doane chapter 01
TRANSCRIPT
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Overview of Statistics
What is Statistics?Why Study Statistics?
Uses of Statistics
Statistical Challenges
Writing and Presenting Reports
Statistical Pitfalls
Statistics: An Evolving Field
Chapter
1
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What is Statistics?
Statistics is the science of collecting, organizing,
analyzing, interpreting, and presenting data.
A statisticis a single measure (number) used tosummarize a sample data set. For example, the
average height of students in this class.
A statisticianis an expert with at least a masters
degree in mathematics or statistics or a trained
professional in a related field.
McGraw-Hill/Irwin 2007 The McGraw-Hill Companies, Inc. All rights reserved.
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Why Study Statistics?
Communicat ion
Compu ter Ski lls
Understanding the language of statistics facilitates
communication and improves problem solving.
The use of spreadsheets for data analysis and word
processors or presentation software for reportsimproves upon your existing skills.
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Why Study Statistics?
Info rmat ion Management
Technical L i teracy
Statistics help summarize large amounts of data
and reveal underlying relationships.
Career opportunities are in growth industries
propelled by advanced technology. The use ofstatistical software increases your technical
literacy.
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Why Study Statistics?
Career Advancement
Quali ty Improvement
Statistical literacy can enhance your career mobility.
Statistics helps firms oversee their suppliers,
monitor their internal operations and identifyproblems.
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Uses of Statistics
Two p r imary u ses for statis t ics:
Descriptive statistics the collection, organization,
presentation and summary of data.
Inferential statistics generalizing from a sample
to a population, estimating unknown parameters,
drawing conclusions, making decisions.
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Uses of Statistics
Overview o f Stat ist ic s
Statistics
Describing
DataMaking Inferences
from Samples
Visual
Displays
Numerical
Summaries
Estimating
Parameters
Testing
Hypotheses
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Uses of Statistics
Audi t ing
Marketing
Sample from over 12,000 invoices to estimate the
proportion of incorrectly paid invoices.
Identify likely repeat customers for Amazon.comand suggests co-marketing opportunities based
on a database of 5 million Internet purchases.
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Uses of Statistics
Health Care
Purchasing
Evaluate 100 incoming patients using a 42-item
physical and mental assessment questionnaire.
Determine the defect rate of a shipment andwhether that rate has changed significantly over
time.
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Uses of Statistics
Medicine
Forecast ing
Determine whether a new drug is really better
than the placebo or if the difference is due to
chance.
Manage inventory by forecasting consumerdemand.
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Statistical Challenges
Is technically current (e.g., software-wise).
Communicates well. Is proactive.
Has a broad outlook.
Is flexible.
Focuses on the main problem.
The Ideal Statist ic ian
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Statistical Challenges
Meets deadlines.
Knows his/her limitations and is willing to ask for help.
Can deal with imperfect information.
Has professional integrity.
The Ideal Statist ic ian
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Statistical Challenges
Work ing w ith Imperfect Data
Deal ing w ith Pract ical Constraints
State any assumptions and limitations and use
generally accepted statistical tests to detect
unusual data points or to deal with missing data.
You will face constraints on the type and quantityof data you can collect.
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Statistical Challenges
Upho lding Ethical Standards
Using Consu l tants
Know and follow accepted procedures, maintain
data integrity, carry out accurate calculations,
report procedures, protect confidentiality, citesources and financial support.
Hire consultants at the beginningof the project,when your team lacks certain skills or when an
unbiased or informed view is needed.
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Statistical Challenges
Ski lls Needed fo r Success in Bus iness
Forinitial
job success
Forlong-range
job success
Most common
weaknesses
Report-writing Managerial accounting Communication skills
Accounting principles Managerial economics Writing skills
Mathematics Managerial finance Immaturity
Statistics Report writing Unrealistic expectations
Oral communication
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Writing and Presenting Reports
Rules for Power Wri t ing
Outline the report before you begin.
Complete the report in sections.
