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McGraw-Hill/Irwin © 2003 The McGraw-Hill Companies, Inc.,All Rights Reserved.
ANALYSIS AND
PRESENTATION OF DATA
Dr. Ratna Candra Sari
Email:
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Descriptive Statistics
•
Distribution Descriptors
–
Location
• Central Tendency
– Mean
– Median
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Descriptive Statistics
•
Distribution Descriptors
–
Spread
• Variance,
• Standard Deviation,
• Range,
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Descriptive Statistics
•
Distribution Descriptors
–
Shape
•
Skewness
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Techniques to Display
and Examine Distributions
•
Frequency Table
•
Visual Displays
– Histograms
–
Stem-and-leaf display
–
Box-plot
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•
Research Without Hypothesis
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Types of Hypotheses
•
Null
– that no statistically significant difference
exists between the parameter and the statistic being compared
•
Alternative
– logical opposite of the null hypothesis
– that a statistically significant difference
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Logic of Hypothesis Testing
•
Two tailed test
– nondirectional test
– considers two possibilities
•
One tailed test
– directional test
– places entire probability of an unlikely
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Decision Errors in Testing
•
Type I error
– a true null hypothesis is rejected
•
Type II error
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Testing for Statistical Significance
•
State the null hypothesis
•
Choose the statistical test
•
Select the desired
level of significance
•
Compute the calculated difference value
•
Obtain the
critical value
