Transcript AutoCAD Architecture 2008: Part I: Getting Started

Chapter 6
Analyzing and Interpreting
Quantitative Data
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Creswell, Educational Research: Planning, Conducting, and
Evaluating Quantitative and Qualitative Research, 4e
© 2012, 2008, 2005, 2002 Pearson Education, Inc.
All rights reserved.
By the end of this chapter,
you should be able to:
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Identify the steps in the process of analyzing and
interpreting quantitative data
Describe the process of preparing your data for analysis
Identify the procedures for analyzing your data
Learn how to report the results of analyzing your data
Describe how to interpret the results
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-2
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Steps in the Process of
Quantitative Data Analysis
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Preparing the data for analysis
Conducting the data analysis
Reporting the results
Interpreting the results
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-3
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Preparing the Data for
Analysis: Inputting Data
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Score data by assigning numeric codes
to responses
Create a codebook
Use information from instruments when
possible as a part of coding scheme
Create a data file in data grid
Create variable, value labels
Clean database, missing values
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-4
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Determine Types of Scores to
Analyze
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Single item
Summed scores
Difference scores
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-5
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Selecting a Statistical
Program
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Statistical Package for Social Sciences
(SPSS) most popular
Other programs
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Minitab
JMP
SYSTAT
SAS
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-6
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Conducting Descriptive
Analysis
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Measures of central tendency (value or score that
represents the entire distribution)
 Mean: Typically called the “average”
 Median: The value or score that divides the top half
of a distribution from the bottom half
 Mode: The value or score that occurs most often
Measures of variability (describes the “spread” of the
scores
 Range: The difference between the highest and
lowest scores
 Standard deviation: The standard distance the scores
are away from the mean
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-7
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Conducting Descriptive Analysis
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Measures of relative standing
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Percentile rank: The percentage of
participants in the distribution with scores
at or below a particular score
Calculated score: Enables a researcher to
compare scores from different scales
Z-Score: A popular form of the standard
score, has a mean of 0 and a standard
deviation of 1
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-8
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Descriptive Statistics
Descriptive Statistics
Central
Tendency
Variability
Relative
Standing
Mean
Median
Mode
Variance
Standard Deviation
Range
Z-Score
Percentile
Ranks
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-9
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Inferential Statistics
Inferential Statistics
T-test
Analysis of
Variance
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
ChiSquare
6-10
Pearson
Correlation
Multiple
Regression
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Conducting Inferential
Analysis
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Hypothesis testing: A procedure for making decisions
about results by comparing an observed value of a
sample with a population value to determine if no
difference or relationship exists between the values
Confidence interval: The range of upper and lower
statistical values that is consistent with observed data
and is likely to contain the actual population mean
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-11
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Conducting Inferential
Analysis (cont’d)
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Effect size: A means for identifying the
practical strength of the conclusions
about group differences or about the
relationship among variables
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-12
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Conducting Hypothesis Tests
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Identify a null and alternative hypothesis
Set the level of significance (alpha level)
for rejecting the null hypothesis
Collect the data
Compute the sample statistic
Make a decision about rejecting/failing
to reject
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-13
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Selecting an Appropriate
Statistic
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Determine the type of quantitative research question
or hypothesis you want to analyze
Identify the number of independent variables
Identify the number of dependent variables
Identify whether covariates and the number of
covariates are used in the research question or
hypothesis
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-14
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Selecting an Appropriate
Statistic
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Consider the scale of measurement for your
independent variable(s) in the research question or
hypothesis
Identify the scale of measurement for the dependent
variables (e.g., continuous or categorical)
Determine if the distribution of the scores is normal or
skewed
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-15
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Normal Curve
34%
34%
13.5%
13.5%
2.5%
-3
2.5%
-2
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
Mean
+1
-1
Standard Deviations
6-16
+2
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
+3
The Normal Curve of Mean Differences of All
Possible Outcomes If the Null Hypothesis Is
True
Reject the
Null
Hypothesis
High Probability
Values If the Null
Hypothesis Is True
Extremely Low
Alpha=.025 Alpha=.025
Probability Values
If Null Hypothesis
Two-Tailed Test
Is True (Critical
Region)
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-17
Reject the
Null
Hypothesis
Extremely Low
Probability Values
If Null Hypothesis
Is True (Critical
Region)
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Outcomes of Hypothesis Testing:
Type I and Type II Errors
Decision Made by
the Researcher
Based on the
Statistical Test
Value
Reject the
Null
Hypothesis
Fail to Reject the
Null Hypothesis
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
State of Affairs in the Population
No Effect: Effect Exists:
Null True
Null False
Type I Error
(false positive)
(probability =
Alpha)
Correctly not
rejected:
no error
6-18
Correctly
rejected:
no error
(probability =
power)
Type II Error
(false negative)
(probability =
Beta)
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Reporting the Results
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Tables summarize statistical information
 Title each table
 Present one table for each statistical test
 Organize data into rows and columns with simple
and clear headings
 Report notes that qualify, explain, or provide
additional information in the tables, which can be
helpful to readers. Notes include information about
the size of the sample reported in the study, the
probability values used in hypothesis testing, and
the actual significance levels of the statistical test
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-19
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Reporting the Results (cont’d)
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Figures (charts, pictures, drawings) portray variables and their
relationships
 Labeled with a clear title that includes the number of the figure
 Augment rather than duplicate the text
 Convey only essential facts
 Omit visually distracting detail
 Easy to read and understand
 Consistent with and are prepared in the same style as similar
figures in the same article
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Carefully planned and prepared
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-20
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Reporting the Results (cont’d)
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Detailed explanations about statistical
results
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Report whether the hypothesis test was
significant or not
Provide important information about the
statistical test, given the statistics
Include language typically used in reporting
statistical results
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-21
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.
Discussing the Results
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Summarize major results
Explain why they occurred
Explain the implications of the results for the
audiences
Advance limitations
Suggest future research
End on positive note
Educational Research: Planning, Conducting,
and Evaluating Quantitative and Qualitative
Research, 4e – Creswell
ISBN: 0132755912
6-22
© 2012, 2008, 2005, 2002 Pearson
Education, Inc.
All rights reserved.