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Analyzing Quantitative Research Data

VIEWS: 10 PAGES: 41

									Analyzing Quantitative
Research Data
The purpose of this session is to FAMILIARIZE
you with some base data analysis techniques,
NOT to make you an expert statistician.
Purpose of Data Analysis
   Describe or summarize data clearly

   Search for consistent patterns or themes
    among data

   Enable you to answer your research questions
Why Use Statistics?
   Statistics are powerful tools that help people
    understand interesting phenomena.

   “Whether you are a student, a researcher, or
    just a citizen interested in understanding the
    world around you, statistics can offer one
    method for helping you make sense of your
    environment” (Urdan, 2001).
Options for Calculating Statistical
Analysis
   Technological advances have made the
    process of statistically analyzing data easy
    enough for non-statisticians to do.

   While there are numerous statistical analysis
    programs available, most educators have easy
    access to Microsoft Excel which is capable of
    calculating even advanced statistical analysis.
Hands On-Activities
   In the slides that follow, you will have
    directions and see examples of how to
    actually analyze your data using Microsoft
    Excel.
   While reading these slides may be
    meaningful, I encourage you to work through
    the examples actually using Excel rather than
    just reading about how to do it.
Types of Statistical Analysis
   Descriptive
       Used to describe and summarize data


   Inferential
       Used to make inferences or predictions about the
        similarity of a sample to the population which
        from which the sample is drawn.
Common Types of Descriptive
Statistics
   Percentage (and usually the Frequency)
       The number per 100 individuals who achieved a
        certain score.
   Mean
       The arithmetic average of a distribution of scores
   Standard Deviation
       The average deviation between the individual
        scores in the distribution and the mean for the
        distribution
Descriptive Analysis
   Our Scenario:
   RQ: How do teachers feel about Supervisor support?

   Our Task:
   We will use this example to do a few things:
     Generate Frequency and Percentage data
     Calculate the Mean
     Calculate the Standard Deviation
   The Layout
       The Task
       Step-by-Step
       Movie demonstrating how to complete the steps.
Raw Data – Supervisor Questionnaire
Question 1 only
Frequency and Percentage
   From the raw data in the previous slide, we
    now need to summarize the frequency and
    percentage of responses for Item 1 on your
    questionnaire.
Calculating the Frequency in Excel
   Click in the cell where you want the percentage to be displayed.

   Click the fx to open up the Functions box.

   Select ALL from the SELECT a CATEGORY Dropdown Menu

   Select SUM from the SELECT a FUNCTION list (list is in alphabetical
    order)

   Select the cells you want to include in the sum calculation.

   Click OK.
How to Calculate the Frequency


            How to Calculate the Frequency

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Calculating the Percentage in Excel
   Click in the cell where you want the percentage to be displayed.

   Click the fx to open up the Functions box.

   Select STATISTICAL from the SELECT a CATEGORY Dropdown
    Menu

   Select AVERAGE from the SELECT a FUNCTION list (list is in
    alphabetical order)

   Select the cells you want to include in the average calculation.

   Click OK.
How to Calculate Percentages


              How to Calculate Percentages

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Frequency and Percentage
                              Frequency & Percentage Table for Item 1




             Strongly Agree                  Agree                      Disagree       Strongly Disagree




         #                %            #             %            #                %   #           %




Item 1   0                0            1             3%          24            75%     7          22%
Warning!!!!!
   Your book provides an example which calculates the
    mean and standard deviation for questionnaire items
    that use a likert scale.

   Given the attitudinal nature of the responses, it is
    really NOT appropriate to report such responses
    using a mean or standard deviation.

   Such responses are most appropriately reported as
    frequencies and percentages.
Scenario - Mean
   You are teaching 6th grade math and are
    interested in examining the effect of using the
    Wii Big Brain Academy to reinforce basic
    math and problem solving skills.

   H1: Use of the Wii Big Brain Academy will
    increase the basic math skills for 6th grade
    students at XYZ Middle School.
The Design
   A One-Group pre-test/post-test design will be used determine
    if the use of the Wii improves student performance.

   All 20 students in your 2nd period 6th grade math class will
    take a pre-test that measures their basic math and problem
    solving skills.

   You will then implement the use of the Wii for 10 minutes
    each day for 1 week to reinforce the math and problem
    solving skills.

   All 20 students will then take a post test that measures their
    math and problem solving skills.
When to Use Mean

   When you want to determine the “typical” or
    average level of performance for a group.

   As we prepare to ultimately analyze data to
    prove or disprove our hypothesis, we must
    first find the average scores on the pre-test
    and post-test for both 6th grade classes.
Calculating the Mean in Excel
   Click in the cell where you want the mean to be
    displayed.

