Statistics Dont Delete
Transcript of Statistics Dont Delete
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Chapter
One
What is Statistics??
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Chapter One
What is Statistics?
GOALS
When you have completed this chapter, you will be able to:
ONE
Understand why we study statistics.
TWO
Explain what is meant by descriptive statistics and inferential statistics.
THREE
Distinguish between a qualitative variable and a quantitative variable.
FOUR
Distinguish between a discrete variable and a continuous variable.FIVE
Distinguish among the nominal, ordinal, interval, and ratio levels
of measurement.
SIX
Define the terms mutually exclusive and exhaustive.Goals
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Types of Statistics
EXAMPLE 2: According
to Consumer Reports,
General Electric washing
machine owners reported9 problems per 100
machines during 2001.
The statistic 9 describes
the number of problemsout of every 100 machines.
Descriptive Statistics: Methods of organizing,summarizing, and presenting data in an informative way.
EXAMPLE 1: A
Gallup poll found that
49% of the people in a
survey knew the nameof the first book of the
Bible. The statistic 49
describes the number
out of every 100persons who knew the
answer.
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DESCRIPTIVE STATISTICS
Most of the Statistical Information in
newspapers, magazines, company reports,
and other publications consists of data that
are summarized and presented in a form thatis easy for the reader to understand. Such
summaries of data, which may be tabular,
graphical or numerical, are referred to asDescriptive Statistics
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Types of Statistics
APopulationis a
Collection
of all possibleindividuals,objects, ormeasurements of
interest.
ASampleis a
portion, or part,of the population
of interest
Inferential Statistics: themethods used todetermine something about a population on the basis
ofa sample.
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Population (N) Sample (n)
Samples and Populations
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Types of Statistics
(examples of inferential statistics)
Example 2: Wine
tasters sip a few drops
of wine to make adecision with respect
to all the wine waiting
to be released for sale.
Example 1: TV
networks constantly
monitor thepopularity of their
programs by hiring
Nielsen and other
organizations tosample the
preferences of TV
viewers.
Example 3: The accounting
department of a large firm will
select a sample of the invoices to
check for accuracy for all theinvoices of the company.
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Using Statistics (Two Categories)
Inferential Statistics Predict and forecast
values of population
parameters Test hypotheses about
values of population
parameters
Make decisions
Descriptive Statistics Collect
Organize
Summarize
Display
Analyze
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Types of Variables
Gender EyeColor
For a Qualitative or Attribute Variable thecharacteristic being studied is nonnumeric.
Type of carState of
Birth
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Types of Variables
Number of children in a family
In a Quantitative Variable information is
reported numerically.
Balance in your checking account
Minutes remaining in class
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Types of Variables
Discrete Variables:can only assumecertain values and there are usually gaps
between values.Example: the number of
bedrooms in a house, or
the number of hammers
sold at the local Home
Depot (1,2,3,,etc).
Quantitative variables can be classified as either
Discrete or Continuous.
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Types of Variables
The height of students in a class.
A Continuous Variable can assume anyvalue within a specified range.
The pressure in a tire
The weight of a pork chop
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Summary of Types of Variables
Qualitative or attribute
(type of car owned)
discrete
(number of children)
continuous
(time taken for an exam)
Quantitative or numerical
DATA
countable measurable
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Contd
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HOW DO YOU DISTINGUISH BETWEEN
CONTINUOUS AND DISCRETE
CONTINUOUS DISCRETE
They are real numbers
Normally, they aremeasured values
They can not take a
single value. There is an
area associated with itThey are continuous
Requires less sample
size
They are whole numbers
Normally, they are countedvalues
They can take only Zero or
non-fractional positive
valuesThey are in steps of 1
Requires more sample size to
have the more precision
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SOURCES OF DATA
PRIMARY SOURCE
SECONDARY SOURCE
INERNAL RECORDS
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DATA SOURCES
Data are also available from a variety of industry
associations and special interest organizations
E.g.: Internet used by Companies
Maintaining websites that provide information like:General Information about the company
Data on Sales
Number of Employees
Number of ProductsProduct Prices
Product Specifications
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More Benefits of Using Internet
Access to Stock Quotes
Meal Prices at Restaurants
Salary Data
And Other Infinite Variety of information
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Managers wanting to use data and Statistical
Analyses as an aid to decision making must be aware
of the time and cost required to obtain the data
Use of existing data sources is desirable when data
must be obtained in a relatively short period of time
If important data are not readily available from an
existing source, the additional time and cost involved
in obtaining the data must be taken into account.
