Transcript File

Remember the 3 Ms?
Mean, Median, and Mode
~Central Tendency~
Objective
The student will be able to calculate
measures of central tendency
(mean, median, and mode)
Mean = Average


Mean: the (sum of the data items) divided by
the number of data items.
These are data items:
2, 3, 4, 5, 8, 8, and 12
2 + 3 + 4 + 5 + 8 + 8 + 12
7 (total data items)
42 / 7 = the mean, which is 6
Mean is the average of a
set of data. To calculate
the mean, find the sum
of the data and then
divide by the number of
data.
A way to remember…Mean – It is very
mean because it makes you do all that
work! grrrrrrrrr
You try the next one!
ABC Warehouse sells
flat screen TVs at the
following prices: $350,
$275, $500, $325,
$100, $375, and $300.
What is the mean
price?
Median
What does this word make you think of…


The middle number of a set of data, arranged in
numerical order
Median is the middle of the road
How Tall are You?

Need 5 volunteers:


Need 1 more volunteer


What is the median height?
What is the median height?
What was different about our middle number?

Odd Number of Data Items:


the middle number when the data items are put in numerical
order.
Even Number of Data Items:

the two middle numbers when data items are put in numerical
order.
Median


1.


Find the median of this data set
4, 3, 7, 9, 5, 3, 1
Put them in order!
There are 7 numbers in total…looking for the
“middle” number
Median =
Mode
What does this word make you think of?




Mode: the data item that occurs the MOST
What is the mode from our previous data set?
4, 3, 7, 9, 5, 3, 1
3 is a mode for these data items.
How old are you?

Raise your hand if you are:
13
14
15
16
17

What is the mode?





Mean
The average
Median
The number or
average of the
numbers in the
middle
Mode
The number that
occurs most
Find me the M, M & Ms






12, 14, 26, 37, 8, and 14
Re-order: 8, 12, 14, 14, 26, 37, 26.
Mean: 19.6
Median: 14
How many Modes: 2
Mode: 14, 26
Find me ONLY Mode:



Grape, grape, banana, nectarine, strawberry,
strawberry, strawberry, orange, watermelon.
How many modes?
Just one: strawberry.
Find me the M, M & Ms






2.3, 4.3, 3.2, 2.9, 2.7, and 2.3.
Re-order: 2.3, 2.3, 2.7, 2.9, 3.2, 4.3.
Mean: 2.95
Median: 2.8
How many Modes? 1
Mode: 2.3
Outlier




Outlier: is a data item (data value) that is
much higher or lower than the other data
values.
Outliers can affect the mean of a group of
data.
Example: 2, 3.5, 1, 2,
5,000,000.
Example: 35, 45, 40, 37, -6.
Describing Data with M, M, & M.


You can use what you know about Mean,
Median, and Mode to describe data.
But figuring out which M describes it best is
difficult.
Nah! Its got to
be mean!
I think mode
describes it best!
Which M, M, & M is best?


The favorite movie of students in this class?
Mode: good for non-numerical data items and
for frequent occurrences.
Which M, M, & M is best?


The distances students in your class travel to
school.
Median: one student may live much further
than everyone else. When an outlier may
significantly influence the mean, we use
median.
Which M, M, & M is best?


The daily high temperature during a week in
July.
Mean: since daily temp. are not likely to have
outlier, mean is best. When data have no
outlier, use mean.
Measures and Central Tendency


Your text book is going to ask you determine
which MEASURE of CENTRAL TENDENCY best
describe the data.
Its just asking you to figure out which M works
with the data best!