Scatter Plots

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Scatter Plots
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Scatter plots

• A graph that relates data from two different
  sets.
• To make a scatter plot, the two sets of data are
  plotted as ordered pairs

3
Positive Correlation

• Tilts up to the right
• Both sets of data increase together
• Both sets of data decrease together

4
Negative Correlation

• Tilts up to the left
• One set of data goes up while the other set goes
  down

5
No Correlation

• Data sets that are not related
• Dots are scattered and do not appear to have a
  pattern or cluster

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Identify the correlation

• The number of empty seats in a classroom and the
  number of students seated in the class
• The number of pets a person owns and the number
  of books that person read last year
• The monthly rainfall and the depth of water in a
  reservoir

Negative
No correlation
Positive
7
Trend Line

• Shows a correlation more clearly
• Allows you to predict other related data
• Makes it easy to determine a positive or negative
  correlation
• Can be helpful when making predictions based on
  data.

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What kind of correlation?

• The number of umbrellas sold vs. the number of
  rainy days.
• The number of minutes spent brushing your teeth
  vs. the number of cavities.
• The number of people in this class vs. your bus
  number.

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What kind of correlation?answers

• The number of umbrellas sold vs. the number of
  rainy days. positive
• The number of minutes spent brushing your teeth
  vs. the number of cavities. negative
• The number of people in this class vs. your bus
  number. No correlation

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Scatter Plots

• Press STAT
• Go to EDIT
• Enter the data from the first list in L1
• Enter the data from the second list in L2
• Go to STAT PLOT (2nd Y)
• Go to 1(PLOT 1), enter
• Put the cursor on ON and press enter

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• Go to TYPE. Make sure the scatter plot is
  highlighted (the first one)
• Make sure the XLIST reads L1
• Make sure the YLIST reads L2
• Go to ZOOM
• Go down to number 9 ZoomStat and press enter.

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Creating a Trend Line

• Press STAT
• Cursor over to CALC
• Go to number 4LinReg (ax b)
• Press enter
• Type in 2nd L1(1) , 2nd L2(2) , VARS
• Cursor over to Y-VARS, press enter, enter, enter
• Press Graph

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Number 27

• Juan and his parents are visiting
• a university 205 miles from
• their home. As they travel,
• Juan uses the car odometer and
• his watch to keep track of the
• distance.
• Make a scatter plot
• Describe the correlation
• Draw a trend line and predict
• the distance Juan would have
• traveled going to a
• university 4 hours away.

Time (Min)
Distance (Mi)
0 0 30 28 60 58 90
87 120 117 150 148 180 178 210 205