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Linear Correlation and Regression. Using the TI-83 or TI-84. Finding “r” and the trend line equation by using the calculator……. Before we begin, make sure that your diagnostic is turned on: Press 2 nd 0 Scroll down to diagnostic on Press Enter twice. Calculator Steps:
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Linear Correlation and Regression Using the TI-83 or TI-84
Finding “r” and the trend line equation by using the calculator…… • 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
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 • 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)
The equation for the trend line is now in “y =“. Press zoom 9 to see the scatter plot and the trend line. You can also graph it……
You try…… • Find: a. Correlation coefficient b. Trend line equation • Graph on graphing calculator. • Explain the meaning of the y-int and the slope.
Correlation Coefficient: -.944 Equation: y = -3.62x + 102.5
Equation: y = -3.62x + 102.5 • 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.
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) Equation: y = 5x + 60
Assignment…… • Use ONLY the TI-83 or TI-84 to find the values on the HW assignment.