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In all cases, the decision maker should consider the
contribution of the statistical analysis to the decision-
making process
The cost of data acquisition and subsequent
statistical analysis should not exceed the savings
generated by using the information to make a better
decision.
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Levels of Measurement
There are four levels ofdata
Nominal
OrdinalInterval
Ratio
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Qualitative -
Categorical or
Nominal:
Examples are-
Color
Gender
Nationality
Quantitative -
Measurable or
Countable:
Examples are-
Temperatures
Salaries
Number of pointsscored on a 100
point exam
Types of Data
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Nominal data
Nominal levelData that is
classified into
categories and
cannot be arranged
in any particularorder.
Gender
EyeColor
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Levels of Measurement
Mutually exclusiveAn individual, object, or
measurement is included in only
one category.
Nominal level variables must be:
Exhaustive
Each individual, object, ormeasurement must appear in one
of the categories.
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Levels of Measurement
During a taste test
of 4 soft drinks,
Coca Cola wasranked number 1,
Dr. Pepper number
2, Pepsi number 3,
and Root Beer
number 4.
Ordinal level: involves data arranged in someorder, but the differences between data values cannot
be determined or are meaningless.
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3
4
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Levels of Measurement
Temperature on theFahrenheit scale.
Interval levelSimilar to the ordinal level, with the additionalproperty that meaningful amounts of differencesbetween data values can be determined. There is nonatural zero point.
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Levels of Measurement
Monthly incomeof surgeons
Miles traveled by salesrepresentative in a month
Ratio level: the interval level with an inherentzero starting point. Differences and ratios are
meaningful for this level of measurement.
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Nominal Scale- groups or classes
Gender
Ordinal Scale- order matters
Ranks (top ten videos)
Interval Scale- difference or distance matters
has arbitrary zero value.
Temperatures (0F, 0C)
Ratio Scale- Ratio mattershas a natural zero
value.
Salaries
Scales of Measurement
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Answer these
What is the level of measurement for each of the
following variables?
Student IQ Ratings
Distance students travel to class
Student scores on the first statistics test
A Classification of the students by State of Birth
A ranking of students by freshman, sophomore, juniorand senior
Number of hours students study per week
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What is the level of measurement for these items
related to the newspaper business?
The number of papers sold each Sunday during the
year 2004
The departments, such as Editorial, Advertising,
Sports etc
A Summary of the number of papers sold by country
The number of years with the paper for each employee
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Cross-Sectional and Time Series Data
Cross-Sectional data are the data collected at
the same or approximately the same point in
time.
Time series data are data collected over
several time periods.
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QUESTION
ANDANSWERS
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TESTYOURSELF
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The science of statistics includes which of the
following:
A. Organizing data.
B. Presenting data.C. Interpreting data.
D. All of the above.Option
D
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In descriptive statistics our main objective is to
A. Describe the population.
B. Describe the data we collected.
C. Infer something about the population.
D. Compute an average.
Option B
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Which of the following statements is true regarding apopulation?
A. It must be a large number of values.
B. It must refer to people.
C. It is a collection individuals, objects, ormeasurements.
D. None of the above.
Option C
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Which of the following statements is true regarding a
sample?
A. It is a part of population.
B. It must contain at least five observations.
C. It refers to descriptive statistics.
D. All of the above are correct
Option A
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A discrete variable is
A. An example of a qualitative variable.
B. Can assume only whole number values.
C. Can assume only certain clearly separated values.D. Cannot be negative.
Option C
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A Nominal Scale Variable is
A. Usually the result of counting something.
B. Has a meaningful zero point.
C. May assume negative values.
D. Cannot have more than two categories.Option
D
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The ratio scale of measurement
A. Usually involves ranking.
B. Cannot assume negative values.
C. Has a meaningful zero point.D. Is usually based on counting.
Option C
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The ordinal scale of measurement
A. Has a meaningful zero point.
B. Is based on ranks
C. Cannot assume negative values.
D. All of the above
Option B
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Categories are exhaustive when
A. There is a meaningful zero point.
B. The objects can be ranked.
C. Each object must appear in at least one category.D. Each object can be included in only one category.
Option C