Exploring Relationships Between Numerical Variables Scatterplots
Mar 22, 2016
Exploring Relationships Between Numerical VariablesScatterplots
Seating Chart
Try this …
• The first step in analyzing data it to make a ______.
• What is the slope of the following line?
graph
-1
Vocabulary
• A __________ helps us decide if there is a relationship between two numerical variables.
• The __________ variable is plotted on the x-axis.
• The ________ variable (the one we are most interested in) is plotted on the y-axis.
scatterplot
explanatory
explanatory
resp
onse
response
Golf• The goal of golf is to putt at or under
___.
• Every round starts off at the_______.
• The golfer must decide:• Hit ____(use a driver & hit off a
tee)• Hit ______(fairway has short grass)
• Very difficult to be accurate when hitting __.
Does the average driving distance affect accuracy?
par
tee box
long straight
far
Making a Scatterplot (by hand)① Decide which variable is the explanatory variable and label
the x-axis. Label the y-axis with the response variable.② Scale each axis individually.③ Draw a dot to represent each athlete.
Average Driving Distance
Driv
ing
Accu
racy
245 250 255 260 265 270 275
0.64
0.68
0.72
0.76
0.80
0.84
0.88
Making a Scatterplot (TI-84)
① Enter L1 (explanatory variable / x-axis) Enter L2 (response variable / y-axis)
② Turn the Scatterplot on
Making a Scatterplot (TI-84)
③ Look at the scatterplot
④ Check out the scale
Association: direction
There exists a relationship between the two variables.
Negative Positive
Association: no direction
If there is no relationship between the two variables, we say there is __ association. no
Mean Driving Accuracy
Mean Putting Average
Good DriversBad Putters
Bad DriversBad Putters
Bad DriversGood Putters
Good DriversGood Putters
Association: form
• Linear
• Non-Linear
Association: strength
• Very Strong • Strong
• Moderate • Weak
Sum it Up
• The _________ is a graph that displays the relationship between two numerical variables.
• In a scatterplot, the __________ variable is plotted on the horizontal axis and the ________ variable is plotted on the vertical axis.
• We can describe the __________ of two variables:• direction (________ or _______ )• form ( _____ or_________ )• strength (_____ to ____ )
scatterplot
explanatoryresponse
association positive negative
linear non-linearstrong weak