   Click the fx to open up the Functions box.

   Select the AVERAGE Function from the SELECT a
    FUNCTION List.

   Select the cells you want to average.

   Click OK.
Movie of How to Calculate the Mean


                How to Calculate the Mean

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       Windows Media Player OR Real Player so you can view the movie.
When to Use Standard Deviation
   When you need to determine how much a set
    of scores vary from each other.

   For the purpose of this scenario, Let’s
    determine the standard deviation among the
    student’s scores on the pre-test and then on
    the post-test.
Calculating Standard Deviation in
Excel
   Click in the cell where you want the standard deviation to be displayed.

   Click the fx to open up the Functions box.

   Select STATISTICAL from the SELECT a CATEGORY Dropdown
    Menu

   Select STDEV from the SELECT a FUNCTION list (list is in alphabetical
    order)

   Select the cells you want to include in the standard deviation calculation.


   Click OK.
How to Calculate Standard Deviation


        How to Calculate Standard Deviation

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Inferential Statistics
Cheat Sheet
   Descriptive Research        Descriptive Statistics
    Design                       (mean, standard
                                 deviation, percentages)
   Correlational Research      Correlation Coefficient
    Design

   Experimental & Quasi-       t-test, sign-test, Mann-
    Experimental                 Whitney U-test,
                                 ANOVA, ANCOVA
Correlation Coefficient
   Used to examine relations between two             or more
    variables.
   Strength of the Correlation
       -1.0 – 1.0 (closer the number is to -1 or +1 the stronger
        the relationship)
   Types of Correlation
       Positive Correlation
       Negative Correlation
       No Correlation
   Pearson Product Moment Correlation Coefficient = r
Scenario
   In this example, we are interested to know if
    there appears to be a relationship between the
    number of hours students study for a test and
    their test scores.
Example 1 Raw Data

Participants    Hours Studying       Exam Score




Participant 1                    2                80




Participant 2                    3                85




Participant 3                    1                70




Participant 4                    8                90




Participant 5                    9                95
Calculating the Correlation Coefficient
   Click in the cell where you want the standard deviation to be displayed.

   Click the fx to open up the Functions box.

   Select ALL from the SELECT a CATEGORY Dropdown Menu

   Select CORREL from the SELECT a FUNCTION list (list is in
    alphabetical order)

   Select the cells you want to include in the standard deviation calculation.
    (Array 1 = 1st group of numbers # of hours studying, Array 2 = 2nd group
    of numbers exam scores)

   Click OK.
How to Calculate the Correlation
Coefficient

  How to Calculate the Correlation Coefficient

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Negative Correlation


             Negative Correlation Example

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No Correlation


                  No Correlation Example

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Group Comparison Data Analysis
Strategies
   Sign Test

   t-Test

   Mann-Whitney U-Test
Sign Test
   Used to determine whether posttest scores are
    different from pretest scores for one group
    (single variable = test scores).

   Determines significance of difference
    between means of one group.

   Used with One-Group Pretest/Posttest design
Scenario
   Going back to our previous example of the 6th
    grade match class using a one-group pre/post
    test design…

   Our directional hypothesis was:
       Use of the Wii Big Brain Academy will increase
        the basic math skills for 6th grade students at
        XYZ Middle School.
Preparing for the Sign Test
   Note the pretest score for each participant

   Note the posttest score for each participant

   Indicate whether there is a POSITIVE
    difference (+), a NEGATIVE difference (-),
    or NO difference (0) in the pretest / posttest
    scores for each student.
Calculating the Sign Test
   Note the total number of participants (N=)
   Count the number of students whose scores were not
    the same (all students with a + or -)
   Change the N= to be the total number of students
    whose scores changed.
   Count the number of Pluses
   Count the number of Minuses
   Which number is smaller? Assign that number to X
    = _____
Calculating the Sign Test Cont.
   Using the N= and the X=, refer to a “Sign Table” to
    determine the probability
   Typical level of significance = .05 (means there is a
    5% chance error factor
   Sign Test uses .10 level of significance which is less
    stringent
   Determine if the number on your Sign Test Table is
    greater than or less than .10.
   If less than .10 the scores are significantly different,
    if greater than .10 the scores are NOT significantly
    different.
How to Calculate the Sign Test


             How to Calculate the Sign Test

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Next Steps
   In part 2 we will examine how to determine a
    t-test, the Mann-Whitney U-test, and how to
    analyze qualitative data.
   In Vista, click on the Analyzing Data Website
    and then click on Analyzing Data PPT (part
    2).

								
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