Transcript Lesson 2 in SPSS

Lesson 2 in SPSS
How to find measures of central
tendency using SPSS
The Dataset
• Here’s a nice
dataset.
• We have one
variable called
Age.
• There are 1,207
observations in the
dataset.
First Blush
Frequency
• To get a quick
picture of this
dataset, let’s see
a frequency
distribution
histogram
(Lesson 1).
• Looks fairly
symmetric,
doesn’t it?
Age (years)
200
100
Std. De
Mean =
N = 120
0
20.0
30.0
25.0
40.0
35.0
Age (years)
50.0
45.0
60.0
55.0
70.0
65.0
80.0
75.0
90.0
85.0
Selecting the Analysis
• From the
SPSS menu
bar, choose
• Analyze
• Descriptive
statistics
• Frequencies
Select the Variable(s)
• In the
Frequencies
box, highlight
the variable
age, then click
on the arrow
to pop it into
the Variables
window.
Descriptives Box
• Notice that
when you’ve
done this, the
OK box is
now active.
• But let’s
make sure
we get the
statistics we
want.
Selecting the Statistics
• I’ve selected the
mean, median and
mode as my
measures of central
tendency. Plus, I
asked for the sum.
• Now click on Continue.
Running the Analysis
• Now we can
click on OK.
The Output
• So what did we
learn?
• The mean and the
median are both
right around 56
years of age.
Although the mode
is a little lower at
49 years old, we
still have a fairly
symmetric
distribution.
Statistics
Age (years)
N
Mean
Median
Mode
Std. Deviation
Variance
Range
Minimum
Maximum
Sum
Valid
Missing
1207
0
56.39
56.00
49
13.328
177.626
66
22
88
68060
Visual Representation
• Let’s mark
these on
our graph.
Age (years)
200
Mean &
Median
Mode
Frequency
100
Std. Dev
Mean =
N = 120
0
20.0
30.0
25.0
40.0
35.0
Age (years)
50.0
45.0
60.0
55.0
70.0
65.0
80.0
75.0
90.0
85.0