CHAPTER 4:
Data Collection
and Sampling Methods
to accompany
Introduction to Business Statistics
fourth edition,by Ronald M,Weiers
Presentation by Priscilla Chaffe-Stengel
Donald N,Stengel
? 2002 The Wadsworth Group
Chapter 4 - Learning Objectives
? Describe the types of studies and their purposes:
– Exploratory
– Descriptive
– Causal
– Predictive
? Explain the differences between data sources:
– Primary
– Secondary,Internal versus External
? Differentiate between sampling designs:
– Probabilitistic versus nonprobabilitistic designs
? Differentiate between sampling and nonsampling
errors,? 2002 The Wadsworth Group
Chapter 4 - Key Terms
? Error
– Sampling
– Nonsampling
? Types of Studies
– Exploratory
– Descriptive
– Causal
– Predictive
? Types of Data
– Primary
– Secondary
? Internal vs External
? Probability sample
– Simple random sample
– Systematic sample
– Stratified sample
– Cluster sample
? Nonprobability sample
– Convenience sample
– Quota sample
– Purposive sample
– Judgment sample
? 2002 The Wadsworth Group
Types of Studies
? Exploratory
– Understand a problem,identify relevant
variables,formulate hypotheses
? Descriptive
– Establish reliable measurements
? Causal
– Determine relationships among variables
? Predictive
– Use analysis to forecast
? 2002 The Wadsworth Group
Sources of Data
? Primary
– Data generated by the researcher for this study
– Survey,experimental,observational research most
popular
– Tend to require more time and expense than
secondary data
? Secondary
– Data gathered from another source or for another
purpose
?Internal sources within the researcher’s
organization
?External sources,including governmental,trade,
commercial and internet sources
? 2002 The Wadsworth Group
Types and Sources of Error
? Sampling Error
– Random,nondirectional
– When a sample is used instead of a census
? Nonsampling Error
– Directional bias overstating or understating
the true population parameter
– Potential sources:
?Poor sample design
?Poor measurement
?Poor instrumentation
? 2002 The Wadsworth Group
Types of Samples
? Simple random
? Systematic
? Every person has an equal
chance of being selected,
Best when roster of the
population exists.
? Randomly enter a stream of
elements and sample every
kth element,Best when
elements are randomly
ordered,no cyclic variation.
Probability,or Scientific,Samples,Each element to be
sampled has a known (or calculable) chance of being selected,
? 2002 The Wadsworth Group
Types of Samples
? Stratified
? Cluster
? Randomly sample elements
from every layer,or
stratum,of the population,
Best when elements within
strata are homogeneous.
? Randomly sample elements
within some of the strata,
Best when elements within
strata are heterogeneous.
Probability,or Scientific,Samples,Each element to be
sampled has a known (or calculable) chance of being selected,
? 2002 The Wadsworth Group
Types of Samples
? Convenience
? Quota
? Elements are sampled
because of ease and
availability.
? Elements are sampled,but
not randomly,from every
layer,or stratum,of the
population.
Nonprobability Samples,Not every element has a chance to
be sampled,Selection process usually involves subjectivity.
? 2002 The Wadsworth Group
Types of Samples
? Purposive
? Judgment
? Elements are sampled
because they are atypical,
not representative of the
population.
? Elements are sampled
because the researcher
believes the members are
representative of the
population.
Nonprobability Samples,Not every element has a chance to
be sampled,Selection process usually involves subjectivity.
? 2002 The Wadsworth Group
Example,Types of Data
Problem 4.46
? The Sonic Travel Agency has not kept
pace with the current boom in family
vacation air travel between the agency’s
northern city and sunny Florida,For
each of the following,indicate whether
they are primary or secondary,If
secondary,further indicate whether
they are internal or external.
? 2002 The Wadsworth Group
Problem 4.46
? a) Sonic’s research
department conducts
a survey of past
customers to
determine their level
of satisfaction with
the agency’s service
? a) Primary data
– The data were generated
by the researcher to study
this problem.
? 2002 The Wadsworth Group
Problem 4.46,continued
? b) The Florida
Bureau of Tourism
sends travel
agencies across the
nation the results of
a study describing
the characteristics of
winter vacationers
to the state,
including where and
how long people
intended to stay.
? b) Secondary data
– The data were not generated
for the purpose of examining
the question at hand.
