1. Lesson 11.4: Scatter Plots Standards: M7D1f & M7A3a & c
Objective: To construct a scatter plot and determine the relationship between two variables.

2. Scatter Plot
A scatter plot is a graph of plotted points that shows if there is a relationship between two sets of data or two variables.
The graph looks like a bunch of dots, but some of the graphs have a general shape or move in a general direction.

3. This vertical line is called the y-axis.
THE COORDINATE PLANE y
This vertical line is called the y-axis.

4. This horizontal line is called the x-axis.
THE COORDINATE PLANE y 5 4 3 2 1 -1 -2 -3 -4 -5
This horizontal line is called the x-axis. x -5 -4 -3 -2 -1 1 2 3 4 5

5. The x-axis and y-axis separate the coordinate plane into 4 parts.5 4 3 2 1 -1 -2 -3 -4 -5
The x-axis and y-axis separate the coordinate plane into 4 parts. x -5 -4 -3 -2 -1 1 2 3 4 5
This point in the middle of the x-axis and y-axis is called the origin.

6. These parts are called Quadrants.
THE COORDINATE PLANE y 5 4 3 2 1 -1 -2 -3 -4 -5
Quadrant II
Quadrant I
These parts are called Quadrants. x -5 -4 -3 -2 -1 1 2 3 4 5
Quadrant III
Quadrant IV

7. y x THE COORDINATE PLANE ( 1 , 3 )5 4 3 2 1 -1 -2 -3 -4 -5
To locate a point anywhere on the grid, you need an ordered pair.
An ordered pair is a pair of numbers used to locate points on a grid. x -5 -4 -3 -2 -1 1 2 3 4 5
The FIRST number is called the X- coordinate.
( 1 , 3 )
The SECOND number is called the Y- coordinate.

8. Ordered pair to graph (x, y)
Construct a scatter plot to show the relationship between the hours spent practicing shooting darts and the dart shooting score.
Practice Time (hours)
Dart Shooting Score
Ordered pair to graph (x, y) 1 6
(1, 6) 2 8
(2, 8) 3 13
(3, 13) 4 20
(4, 20) 5 18
(5, 18) 27
(6, 27)

9. Ordered pair to graph (x, y)
Construct a scatter plot to show the relationship between the hours spent practicing shooting darts and the dart shooting score.
Practice Time versus
Dart Shooting Time 30
Ordered pair to graph (x, y)
(1, 6)
(2, 8)
(3, 13)
(4, 20)
(5, 18)
(6, 27) 25 20
Dart Shooting Score 15 10 5 1 2 3 4 5 6
Practice Time (hrs)

10. Positive Correlation
If the x-coordinates and the y-coordinates both increase, then the two variables are said to have a POSITIVE CORRELATION.
This means that both are going up, and they are related.

11. Positive Correlation
If you look at the age of a child and the child’s height, you will find that as the child gets older, the child gets taller. Because both are going up, it is positive correlation.
Can you think of any other examples of
variables with a positive relationship?
Age 1 2 3 4 5 6 7 8
Height “ 25 31 34 36 40 41 47 55

12. Negative Correlation
If the x-coordinates and the y-coordinates have one increasing and one decreasing, then the two variables are said to have a NEGATIVE CORRELATION.
This means that 1 is going up and 1 is going down, making a downhill graph. This means the two are related as opposites.

13. Negative Correlation
If you look at the age of your family’s car and its value, you will find as the car gets older, the car is worth less. This is negative correlation.
Can you think of anything else with
a negative relationship?
Age of car 1 2 3 4 5
Value
$30,000
$27,000
$23,500
$18,700
$15,350

14. No Correlation
If there seems to be no pattern, and the points looked scattered, then it is no correlation.
This means the two are not related.

15. No Correlation
If you look at the size shoe a baseball player wears, and their batting average, you will find that the shoe size does not make the player better or worse, then are not related.

16. Which scatterplots below show a linear trend?
Negative
Correlation
Positive
Correlation b) d) f)
Constant
Correlation

17. Objective - To plot data points in the coordinate plane and interpret scatter plots.y
Sport Utility Vehicles
(SUVs) Sales in U.S. 5 4 3 2 1
Year
Sales (in Millions)
1991
0.9
1992
1.1
Vehicle Sales (Millions)
1993
1.4
1994
1.6
1995
1.7
1996
2.1
1997
2.4
1998
2.7 x
1999
3.2
Year

18. Scatterplot - a coordinate graph of data points.y
Trend appears linear. 5 4 3 2 1
Trend is increasing.
Vehicle Sales (Millions)
Positive correlation.
Predict the sales in 2001. x
Year

19. Plot the data on the graph such that homework time
is on the y-axis and TV time is on the x-axis..
Time Spent
Watching TV
Time Spent
on Homework
Student
Sam
30 min.
180 min.
Jon
45 min.
150 min.
Lara
120 min.
90 min.
Darren
240 min.
30 min.
Megan
90 min.
90 min.
Pia
150 min.
90 min.
Crystal
180 min.
90 min.

20. Plot the data on the graph such that homework time
is on the y-axis and TV time is on the x-axis. TV
Homework
240
210
180
150
120 90 60 30
30 min.
180 min.
45 min.
150 min.
120 min.
90 min.
Homework
Time on
240 min.
30 min.
90 min.
120 min.
150 min.
120 min.
180 min.
90 min.
Time Watching TV

21. Describe the relationship between time spent on
homework and time spent watching TV.
Trend appears linear.
240
210
180
150
120 90 60 30
Trend is decreasing.
Homework
Time on
Negative correlation.
Time Watching TV