492 Statistical DisplaysEffect of Extreme Values
MUSIC DOWNLOADS (^) Music Downloads
SMTWTHF S
52306436
The number of songs
downloaded during
one week are shown
in the table. Which measure is most affected by Saturday’s
downloads?
With Saturday’s Downloads
Mean ^5 +^2 +^3 +^0 7 +^6 + 4 +^36 = ^567 or 8
Median 0, 2, 3, 4, 5, 6, 36
Mode no mode
Without Saturday’s Downloads
Mean ^5 +^2 +^3 + 0 +^6 +^4
6
= ^20
6
or 3 ^1
3
Median 0, 2, 3, 4 , 5, 6
3.5
Mode no mode
So, Saturday’s downloads affect the mean and the median. The
mean is affected the most in this example.
b. LIBRARIES The number of library Library Books Returned
MTWTHF
35 23 18 5 29
books returned at Edison Middle
School is shown in the table.
Which measure is most affected by
Thursday’s returned books?
The table lists some guidelines for using each measure of central
tendency.
Mean, Median, and Mode
Measure Most Useful When...
Mean the data set has no extreme values
Median
the data set has extreme values
there are no big gaps in the middle of the data
Mode the data set has many identical numbers
Mode Mode If every value
occurs once, then there is
no mode, not a mode of 0.
490_497_C09_L1_895130.indd 492 1/11/10 9:31 AM