External data
– The data were provided by an
outside agency,the Florida
Bureau of Tourism.
? 2002 The Wadsworth Group
Problem 4.46,continued
? c) To get a better
grasp of the
problem,the
president of Sonic
examines the
company’s annual
reports for the
past ten years.
? c) Secondary data
– The data were not generated
for the purpose of examining
the problem at hand.
Internal data
– The data were produced
from within the firm,so they
are internal data.
? 2002 The Wadsworth Group
Example,Types of Studies
Problem 4.48
? For each of the report titles below,
indicate whether the study involved
was exploratory,descriptive,causal,or
predictive.
? 2002 The Wadsworth Group
Problem 4.48
? a),The Popularity of
Bowling as a
Participant Sport in
Ohio.”
? b),The Effects of TV
Violence on Crime in
Small Towns.”
? a) Descriptive study
– This is probably a
descriptive study
showing the number of
people who bowl in Ohio.
? b) Causal study
– This is probably a causal
study that examines the
effect of TV violence (the
cause) on crimes in small
towns (the outcomes).
? 2002 The Wadsworth Group
Problem 4.48,continued
? c),A Preliminary
Investigation of
the Market for Pet
Foods.”
? d),Family
Vacationing in the
21st Century.”
? c) Exploratory study
– This is probably an
exploratory study that points
out relationships and
possible hypotheses for
further study.
? d) Predictive study
– This is probably a predictive
study to forecast vacationing
patterns in the 21st century.
? 2002 The Wadsworth Group
Example,Types of Errors
Problem 4.64
? Researchers at a university with an
enrollment of 12,000 take a census of the
entire student population,asking,
“Shoplifting is not only illegal,it raises
the prices that we all have to pay,Have
you ever shoplifted from the university
bookstore?” Based on this,discuss the
possible presence of a) sampling and
b) nonsampling error.
? 2002 The Wadsworth Group
Problem 4.64
? a) Sampling error not
present
? b) Nonsampling
error present
? a) Since the study
includes the entire
student population,
there will be no
sampling error present.
? b) Because the question’s
wording invites biased
responses,students may
be afraid to admit to
shoplifting,so there will
be nonsampling errors
present.
? 2002 The Wadsworth Group
Data Collection
and Sampling Methods
to accompany
Introduction to Business Statistics
fourth edition,by Ronald M,Weiers
Presentation by Priscilla Chaffe-Stengel
Donald N,Stengel
? 2002 The Wadsworth Group
Chapter 4 - Learning Objectives
? Describe the types of studies and their purposes:
– Exploratory
– Descriptive
– Causal
– Predictive
? Explain the differences between data sources:
– Primary
– Secondary,Internal versus External
? Differentiate between sampling designs:
– Probabilitistic versus nonprobabilitistic designs
? Differentiate between sampling and nonsampling
errors,? 2002 The Wadsworth Group
Chapter 4 - Key Terms
? Error
– Sampling
– Nonsampling
? Types of Studies
– Exploratory
– Descriptive
– Causal
– Predictive
? Types of Data
– Primary
– Secondary
? Internal vs External
? Probability sample
– Simple random sample
– Systematic sample
– Stratified sample
– Cluster sample
? Nonprobability sample
– Convenience sample
– Quota sample
– Purposive sample
– Judgment sample
? 2002 The Wadsworth Group
Types of Studies
? Exploratory
– Understand a problem,identify relevant
variables,formulate hypotheses
? Descriptive
– Establish reliable measurements
? Causal
– Determine relationships among variables
? Predictive
– Use analysis to forecast
? 2002 The Wadsworth Group
Sources of Data
? Primary
– Data generated by the researcher for this study
– Survey,experimental,observational research most
popular
– Tend to require more time and expense than
secondary data
? Secondary
– Data gathered from another source or for another
purpose
?Internal sources within the researcher’s
organization
?External sources,including governmental,trade,
commercial and internet sources
? 2002 The Wadsworth Group
Types and Sources of Error
? Sampling Error
– Random,nondirectional
– When a sample is used instead of a census
? Nonsampling Error
– Directional bias overstating or understating
the true population parameter
– Potential sources:
?Poor sample design
?Poor measurement
?Poor instrumentation
? 2002 The Wadsworth Group
Types of Samples
? Simple random
? Systematic
? Every person has an equal
chance of being selected,
Best when roster of the
population exists.
