Description
Describe why you were to chose a specific method to select a sample over other methods. Defend the method you preferred.
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Chapter 12
Sampling in Quantitative
Research
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Tell whether the following statement is true or false:
The aggregate of cases in which a researcher is
interested is called a sample.
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
False
The aggregate of cases in which a researcher is
interested is called a population. A sample is
selection of a portion of the population to represent
the entire population.
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Basic Sampling Concepts in Quantitative
Studies
Population: the aggregate of cases in which a
researcher is interested
Sampling: selection of a portion of the population (a
sample) to represent the entire population
Element: basic population unit about which
information is collected
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Eligibility Criteria
• Establish population characteristics
• Determine participation in study
• Maximize construct validity
• Inclusion
• Exclusion
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Question
Tell whether the following statement is true or false:
Researchers usually sample from the target
population.
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
False
Researchers usually sample from the accessible
population but should identify the target population
to which they want to generalize their results.
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Basic Sampling Concepts in Quantitative
Studies
Representative sample
A sample whose key characteristics closely
approximate those of the population
Sampling bias
The systematic over- or underrepresentation of
segments of the population on key variables
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Tell whether the following statement is true or false:
Probability sampling involves random selection of
elements.
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
True
Probability sampling involves random selection of
elements.
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Basic Sampling Concepts in Quantitative
Studies (cont.)
Probability sampling
Involves random selection of elements
Nonprobability sampling
Does not involve selection of elements at random
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Nonprobability Sampling
• Convenience sampling
• Snowball sampling
• Quota sampling
• Consecutive sampling
• Purposive sampling
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Probability Sampling
• Simple random sampling
• Stratified random sampling
• Multistage sampling
• Cluster sampling
• Systematic sampling
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Power Analysis
• Estimate sample size
• Large samples preferred to small samples
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Chapter 11
Specific Types of
Quantitative Research
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Tell whether the following statement is true or false:
Phase I clinical trials involve seeking opportunities for
refinements and preliminary evidence of efficacy.
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
False
Phase II clinical trials involve seeking opportunities for
refinements and preliminary evidence of efficacy.
Phase I features of the intervention that are
finalized.
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Clinical Trials
• Effectiveness of clinical interventions
• Phase I
• Phase II
• Phase III
• Phase IV
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Sequential Clinical Trial
• Data from paired “mini-experiments”
• Continuously analyzed
• Preference measures
• Stopping rules
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Question
Tell whether the following statement is true or false:
Practical clinical trials aim to reduce the gap between
efficacy and effectiveness studies.
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
False
Practical clinical trials are designed to provide
information to clinical decision makers.
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Practical Clinical Trials
• Also called pragmatic clinical trials
• Provide information to clinical decision makers
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Evaluation Research
• Effectiveness of a program, policy, procedure
• Assist decision makers
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Question
What is the purpose of an outcome analysis?
A. Describes the status of some condition after the
introduction of a program
B. Tests whether a program causes net impacts
C. Describes the process by which a program gets
implemented and functions in practice
D. Assesses whether the monetary costs of a program
are outweighed by benefits
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
A
Outcome analysis describes the status of some
condition after the introduction of a program.
Impact analysis tests whether a program causes net
impacts.
Process analysis describes the process by which a
program gets implemented and functions in
practice.
Cost analysis assesses whether the monetary costs of
a program are outweighed by benefits.
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Various Analyses
• Process or implementation
• Outcome
• Impact
• Cost or economic
– Cost–benefit analysis
– Cost-effectiveness analysis
– Cost-utility analysis
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Tell whether the following statement is true or false:
Outcome research examines the quality and
effectiveness of health care and nursing services.
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
True
Outcome research examines the quality and
effectiveness of health care and nursing services.
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Outcome Research
• Quality and effectiveness of health care and nursing
services
• Health care quality
– Structure
– Process
– Client risk factors
– Outcomes
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Survey Research
• People’s characteristics, behaviors, and intentions
by asking them to answer questions
• Personal interviews
• Telephone interviews
• Questionnaires
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Secondary Analysis
• Researchers analyze previously collected data.
