# Knowledge Base

## Solution 34855: Calculating a Median-Median Regression Using the TI-84 Plus C Silver Edition Graphing Calculator.

### How do I calculate a Median-Median Regression using the TI-84 Plus C Silver Edition graphing calculator?

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-84 Plus C Silver Edition.

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

Key the data into the handheld:

• Enter STAT edit mode by pressing [STAT], .
• Enter the data in the L1 and L2 lists, pressing [ENTER] after each entry.
• Press [2nd] [QUIT] to leave the editor. • Enter the STAT mode again by pressing [STAT].
• Select CALC.
• Press 3 to select Med-Med.
• Press [ENTER] to get the Xlist and Ylist. • Select Calculate and press [ENTER] to perform the regression calculation. • Press [2nd] [STAT PLOT].
• Choose [1:Plot1].
• Select ON and press [ENTER].
• Select Scatter Plots and press [ENTER].
• Make Xlist = L1 and Ylist = L2.

Note: Mark may be set to the first setting.  