Graphing and Interpreting Scatter Plots

Objective - To graph and interpret scatter plots.

Scatter Plot

• A scatter plot is a graph of a collection of ordered pairs (x,y).

• X –independent/horizontal axis• Y- dependent/vertical axis

• The graph looks like a bunch of dots, but some of the graphs are a general shape or move in a general direction.

Positive CorrelationReview

• X-coordinates and the y-coordinates both increase, then it is POSITIVE CORRELATION.

Real Life 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.

Age 1 2 3 4 5 6 7 8Height 25 31 34 36 40 41 47 55

Justification1. Trend is increasing.2. Correlation: Positive3. When the age increase the height

Negative Correlation

• X-coordinates and the Y-coordinates have one increasing and one decreasing, then it is NEGATIVE CORRELATION.

Real Life 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.

Age of car

1 2 3 4 5

Value $30,000 $27,000 $23,500 $18,700 $15,350

Justification1. Trend is decreasing.2. Correlation: negative3. When the age of car increase the value decreases

No Correlation

• no pattern• scattered• This means the two

are not related.

No Correlation

• Size shoe a baseball player wears and their batting average

• Not related because the shoe size does not make the player better or worse, then are not related.

Interpreting Scatter PlotsWeight Loss Over Time

0

50

100

150

200

250

0 2 4 6 8 10 12

Days worked out per month

Weig

ht

Weight

How shirts affect salary

0

100000

200000

300000

400000

500000

1 3 5 7 9 11 13 15 17

Shirts Owned

Sal

ary

How Study Time Affects Grades

0

20

40

60

80

100

120

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Time in hours

Ove

rall

grad

e

Linear trend or not a trend

a) c) e)

b) d) f)

NegativeCorrelation

PositiveCorrelation

ConstantCorrelation

Year

Sport Utility Vehicles(SUVs) Sales in U.S.

Sales (in Millions)

19911992

199319941995

0.91.1

1.41.61.7

x

y

Year

Veh

icle

Sal

es (

Mil

lion

s)

5

4

3

2

1

Justification1. Trend is ____________2. Correlation: 3.

I DO: Model and Guided Practice

We Do: Guided Practice

1. Use the given information to make a scatter plot. Make sure to include Name for Graph, label each axes, and have appropriate intervals.

Insert Lesson Title Here

Grading Period 1 2 3 4

Number of A’s 5 6 8 10

0

1

2

3

4

5

6

7

8

9

10

11

0 2 4N

umbe

r of

A's

Grading Period

Justification1. Trend is _____________.2. Correlation:______________3.

Partner Activity:Plot the data on the graph such that homework timeis on the y-axis and TV time is on the x-axis.

StudentTime SpentWatching TV

Time Spenton Homework

Sam

Jon

Lara

Darren

Megan

Pia

Crystal

30 min.

45 min.

120 min.

240 min.

90 min.

150 min.

180 min.

180 min.

150 min.

90 min.

30 min.

90 min.

90 min.

90 min.

Plot the data on the graph such that homework timeis on the y-axis and TV time is on the x-axis.

TV Homework

30 min.

45 min.

120 min.

240 min.

90 min.

150 min.

180 min.

180 min.

150 min.

90 min.

30 min.

120 min.

120 min.

90 min.

Time Watching TV

Tim

e on

Hom

ewor

k

30 90 150 210 60 120 180 240

240

210

180

150

120

90

60

30

Describe the relationship between time spent onhomework and time spent watching TV.

Time Watching TV

Tim

e on

Hom

ewor

k

30 90 150 210 60 120 180 240

240

210

180

150

120

90

60

30

Trend is decreasing.

Trend appears linear.

Negative correlation.

Time on TV Time on HW

You Do

Independent Work

Closure

• Fist of 5• Wrap Up