Download Mean absolute deviation (MAD)

Warm Up: Pick up the worksheet
on the front table and complete
Jan. 20th, 2015
Measures of Spread give us an indication of how
____________our
spread out
data set is. Here are some common
measures of spread.
Range –
The distance between the minimum and
maximum values in a data set
Mean absolute deviation (MAD) –
The average distance a set of data is from the mean
Mean Absolute Deviation
MAD =
𝑥1 −𝑥 + 𝑥2 −𝑥 +⋯+ 𝑥𝑛 −𝑥
𝑛
or
𝑁
𝑖=1
𝑥𝑖 −𝑥
𝑁
What does this mean?
Subtract the mean from each data point, make it
positive, add them up and divide that number by
the total number of data points
Steps for finding the MAD:
Vertically
Arrange your data set ______________.
mean
Find the __________
of your data set.
Subtract the mean from each of your data
_________
positive
points, keeping each difference _________!
sum
4. Calculate the _______
of your differences.
Divide
5. ________
the sum by the total number of
data points you have.
1.
2.
3.
List the data Difference
points
xx
Positive Value
Total:
N = _______
Mean = ____
Sum _____________
Mean Absolute Deviation:
= _________
Ex 3). The high (⁰F) for the last 7 days in two cities are given:
City A: 55⁰, 45⁰, 48⁰, 41⁰, 30⁰, 54⁰, 55⁰
City B: 67⁰, 68⁰, 65⁰, 64⁰, 61⁰, 62⁰, 69⁰
a) Find the mean, median, mode of each data set. Round your
answers to the nearest tenth.
b) For each data set, determine which measure of central
tendency best represents the data. Explain.
c) Compare the two data sets using the mean.
Ex 3). The high (⁰F) for the last 7 days in two cities are given:
City A: 55⁰, 45⁰, 48⁰, 41⁰, 30⁰, 54⁰, 55⁰
City B: 67⁰, 68⁰, 65⁰, 64⁰, 61⁰, 62⁰, 69⁰
d) Compare the spreads of the data using the range.
e) Compare the spreads of the data using the mean absolute
deviation.
Assignment: SID.2 Measure of
Central Tendency/Spread
Jan. 20th, 2015