Correlation copy

							Scatter Plots and
Correlations
Is there a relationship
between the amount of
gas put in a car and the
number of miles that can
be driven?
     Positive Correlation
As one set of data values increases, so
does the other.
Positive Correlation
20

18

16

14

12

10

8

6

4

2

0
     0   2   4   6   8   10   12
Is there a relationship between
  the number of things you buy
  at the mall and the amount of
  money you have left?
     Negative Correlation
As one set of data values increases, the
other decreases.
     Negative Correlation
25


20


15


10


5


0
     0   2   4   6   8   10
Is there a relationship between a
  person’s age and the temperature
  outside?
         No Correlation
There is no relationship between the
two sets of data.
         No Correlation
25


20


15


10


 5


 0
     0      5     10      15
Would a scatter plot show a
 positive,negative, or no
       correlation?
Number of pages printed by a printer
and the amount of ink left in the
cartridge.
– Negative Correlation!
Would a scatter plot show a
 positive,negative, or no
       correlation?

Age of a child and the child’s shoe size
– Positive Correlation!
Would a scatter plot show a
 positive,negative, or no
       correlation?
Number of letters in a person’s first
name and the person’s height.
– No Correlation!
Would a scatter plot show a
 positive,negative, or no
       correlation?

Shots attempted and the number of
points made in a basketball game
– Positive Correlation!
Would a scatter plot show a
 positive,negative, or no
       correlation?
Length of a taxi ride and the amount of
the fare
– Positive Correlation!
Would a scatter plot show a
 positive,negative, or no
       correlation?
Outside temperature and the cost of air
conditioning.
– Positive Correlation!
Would a scatter plot show a
 positive,negative, or no
       correlation?
Miles ridden on a bicycle and the
thickness of the tire tread
– Negative Correlation!
Would a scatter plot show a
 positive,negative, or no
       correlation?
Temperature outside and the amount of
clothing a person wears
– Negative Correlation!
Think of some situations that
          show a….
Positive Correlation:

Negative Correlation:

No Correlation:
  Which graph to use…..?
Use bar graphs to make comparisons.
Use line graphs to show change over time.
Use circle graphs to show percentage of a
whole.
Use histograms when the data is arranged in
intervals.
Use scatter plots to show correlations
between two sets of numerical data.
Using the appropriate measure
of central tendency
 In a company there are 10 employees
   who each make $10,000 per year. The
   boss makes $80,000 per year. A job
   recruiter tells applicants that the
   average salary at the company is
   $16,364.

 Is this misleading?
Which measure of central tendency did
 the job recruiter use?

 Which measure of central tendency
 should he have used?
What measure of central tendency
to use?
Use the mean when the data values are
 close together.
 Use the median when there are large
 gaps in the data values.
 Use the mode when looking for the
 most common outcome.