Knowledge Check #2
(Ch.9) Populations, samples, probability, and non-probability sampling methods,
setting
Sample – selected group of people (or elements)
Sampling – selecting a group of people, events, objects, or other elements with
which to conduct a study.
Populations – particular group of individuals or elements who are the focus of the
research. (E.g. people with type 2 diabetes).
o Target Population – the entire set of individuals or elements who meet the
sampling criteria. (E.g. female, 18 years or older, not on insulin, etc.).
o Accessible Population – portion of the target population to which the
researcher has reasonable access. Might include elements within a country,
state, city, hospital, nursing unit. (E.g. Individuals with diabetes who were
provided care in a primary care clinic in Arlington, TX).
Elements – person, event, object, or any other single unit of study (the individual
units of the population and sample)
Random Sampling – each person or element in the population has an opportunity
to be selected for the sample. Chosen at random.
Sampling frame – a list of every member of the population, using the sampling
criteria to define eligibility.
Probability Sampling – each person or element in a population has an opportunity
to be selected for a sample, which is achieved through random sampling. Increase
sample’s representativeness of target population.
, o Simple Random – most basic of probability sampling. Randomly selects
elements from the sampling frame.
o Stratified Random – used in situations in which the researcher knows some
of the variables in the population that are critical for achieving
representativeness. Variables commonly used are age, gender, race and
ethnicity, socioeconomic status, diagnosis, geographic region, type of
institution, type of care, type of registered nurse, etc. Stratification ensures
that all levels of the identified variables are adequately represented in the
sample.
o Cluster sampling – Used to obtain a geographically dispersed sample or
because the researcher cannot identify the individual elements making up the
population and therefore cannot develop a sampling frame.
o Systematic sampling – used when an ordered list of all members of the
population is available. Process involves selecting every nth individual on the
list, using a starting point selected randomly.
Nonprobability sampling – not every element of a population has an opportunity
to be selected for a study sample. Commonly used in nursing studies because of the
limited number of patients available for research.
o Convenience sampling – also known as accidental sampling, is a weak
approach because it provides little opportunity to control for biases; subjects
are included in the study merely because they happen to be in the right place
at the right time.
o Quota sampling – convenience sampling + inclusion of subject types likely
to be underrepresented in the convenience sample. (females, minority groups,
older adults, and the poor, rich, and undereducated).
o Purposeful or Purposive sampling – also known as “judgmental” or
“selective” sampling. The researcher consciously selects certain participants,
elements, events, or incidents to include in the study.
o Network sampling – also known as “snowball,” “chain,” or “nominated”
sampling. Holds promise for locating participants who would be difficult or
impossible to obtain in other ways or who have not been previously identified
for study. (E.g dependent on alcohol, abuse children, commit sexual offenses,
are addicted to drugs, or commit criminal acts). These persons are seldom
willing to make themselves known.
o Theoretical sampling – used in qualitative research to develop a selected
theory through the research process. Used most frequently with grounded
theory research because the focus of this type of research is theory
development.
Research Setting – site or location used to conduct a study. 3 common settings for
conducting nursing studies are natural, partially controlled, and highly controlled.
o Natural/Field setting – uncontrolled, real-life situation or environment.
Conducting a study in this setting means that the researcher does NOT
manipulate or change the environment for the study.
o Partially controlled setting – environment that is manipulated or modified
in some way by the researcher.
o Highly controlled setting – an artificially constructed environment
developed for the sole purpose of conducting research. Reduces influence of
extraneous variables, which enables researchers to examine the effects of
independent variables on dependent variables accurately.
Levels of Measurement, measurement error, reliability and validity.
(Ch.9) Populations, samples, probability, and non-probability sampling methods,
setting
Sample – selected group of people (or elements)
Sampling – selecting a group of people, events, objects, or other elements with
which to conduct a study.
Populations – particular group of individuals or elements who are the focus of the
research. (E.g. people with type 2 diabetes).
o Target Population – the entire set of individuals or elements who meet the
sampling criteria. (E.g. female, 18 years or older, not on insulin, etc.).
o Accessible Population – portion of the target population to which the
researcher has reasonable access. Might include elements within a country,
state, city, hospital, nursing unit. (E.g. Individuals with diabetes who were
provided care in a primary care clinic in Arlington, TX).
Elements – person, event, object, or any other single unit of study (the individual
units of the population and sample)
Random Sampling – each person or element in the population has an opportunity
to be selected for the sample. Chosen at random.
Sampling frame – a list of every member of the population, using the sampling
criteria to define eligibility.
Probability Sampling – each person or element in a population has an opportunity
to be selected for a sample, which is achieved through random sampling. Increase
sample’s representativeness of target population.
, o Simple Random – most basic of probability sampling. Randomly selects
elements from the sampling frame.
o Stratified Random – used in situations in which the researcher knows some
of the variables in the population that are critical for achieving
representativeness. Variables commonly used are age, gender, race and
ethnicity, socioeconomic status, diagnosis, geographic region, type of
institution, type of care, type of registered nurse, etc. Stratification ensures
that all levels of the identified variables are adequately represented in the
sample.
o Cluster sampling – Used to obtain a geographically dispersed sample or
because the researcher cannot identify the individual elements making up the
population and therefore cannot develop a sampling frame.
o Systematic sampling – used when an ordered list of all members of the
population is available. Process involves selecting every nth individual on the
list, using a starting point selected randomly.
Nonprobability sampling – not every element of a population has an opportunity
to be selected for a study sample. Commonly used in nursing studies because of the
limited number of patients available for research.
o Convenience sampling – also known as accidental sampling, is a weak
approach because it provides little opportunity to control for biases; subjects
are included in the study merely because they happen to be in the right place
at the right time.
o Quota sampling – convenience sampling + inclusion of subject types likely
to be underrepresented in the convenience sample. (females, minority groups,
older adults, and the poor, rich, and undereducated).
o Purposeful or Purposive sampling – also known as “judgmental” or
“selective” sampling. The researcher consciously selects certain participants,
elements, events, or incidents to include in the study.
o Network sampling – also known as “snowball,” “chain,” or “nominated”
sampling. Holds promise for locating participants who would be difficult or
impossible to obtain in other ways or who have not been previously identified
for study. (E.g dependent on alcohol, abuse children, commit sexual offenses,
are addicted to drugs, or commit criminal acts). These persons are seldom
willing to make themselves known.
o Theoretical sampling – used in qualitative research to develop a selected
theory through the research process. Used most frequently with grounded
theory research because the focus of this type of research is theory
development.
Research Setting – site or location used to conduct a study. 3 common settings for
conducting nursing studies are natural, partially controlled, and highly controlled.
o Natural/Field setting – uncontrolled, real-life situation or environment.
Conducting a study in this setting means that the researcher does NOT
manipulate or change the environment for the study.
o Partially controlled setting – environment that is manipulated or modified
in some way by the researcher.
o Highly controlled setting – an artificially constructed environment
developed for the sole purpose of conducting research. Reduces influence of
extraneous variables, which enables researchers to examine the effects of
independent variables on dependent variables accurately.
Levels of Measurement, measurement error, reliability and validity.
