EG381 Statistics �Introduction to Statistics� by 2nHCYXa

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									     EG381 Statistics


“Introduction to Statistics”

        E381 – Statistics
        Mr. Thomas Rich
             Week 1
Objectives for this Lecture
1. Review class syllabus and class
   structure
2. Define the fundamental terms used in
   statistics
3. Classify qualitative and quantitative
   data with regard to four levels of
   measurement
4. Explain the different types of data
   collected
5. Identify sampling techniques for a
   given sample
                                           2
Let’s start by introducing ourselves

        CLASS INTRODUCTIONS




                                       3
Next let’s examine the Class Syllabus...

               Questions?

         Please complete the
       Acknowledgement Forms

  Reiterate Some Important Points




                                           4
We are truly in an “information age”....data is
abundant, and usually free and easily accessible...
                Examples:
Impact of violent TV program on Children

    Outsourcing and its effects on the
               economy

                Global Warming

 Today the issue is usually not “we need
more data”....but “how do we use our data
           to make decisions”
                                                 5
Data is Abundant in Today’s Organizations…

    Most companies have information
systems that yield tremendous amounts of
                   data:

       Systems usage and frequency
             Web Page “Hits”
            Revenue and Sales
              Quality Control
      Individual Performance Metrics

   What Data is Collected at Your Job?
                                             6
Class Discussion Question....


What are some of your goals or
hopes in taking this course, and
 what do you believe will be the
 benefits of taking a Statistics
             class?


                                7
         What is “Statistics”??

Let’s hear from several of you on what you
  think the study of “statistics” is defined as...


“Statistics is defined as the science of
  collecting, organizing, analyzing, and
  interpreting data in order to make decisions.
  It uses mathematical formulas for analysis,
  and it involves the understanding and
  interpretation of the results.”

Look at examples on page 2....
                                               8
  So to understand “Statistics” we have to
understand the meaning of the word “data”...
 When we use the word “data” we mean:

 RAW DATA

    We get data from
      observations
      counts
      measurements




                                           9
 Two different types of data sets...

“Population” – all the data that is of
  interest
“Sample” – a subset of the population
         GPA’s of All ITT Tech Jax Students


                      GPA of ITT Tech Jax Students
                               in EG381



   For what reasons do we collect “samples” from
    populations? Why don’t we gather the entire
                    population?                      10
    Determine if the data set is
     “population” or “sample”
- The age of each state governor
- A satisfaction survey taken of all
  ITT Tech students
- The salary of 5 randomly chosen
  baseball players
- The weights of every fifth baby born
  in March at St. Luke’s


                                    11
 Two Major Branches of Statistics

I. Descriptive Statistics

II. Inferential Statistics

Look in your text at these definitions – p. 5

Which is the branch that involves organization,
   summarization, and display of data?

Which is the branch that involves use of a sample
   to draw conclusions about a population?

                                                  12
 Decide which part of the study represents the
 descriptive branch. What inferences might be
 drawn?
- “A survey of home mortgages in Jacksonville
    shows that foreclosures are increased 23%
    over last year.”


-   “A large sample of college students was
    studied over 10 years after their graduation,
    and their salaries increased on average 22%
    more than a comparative sample who did not
    graduate”


                                                    13
 Two ways to classify data....

I. Qualitative – attributes, labels,
    non-numeric
II. Quantitative – measurements or
    counts

Examples – classify the following
  Street Addresses
  Hair Color
  Phone Numbers
  RAM size in a computer
  Brand Name
                                       14
We also classify data according to the
“level of measurement”
Nominal – qualitative only

    Ordinal – qualitative or quantitative

         Interval - quantitative

            Ratio – quantitative
       Look at Chart on Page 12
                                            15
Experimental Design....basic steps to
designing a statistical study
 1. Identify the variables of interest and the
    population
 2. Develop plan for data collection
 3. Collect the data
 4. Describe the data using descriptive
    statistics
 5. Interpret the data and make inferences and
    conclusions
 6. Identify sources of error
                                                 16
When we collect data, we can do a
“census” or we can “sample”
 Census: “whole enchilada”, all the
 data


 Sample: “carefully selected
 subset” of the data

                                    17
Different methods of collecting samples
      Simple Random Sample
 Random Samples: every member
 of the population has an equal
 chance of being selected.
 Examples?




                                          18
Different methods of collecting samples
      Stratified Sample
 Stratified: sampling a little from
 defined classifications (or “strata”)
 of data
 Examples?




                                          19
Different methods of collecting samples
      Cluster Sample
 Cluster Sampling: sometimes data
 is broken into subgroups, each
 having similar characteristics
 Examples?




                                          20
Different methods of collecting samples
      Systematic Sampling
 Systematic – sampling every nth
 event
 Examples?




                                          21
Different methods of collecting samples
      Convenience Sampling
 Convenience – selecting data,
 well, as you can…
 Examples?




                                          22
In Class Activities

In your groups you will work on
   the in-class activities. When
 your group is done, come to the
    instructor to review your
             answers.



                               23
Homework #1
          Due Next Week:
        Section 1.1: #24, #30
        Section 1.2: #12, #14
        Section 1.3: #8, #15
Must be typed, Arial Font, 12 point type,
 double spaced
Due: Beginning Class
Give complete sentence answers,
 explaining and interpreting answers.   24

								
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