Education Technology

Solution 30651: Calculating a Median-Median Regression Using the TI-83 Family, TI-84 Plus Family, or TI-Nspire™ Handheld in TI-84 Plus Mode.

How do I calculate a Median-Median Regression using the TI-83 family, TI-84 Plus family, or TI-Nspire Handheld in TI-84 Plus mode?

Med-Med (median-median) fits the model equation y=ax+b to the data using the median-median line (resistant line) technique, calculating the summary points x1,y1,x2,y2,x3 and y3. Med-Med displays values for a (Slope) and b (y-intercept).

The following example will demonstrate how to calculate a Med-Med regression on your TI-83 family, TI-84 plus Family, or TI-Nspire Handheld in TI-84 Plus mode:

X= {15; 25; 50; 50; 75; 80; 95}
Y= {4; 9; 20; 31; 55; 42; 73}

Key the data into the handheld:

1) Enter STAT edit mode by pressing [STAT], [1].
2) Enter the data in the L1 and L2 lists, pressing [ENTER] after each entry.
3) Press [2nd] [QUIT] to leave the editor.



To calculate the Med-Med line, please follow the steps below:

1) Enter the STAT mode again by pressing [STAT].
2) Select CALC.
3) Press 3 to select Med-Med.
4) Press [ENTER] to get the Xlist and Ylist on the TI-84 Plus family and the TI-Nspire handheld in TI-84 Plus mode and store the equation into Y1=

See the screen shot below for the TI-84 Plus family and the TI-Nspire handheld in TI-84 Plus mode.



5) Select Calculate and press [ENTER] to perform the regression calculation.



Please Note: On the TI-83 family you are not going see the STAT template. Press [ENTER] after you select Med-Med to get your regression calculation.

See the screen shot below for the TI-83 family.



To set up the Stat Plot, please follow the steps below:

1) Press [2nd] [STAT PLOT].
2) Choose [1:Plot1].
3) Select ON and press [ENTER].
4) Select Scatter Plots and press [ENTER].
5) Make Xlist = L1 and Ylist = L2.

Please Note: Mark may be set to the first setting.



To graph the linear regression, please follow the steps below:

1) Press [Y=] the cursor should be beside Y1=.
2) Press [VARS] down to [5:] Statistics [ENTER].
3) Scroll to EQ press [1: RegEQ].
4) Press [GRAPH].
5) Press [ZOOM] and select [ZOOMSTAT] and press [ENTER].



Please see the TI-83 family and TI-84 Plus family guidebooks for additional information.