• Economical
• Difficult to identify appropriate existing data base
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Needs Assessment
• Needs of group or community
• Three main needs
– Key informant
– Survey
– Indicators approach
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Question
Tell whether the following statement is true or false:
The Delphi technique is a method of problem solving
in which one round of questionnaires are sent to a
panel of experts.
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
False
The Delphi technique is a method of problem solving
in which several rounds of questionnaires are sent
to a panel of experts, not one round.
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Delphi Technique
• Problem solving
• Several rounds of questionnaires
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Replication Studies
• Identical
• Virtual
• Systematic extension replication
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Methodologic Studies
• Development
• Validation
• Assessment
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Chapter 13
Sampling in Quantitative
Research
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question #1
❖Tell whether the following statement is true or false:
❖The aggregate of cases in which a researcher is
interested is called a sample.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer to Question #1
❖False
❖The aggregate of cases in which a researcher is
interested is called a population. A sample is
selection of a portion of the population to represent
the entire population.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Basic Sampling Concepts in Quantitative
Studies #1
❖Population: the aggregate of cases in which a
researcher is interested
❖Accessible population: the aggregate of cases
that conform to designated criteria and that are
accessible for a study
❖Target population: the aggregate of cases about
which the researcher would like to generalize
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Basic Sampling Concepts in Quantitative
Studies #2
❖Eligibility criteria/inclusive criteria: criteria that
specify population characteristics
oCost
oPractical constraints
oPeople’s ability to participate
oDesign considerations
❖Exclusion criteria
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Basic Sampling Concepts in Quantitative
Studies #3
❖Samples and Sampling
❖Sampling: selection of a portion of the population
(a sample) to represent the entire population
❖Element: basic population unit about which
information is collected
❖Sample: a subset of population elements
oRepresentative sample
oProbability sample
oNonprobability sample
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question #2
❖Tell whether the following statement is true or false:
❖Researchers usually sample from the target
population.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer to Question #2
❖False
❖Researchers usually sample from the accessible
population but should identify the target population
to which they want to generalize their results.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Basic Sampling Concepts in Quantitative
Studies #4
❖Staged sample: samples are sometimes selected in
multiple phases
❖Sampling bias: the systematic over- or
underrepresentation of segments of the population
on key variables
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question #3
❖Tell whether the following statement is true or false:
❖Probability sampling involves random selection of
elements.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer to Question #3
❖True
❖Probability sampling involves random selection of
elements.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Nonprobability Sampling
o Convenience sampling
o Snowball sampling
o Quota sampling
o Consecutive sampling
o Purposive sampling
❖Evaluation of nonprobability sampling
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Probability Sampling
o Simple random sampling
o Stratified random sampling
o Multistage sampling
o Cluster sampling
o Systematic sampling
❖Evaluation of probability sampling
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Sample Size in Quantitative Studies
❖Power analysis
o Estimate sample size
o Large samples preferred to small samples
❖Sample size basics
❖Factors affecting sample size /requirements in
quantitative research
o Effect size
o Homogeneity of the population
o Cooperation and attrition
o Subgroup analyses
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Implementing a Quantitative Sampling Plan
❖Steps in sampling
o Identify the population
o Specify the eligibility criteria
o Specify the sampling plan
o Recruit the sample
❖Sample recruitment
o Screening instrument
❖Generalizing from samples
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Critical Appraisal of Sampling Plans #1
❖Sampling Plan
o Construct
o Internal factors
o External factors
o Statistical conclusion validity
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Critical Appraisal of Sampling Plans #2
❖Sampling plan should be scrutinized with respect to
o Approach used
o Study population and eligibility criteria
o Number of participants and rationale for sample
size
o Inclusion of power analysis
o Description of main characteristics of sample
o Number and characteristics of participants who
declined participation/dropped out
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