Lecture 4.pdf


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Mean:

What is typical?
Measures of center
!
! point on which a distribution would balance
value that minimizes the sum of the squared values
!

! Trimmed mean
! Median: the value that minimizes the sum of
absolute deviations
Mode: the most common value
!

Mode
The value that occurs most frequently

!

!

!
!
!

Mode: quantitative variables (1)

modes or modal heights are 63” and 68” (bimodal)

Quantitative variable (height)
!

Interpretation:
!

cf
3
4
5
8
10
11
12

%
c%
25.00% 25.00%
8.33%
33.33%
8.33%
41.67%
25.00% 66.67%
16.67% 83.33%
8.33%
91.67%
8.33% 100.00%

The most common heights for recent Miss Americas are
63” and 68”

Height (X) # winners (f)
63
3
64
1
66
1
68
3
69
2
70
1
71
1

Mode: quantitative variables (2)

22.5 25.0 27.5 30.0 32.5 35.0 37.5 40.0 42.5 45.0 47.5

N = 96.00

Mean = 28.7

Std. Dev = 4.31

Starting salaries for BAs in sociology, 2000-2001

The most common starting salaries are in the mid-to-high $20s

Not so easy if everyone has a slightly different value
Here mode is about $24-$29K
Interpretation:
!

30

20

10

0

National Association of Colleges and Employers

Starting salary in thousands

survey of college placement offices