Ask trusted peers to review the report and make
any necessary revisions.
Be prepared to make multiple revisions.
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Writing and Presenting Reports
Writ ing Style
Answer research question succinctly.
List most important results first.
Include section headings and avoid lengthy
paragraphs.
Provide clear data sources.
Use appendices for technical information.
Be stylistically consistent.
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Writing and Presenting Reports
Avoid Jargon
Spel ling and Grammar
Present technical concepts so that others can
understand them.
Dont rely on software to catch all spelling and
grammar errors.
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Writing and Presenting Reports
Make it Attract ive
Descriptive title.
Date
Author(s)
Page number.
Wide margins.
Typeface and point size. Bullets and subheadings.
Bold face, italics, color.
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Writing and Presenting Reports
Organizing a Techn ical Repo rt
Typical business report style includes:
Executive Summary (1 page maximum)
- Briefly describe task and goals, data anddata sources, methods that were used,
main findings and any limitations.
Introduction (1 to 3 paragraphs)
- Statement of the problem
- Data sources and definitions
- Methods utilized
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Writing and Presenting Reports
Organizing a Techn ical Repo rt
Typical business report style includes:
Body of the Report (as long as necessary)
- Discussion, explanations, interpretations- Tables and graphs, as needed
Conclusions (1 to 3 paragraphs)
- Statement of findings (in order of importance)- Limitations (if necessary)
- Future research suggestions
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Writing and Presenting Reports
Organizing a Techn ical Repo rt
Typical business report style includes:
Bibliography and Sources
Appendices (if needed for lengthy or technical
material)
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Writing and Presenting Reports
Tables and Graphs
Embed in the narrative
near the paragraph in
which they are interpreted.
Number and title each table
above the table, each graphbelow the graph
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Writing and Presenting Reports
Rules for Present ing Oral Repo rts
Select a few key points to convey.
Use simple charts and diagrams.
Emphasize using color and fonts creatively.
Have backup slides or transparencies.
Rehearse timing. Refer audience to written report for details.
Imagine yourself in the audience.
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Writing and Presenting Reports
Pictures Help Make the Poin t
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Writing and Presenting Reports
The Three Ps
Pace yourself when presenting. Take your time,
introduce yourself, your data and your project.
Make the first minute count.
Plan what your are going to present. Organize
your ideas with an outline. Keep it simple!
Practice before presenting to get the timing right.
Consider videotaping yourself or practicing in front
of peers.
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Statistical Pitfalls
Pitfall 3: Attaching Importance to RareObservations from Large Samples
Pitfall 4: Using Poor Survey Methods
Be careful about drawing strong inferences from
events that are not surprising when looking at theentire population (e.g., winning the lottery).
Be careful about using poor sampling methods or
vaguely worded questions (e.g., anonymous
survey or quiz).
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Statistical Pitfalls
Pitfall 5: Assuming a Causal Link Based onObservations
Pitfall 6: Making Generalizations about
Individuals from Observations about Groups
Be careful about drawing conclusions when no
cause-and-effect link exists (e.g., most sharkattacks occur between 12p.m. and 2p.m.).
Avoid reading too much into statistical
generalizations (e.g., men are taller than
women).
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Statistical Pitfalls
Pitfall 7: Unconscious Bias
Pitfall 8: Attaching Practical Importance to
Every Statistically Significant Study Result
Be careful about unconsciously or subtly allowing
bias to color handling of data (e.g., heart disease
in men vs. women).
Statistically significant effects may lack practicalimportance (e.g., Austrian military recruits born in
the spring average 0.6 cm taller than those born
in the fall).
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Statistics: An Evolving Field
Statistics is a relatively young field, having beendeveloped mostly during the 20th century.
Its mathematical frontiers continue to expand with the
aid of computers.
Major recent developments include
- Exploratory data analysis (EDA)
- Computer-intensive statistics
- Design of experiments- Robust product design
- Advanced Bayesian methods
- and more
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Applied Statistics inBusiness and Economics
End of Chapter 1