? Randomly enter a stream of
elements and sample every
kth element,Best when
elements are randomly
ordered,no cyclic variation.
Probability,or Scientific,Samples,Each element to be
sampled has a known (or calculable) chance of being selected,
? 2002 The Wadsworth Group
Types of Samples
? Stratified
? Cluster
? Randomly sample elements
from every layer,or
stratum,of the population,
Best when elements within
strata are homogeneous.
? Randomly sample elements
within some of the strata,
Best when elements within
strata are heterogeneous.
Probability,or Scientific,Samples,Each element to be
sampled has a known (or calculable) chance of being selected,
? 2002 The Wadsworth Group
Types of Samples
? Convenience
? Quota
? Elements are sampled
because of ease and
availability.
? Elements are sampled,but
not randomly,from every
layer,or stratum,of the
population.
Nonprobability Samples,Not every element has a chance to
be sampled,Selection process usually involves subjectivity.
? 2002 The Wadsworth Group
Types of Samples
? Purposive
? Judgment
? Elements are sampled
because they are atypical,
not representative of the
population.
? Elements are sampled
because the researcher
believes the members are
representative of the
population.
Nonprobability Samples,Not every element has a chance to
be sampled,Selection process usually involves subjectivity.
? 2002 The Wadsworth Group
Example,Types of Data
Problem 4.46
? The Sonic Travel Agency has not kept
pace with the current boom in family
vacation air travel between the agency’s
northern city and sunny Florida,For
each of the following,indicate whether
they are primary or secondary,If
secondary,further indicate whether
they are internal or external.
? 2002 The Wadsworth Group
Problem 4.46
? a) Sonic’s research
department conducts
a survey of past
customers to
determine their level
of satisfaction with
the agency’s service
? a) Primary data
– The data were generated
by the researcher to study
this problem.
? 2002 The Wadsworth Group
Problem 4.46,continued
? b) The Florida
Bureau of Tourism
sends travel
agencies across the
nation the results of
a study describing
the characteristics of
winter vacationers
to the state,
including where and
how long people
intended to stay.
? b) Secondary data
– The data were not generated
for the purpose of examining
the question at hand.
External data
– The data were provided by an
outside agency,the Florida
Bureau of Tourism.
? 2002 The Wadsworth Group
Problem 4.46,continued
? c) To get a better
grasp of the
problem,the
president of Sonic
examines the
company’s annual
reports for the
past ten years.
? c) Secondary data
– The data were not generated
for the purpose of examining
the problem at hand.
Internal data
– The data were produced
from within the firm,so they
are internal data.
? 2002 The Wadsworth Group
Example,Types of Studies
Problem 4.48
? For each of the report titles below,
indicate whether the study involved
was exploratory,descriptive,causal,or
predictive.
? 2002 The Wadsworth Group
Problem 4.48
? a),The Popularity of
Bowling as a
Participant Sport in
Ohio.”
? b),The Effects of TV
Violence on Crime in
Small Towns.”
? a) Descriptive study
– This is probably a
descriptive study
showing the number of
people who bowl in Ohio.
? b) Causal study
– This is probably a causal
study that examines the
effect of TV violence (the
cause) on crimes in small
towns (the outcomes).
? 2002 The Wadsworth Group
Problem 4.48,continued
? c),A Preliminary
Investigation of
the Market for Pet
Foods.”
? d),Family
Vacationing in the
21st Century.”
? c) Exploratory study
– This is probably an
exploratory study that points
out relationships and
possible hypotheses for
further study.
? d) Predictive study
– This is probably a predictive
study to forecast vacationing
patterns in the 21st century.
? 2002 The Wadsworth Group
Example,Types of Errors
Problem 4.64
? Researchers at a university with an
enrollment of 12,000 take a census of the
entire student population,asking,
“Shoplifting is not only illegal,it raises
the prices that we all have to pay,Have
you ever shoplifted from the university
bookstore?” Based on this,discuss the
possible presence of a) sampling and
b) nonsampling error.
? 2002 The Wadsworth Group
Problem 4.64
? a) Sampling error not
present
? b) Nonsampling
error present
? a) Since the study
includes the entire
student population,
there will be no
sampling error present.
? b) Because the question’s
wording invites biased
responses,students may
be afraid to admit to
shoplifting,so there will
be nonsampling errors
present.
? 2002 The Wadsworth Group
