose measurement values differ in some way from those of the population
systemic variation/bias
Withdrawal or loss of
subjects from a study
sample attrition
Number of subjects who
remain in and complete a study
sample retention
how to calculate sample attrition
number of subjects withdrawing ÷
number of study subjects × 100
4 types probability sampling
-simple random
-stratified random
-random cluster
-systematic
smaller groups that represent the
entire population
stratified random
type of nonprobability sampling: Convenience sampling but a
strategy to ensure inclusion of
subject types
quota sampling
type of nonprobability sampling: Researcher seeks out, based on researcher
judgment
purposive sampling
type of nonprobability sampling:
-Used in grounded theory research
-The sample is saturated when the data collection is complete based on the researchers’ expectations
theoretical sampling
Ability to detect differences in the population
or capacity to correctly reject a null
hypothesis
power analysis
