1
Chapter 4: Gathering
Data
Read Chapter 5
1.
Population versus Sample
2.
Types of Studies:
Experimental and
Observational
3.
Comparing Experimental and
Observational Studies
Learning Objectives:
More Good Ways and Poor Ways
to Sample?
1.
Sampling Frame & Sampling Design
2.
Simple Random Sample (SRS)
3.
Random number table
4.
Margin of Error
5.
Convenience
Samples
6.
Types of Bias in Sample Surveys
What Are Good Ways and Poor
Ways to Experiment?
1.
Identify the elements of an experiment
2.
Experiments
3.
3 Components of a good experiment
4.
Blinding the Study
5.
Define Statistical Significance
6.
Generalizing Results of the Study
3 Components of a Good Experiment
Control/Comparison group: allows the
researcher to analyze the effectiveness of
the primary treatment
Randomization: eliminates possible
researcher bias, balances the comparison
groups on known as well as on lurking
variables
Replication: allows us to attribute
observed effects to the treatments rather
than ordinary variability
Even More Ways to Conduct Experimental
and Observational Studies
1.
Sample Surveys:
Other Random Sampling
Designs
2.
Types of Observational Studies:
Prospective
and Retrospective
3.
Multifactor Experiment
4.
Randomized block design
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2
Sample Surveys:
Random Sampling Designs
It is not always possible to conduct an
experiment so it is necessary to have well
designed, informative studies that
are not
experimental, e.g., sample surveys that
use randomization
Simple Random Sampling
Cluster Sampling
Stratified Random Sampling
Sample Surveys:
Cluster Random Sample
Cluster Random Sample Steps:
Divide the population into a large number of
clusters
, such as city blocks, organizations, etc.
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 '07
 VELLEMANP
 observational studies, stratified random sample

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