Transcript Document
Treat everyone with sincerity,
they will certainly appear loveable and friendly.
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Applied Statistics Using SAS
and SPSS
Topic: Descriptive Statistics
By Prof Kelly Fan, Cal State Univ, East Bay
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Two Basic Strategies to Explore Data
Begin by examining each variable by itself.
Then move on to study the relationship
among the variables.
Begin with a graph or graphs. Then add
numerical summaries of specific aspects
of the data.
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Descriptive Statistics
Displaying data/variables with graphs
for categorical (qualitative) variables: Bar plot and Pie chart
for quantitative variables: Stemplot and Histogram
Describing data/variables with numbers
for categorical (qualitative) variables:
Relative Frequency (Sample Proportion)
contingency table
for quantitative variables:
to measure center: Mean and Median
to measure spread: Interquartile Range (IQR) and Standard
Deviation
outliers
five-number summary and boxplot
scatterplot
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Observed Data: Example 1
Gender
M
F
F
M
M
F
M
M
Height
(inches)
68.5
61.2
63.0
70.0
68.6
65.1
72.4
--
Weight
(pounds)
155
99
115
205
170
125
220
188
College
Sci
Bsns
Bsns
Sci
Eng
Bsns
Eng
Sci
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Controlled Data: Example 2
The tension bond strength of cement mortar is
an important characteristic of the product. An
engineer is interested in comparing the strength
of a modified formulation in which polymer latex
emulsions have been added during mixing to the
strength of the unmodified mortar. The
experimenter has collected 10 observations on
strength for the modified formulation and
another 10 observations for the unmodified
formulation.
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Modified
16.85
16.40
17.21
16.35
16.52
17.04
16.96
17.15
16.59
16.57
Unmodified
17.50
17.63
18.25
18.00
17.86
17.75
18.22
17.90
17.96
18.15
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SAS/SPSS Data Input
SPSS: One variable one column in the
work sheet
SAS: One variable one name
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