Business Statistics: A First Course

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Business Statistics A First Course

• Introduction Data CollectionChapter 1

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What Is Statistics?

• 1. Collecting Data
• e.g. Survey
• 2. Presenting Data
• e.g., Charts Tables
• 3. Characterizing Data
• e.g., Average

3
Statistical Methods
Statistical
Methods
Descriptive
Inferential
Statistics
Statistics
4
Descriptive Statistics

• 1. Involves
• Collecting Data
• Presenting Data
• Characterizing Data
• 2. Purpose
• Describe Data

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0
Q1
Q2
Q3
Q4
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Inferential Statistics

• 1. Involves
• Estimation
• Hypothesis testing
• 2. Purpose
• Make Decisions About Population Characteristics

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Key Terms

• 1. Population (Universe)
• All Items of Interest
• 2. Sample
• Portion of Population
• 3. Parameter
• Summary Measure about Population
• 4. Statistic
• Summary Measure about Sample

• P in Population Parameter
• S in Sample Statistic

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Why Collect Data?

• 1. Obtain Input to a Research Study
• 2. Measure Performance
• 3. Assist in Formulating Decision Alternatives
• 4. Satisfy Curiosity
• Knowledge for the Sake of Knowledge

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Data Sources
Data
Sources
Primary
Secondary
Published
Survey
Experiment
Observation
( On-Line)
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Data Types
Data
Numerical
Categorical
(Quantitative)
(Qualitative)
Discrete
Continuous
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Data Type Examples

• 1. Numerical
• Discrete
• To How Many Magazines Do You Subscribe Currently?
  ___ (Number)
• Continuous
• How Tall Are You? ___ (Inches)
• 2. Categorical
• Do You Own Savings Bonds? __ Yes __ No

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How Are Data Measured?

• 3. Interval Scale
• Equal Intervals
• No True 0
• e.g., Degrees Celsius
• Measurement
• 4. Ratio Scale
• Equal Intervals
• True 0
• Meaningful Ratios
• e.g., Height in Inches

• 1. Nominal Scale
• Categories
• e.g., Male-Female
• Count
• 2. Ordinal Scale
• Categories
• Ordering Implied
• e.g., High-Low
• Count

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Survey Steps

• 1. Define Purpose
• 2. Design Questionnaire
• 3. Select Sample Design
• Sample Type
• Sample Size

• Collect Data
• (Field Work)
• 5. Prepare Data
• Edit
• Code
• 6. Analyze Data
• 7. Interpret Findings
• 8. Report Results

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Why Sample?

• Cost vs. Reliability of Results
• 1. Destruction of Test Units
• Quality Control
• 2. Accurate Reliable Results
• 3. Pragmatic Reasons
• Time
• Cost

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Types of Samples
Type of
Sample
Non
Probability
Probability
Simple
Stratified
Systematic
Cluster
Random
Judge-
Chunk
Quota
ment
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Simple Random Sample

• 1. Each Population Element Has an Equal Chance
  of Being Selected
• 2. Selecting 1 Subject Does Not Affect Selecting
  Others
• 3. May Use Random Number Table, Lottery, Fish
  Bowl

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Types of Samples
Type of
Sample
Non
Probability
Probability
Simple
Stratified
Systematic
Cluster
Random
Judge-
Chunk
Quota
ment
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Systematic Sample

• 1. Every kth Element Is Selected After a Random
  Start within the First k Elements
• 2. Skip Interval, k, is Population Size
  Sample Size
• 3. Used in Telephone Surveys

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Types of Samples
Type of
Sample
Non
Probability
Probability
Simple
Stratified
Systematic
Cluster
Random
Judge-
Chunk
Quota
ment
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Stratified Sample
All Students

• 1. Divide Population into Subgroups
• Mutually Exclusive
• Exhaustive
• At Least 1 Common Characteristic of Interest
• 2. Select Simple Random Samples from Subgroups

Commuters
Residents
Sample
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Types of Samples
Type of
Sample
Non
Probability
Probability
Simple
Stratified
Systematic
Cluster
Random
Judge-
Chunk
Quota
ment
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Cluster Sample

• 1. Divide Population into Clusters
• If Consumers are Elements then Zip Codes are
  Clusters
• 2. Select Clusters Randomly
• 3. Survey All or a Random Sample of Elements in
  Cluster

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Types of Samples
Type of
Sample
Non
Probability
Probability
Simple
Stratified
Systematic
Cluster
Random
Judge-
Chunk
Quota
ment
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Nonprobability Samples

• 1. Judgment
• Use Experience to Select Sample, e.g., Test
  Markets
• 2. Quota
• Similar to Stratified Sampling Except No Random
  Sampling
• 3. Chunk (Convenience)
• Use Elements Most Available

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Errors Due to Sampling
Coverage (Frame) Error
Sampling Error
Nonresponse
Measurement Error
Sample Frame
Total Population
Planned Sample
Actual
(Students in
(Students)
(Selected Students)
Sample
Phone Book)