Finding that all elusive "line of best fit" is the key to good linear regression. By changing the slope and yintercept, you can get close to the perfect line for your data. Today we will use a little
device we found called the Least
Squares Analyzer. It lets you set up a grid, plot 6 points, and then
play with the slope and So go ahead and read the intro
example and look at the pictures, then click on the link and try it out
for yourself. We supply you with two sets of data points and a few questions
to get you going. 

Step 1: When you go
to the least
squares analyzer, this is what you will see at first.


Step 2: The first thing you want to do is find your slope control dot and swing it around a bit. Put it near the bottom of the y axis and leave it there for now. NOTE:
it's real important that you always be able to see that slope red dot.
If it goes off the page you won't be able to alter the slope.


Step 3: Now play with the dot at the origin, (0,0). If you move that dot the entire grid goes with it. Be sure you don't lose your slope dot as you move the origin. For our two examples, you will
need to set it so that the first quadrant fills most of the page.


Step 4: Now let's make
a grid with enough points to fit our data. If you move the red dot to
the right of the origin, you can create more squares. We will need 11
squares on the positive y axis.


Step 5: Now drag each
of the six points P(1) to P(6) onto your grid so that they represent your
six data points.


Step 6: Now experiment
by dragging your slope and yintercept dots until you think you have found
the "least square" area possible. When you find it, you will
have a line of best fit.


Step 6: Now select any two points on this line, find the slope between them, then substitute that slope and one of the points to find the equation for the line. For a refresher on this process read the lesson, Linear Regression Day 1. 

If you want to know the exact equation, you can always use a graphing calculator to do a regression or use the EQUATION GRAPHER. 

EXAMPLE 1: go to the LEAST SQUARES ANALYZER The other day Mrs. Bird was doing a survey on illegal gum chewing for the school newspaper. She visited 6 classrooms unannounced and did a quiet count of all the gum chewers in each room. She recorded the following data.


Now do the following steps:


EXAMPLE 2: go to
the LEAST
SQUARES ANALYZER


Now do the following steps:
For more regressions check out these: day1 activity  day 3 activity  day 4 activity  Barbie Bungee Activity 

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