Mac 2233
Sections1.5 Linear Regressions/Review of Parabolas
A. STEPS FOR ENTERING DATA INTO A LIST:
STAT
1 ( for EDIT)
To clear existing data:
up arrow to highlight L1 or L2
CLEAR
ENTER
Type the data pressing ENTER after each number
When all data is entered, press
2nd MODE (for QUIT) to exit the data entry screen
B. STEPS FOR GRAPHING DATA IN A LIST
2nd Y= (to enter stat plot)
1 (to select PLOT 1)
Arrow keys to put the cursor on ON
ENTER
Arrow keys to put the cursor on the type of plot you want (scatter-plot or line graph)
ENTER
IF NECESSARY:
Change the Xlist to match the location of your x-values - typically L1.
Change the Ylist to match the location of your y-values - typically L2.
Use the Arrow keys to put the cursor on the type of mark you want the calculator to use in
making your plot - press ENTER
Note: Set the window. You can let the calculator set the window automatically by using ZOOM 9, but the min and max numbers will not be “ROUNDED”. To use this option, press ZOOM 9 in place of setting window manually and pressing “GRAPH”. You can see the xmin/xmax that the calculator selected by pressing WINDOW after graphing.
C. STEPS FOR DETERMINING A REGRESSION (LINEAR)
1. Enter the data points into L1 (x) and L2 (y) as indicated in A above.
2. Graph the data in the list as a scatter plot as indicated in B above.
3. Press MODE, FLOAT (floating decimals)
4. STAT, ® (CALC), 4 (Linreg), ENTER (Note you can choose quadratic, cubic, etc.., regressions,
also.)
5. Your calculator displays values for a and b
6. Record your equation as y = ax + b, rounding a and b to 4 decimal places unless otherwise indicated.
Note: Some calculators also display a value for r. This is known as the correlation
coefficient – the closer r is to a value of 1, the closer the line is to an EXACT fit.
7. To check the results, "paste" your equation into Y1 and graph using:
y=, VARS, 5 (statistics), ®® (eq), 1 (RegEQ), GRAPH
Your line should go APPROXIMATELY through your data points.
ANOTHER HELPFUL CALCULATOR FUNCTION AFTER YOU HAVE GRAPHED A CURVE WITH YOUR CALCULATOR:
D. GIVEN X, DETERMINE Y:
1. Graph the function on your calculator, after being certain that STAT PLOT is off. (Stat Plot is on if Plot1 is highlighted on the “Y=” screen. To cut it off, use arrow to put cursor on Plot1 and press ENTER. Plot1 should no longer be highlighted.)
2. 2nd TRACE (for CALC)
3. 1 (for VALUE), ENTER
4. Enter the x-value. ENTER The corresponding y-value will appear on screen. The x-value must be a coordinate of a graphed point in your window. Sometimes you have to change your window in order to include the x-value on your calculator screen.
Homework:
Page 71: odds 9 – 13, all 15 – 18, 19a-c, 21, 23