# Linear Correlation and Regression

## Presentation on theme: "Linear Correlation and Regression"— Presentation transcript:

Linear Correlation and Regression
Using the TI-83 or TI-84

Finding “r” and the trend line equation by using the calculator……
Temp. Emergency Calls 68 7 74 4 82 8 88 10 93 11 99 9 101 13 Before we begin, make sure that your diagnostic is turned on: Press 2nd 0 Scroll down to diagnostic on Press Enter twice

Calculator Steps: Put x’s in L1 and y’s in L2. Press Stat Calc 4:LinReg Vars Y-Vars 1:Function Enter Enter You should see all data.

Correlation Coefficient “r” is equal to .811.
The trend line equation is y = .19x – 7.54

a. Explain the meaning of the y-intercept .
Temp. Emergency Calls 68 7 74 4 82 8 88 10 93 11 99 9 101 13 In the equation y = .19x – 7.54 a. Explain the meaning of the y-intercept . b. Explain the meaning of the slope.

Equation: y = .19x – 7.54 Temp. Emergency Calls 68 7 74 4 82 8 88 10 93 11 99 9 101 13 A. The number of emergency phone calls when the temp is 0. B. The number of emergency phone calls increases .19 for every degree increase in temperature. (The # of calls/degree temp increase)

You can also graph it…… The equation for the trend line is now in
Press zoom 9 to see the scatter plot and the trend line.

You try…… Find: a. Correlation coefficient b. Trend line equation
Graph on graphing calculator. Explain the meaning of the y-int and the slope. Absences Final Grade 6 82 2 86 15 43 9 74 12 58 5 90 8 78

Absences Final Grade 6 82 2 86 15 43 9 74 12 58 5 90 8 78

Correlation Coefficient: -.944
Equation: y = -3.62x

Equation: y = -3.62x + 102.5 Meaning of Y-Intercept:
Absences Final Grade 6 82 2 86 15 43 9 74 12 58 5 90 8 78 Meaning of Y-Intercept: The final grade when a student has 0 absences. (102.5) Meaning of slope: Final grade/absence – the grade decreases (3.62) for every absence made

Example…… Max used linear regression to help him understand the relationship between the temp and the number of ice cream cones sold. The line of best fit was y = 5x + 60, where x is the # of ice cream cones sold and y is the temp in degrees F. In terms of ice cream cones sold and temp answer the following.

Equation: y = 5x + 60 Explain the meaning of the y-intercept:
The temperature (60 degree F) when no ice cream cones are sold. Explain the meaning of the slope: The temperature increases 5 degrees F for every ice cream cone sold. (Temp/# sold)

Assignment…… Use ONLY the TI-83 or TI-84 to find the values on the HW assignment.