Transcript 5-7 Statistic: Scatter Plots & Lines of Fit

Warm Up
Find the equation of a line passing
through (3, 4) and perpendicular to
1
y  x2
4
October 11, 2009
6-6 Scatter Plots & Lines of Fit
Objective: Interpret points on a
scatter plot. Write equations for
lines of fit.
1
A scatter plot is a graph in which two sets
of data are plotted as ordered pairs in a
coordinate plane.
2
Scatter plots are used to investigate a
relationship between two quantities
3
A positive correlation means as x increases, y
increases.
A negative correlation means as x increases,
y decreases.
There is no correlation means that x and y are
not related.
Examples:
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
Height 25
“
2 3
31 34
4
36
5
40
6
41
7
47
8
55
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 1
of
car
Value $30,000
2
3
4
5
$27,00 $23,50 $18,70 $15,35
0
0
0
0
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.
Scatter Plots
Determine whether a scatter plot of the data for the following might
show a positive, a negative, or no relationship. Please explain.
Study time, higher grades
Scatter Plots
Determine whether a scatter plot of the data for the following might
show a positive, a negative, or no relationship. Please explain.
Age of car, value of car
Scatter Plots
Determine whether a scatter plot of the data for the following might
show a positive, a negative, or no relationship. Please explain.
Height, intelligence
Scatter Plots
Determine whether a scatter plot of the data for the following might
show a positive, a negative, or no relationship. Please explain.
Shoe size, salary
Scatter Plots
Determine whether a scatter plot of the data for the following might
show a positive, a negative, or no relationship. Please explain.
Miles per gallon, gas expense
Scatter Plots
Determine whether a scatter plot of the data for the following might
show a positive, a negative, or no relationship. Please explain.
Education, salary
Scatter Plots
Determine whether a scatter plot of the data for the following might
show a positive, a negative, or no relationship. Please explain.
Wrist circumference, appetite
Scatter Plots
Determine whether a scatter plot of the data for the following might
show a positive, a negative, or no relationship. Please explain.
Birthdate, ring size
Scatter Plots
Determine whether a scatter plot of the data for the following might
show a positive, a negative, or no relationship. Please explain.
Windchill, ice cream sales
Scatter Plots
Determine whether a scatter plot of the data for the following might
show a positive, a negative, or no relationship. Please explain.
Age of tree, number of rings
Scatter Plots
Determine whether a scatter plot of the data for the following might
show a positive, a negative, or no relationship. Please explain.
Amount of snowfall, shovel sales
Scatter Plots
Determine whether a scatter plot of the data for the following might
show a positive, a negative, or no relationship. Please explain.
Hair length, hat size
4
If the data points do not all lie on a line, but are
close to a line, you can draw a line of fit.
Example:
1.The table shows the world population growing
at a rapid rate. Find a line of fit.
year
Population
(millions)
1650
1850
1930
1975
1998
500
1000
2000
4000
5900
Rectangle Family
Investigation
5
The calculator uses a statistical method
to find the line that most closely
approximates the data. This is called
the line of best-fit.
The Wave
Worksheet
Secret Message Chain
Bungee Barbie
Homework – WB pg.