# needmathhelp.com

Home
| Grade 1
| Grade 2
| Grade 3
| Grade 4
| Grade 7
| Grade 9
| Grade 10
| Grade 11
| Grade 12
| Cr8ive Minds
| Contact Us

## How to determine the equation of the median-median LOBF:

Step1: Rearrange the table of values,

based on x-coordinates, from smallest to largest,

remember to move ordered pairs when ranking, not just the x-coordinates.

Step 2: Split the data into three groups.

Determine group size by using: n divided by 3,

which could have remainder zero (R0), remainder one (R1), or remainder two (R2).

Make groups symmetrical, balance the remainder.

If R0, then each group has the same number of data.

ex. n=12, group sizes: 4, 4, 4.

If R1, then place extra piece of data in middle group.

ex. n=16, R1, group sizes: 5, 6, 5.

If R2, then place 1 piece of extra data in the first and last group.

ex. n=23, R2, group sizes: 8, 7, 8.

Step 3: Determine the x and y median for each group.

Since the x's are already ranked, select the middle position from each group.

The y's need to be rank within each group, then select the middle position.

Write the three ordered pair medians.

Group 1: M1 (x-median, y-median)

Group 2: M2 (x-median, y-median)

Group 3: M3 (x-median, y-median)

Step 4: Determine the slope using the first and third median ordered pairs (M1 and M3).

Step 5: Determine the y-intercept using:

b = (sum of y-medians minus slope times sum of x-medians) all divided by 3.

Step 6: write the equation of the median-median LOBF using the slope and y-intercept calculated in step 5 and step 6.

© Copyright 1994 - 2013 needmathhelp.com. All rights reserved.

Email: helpdesk@needmathhelp.com