# Fitting Lines to Data

## Key Questions

I think what you are looking for is Linear Regression calculation, such as provided by the good old Commodore SR4190R. Does your calculator support it?

#### Explanation:

See for example,

for the TI-83 and TI-84 calculators.

• Preferably, all of them.

If you have fantastic data, you should be able to draw a straight line through all of the points.

However, this is not true in most cases.

When you have a scatterplot where not all of the points line up, you have to try your best to draw a line that goes through the middle of the group of points, like this:

You can find the exact line that "best fits" your points by using a graphing calculator (it should be called "linear fit").

See below.

#### Explanation:

A outlier in the data is when it is not near or close to a set of points.

As shown above, the dot that isn't near or close to the other data point is an outlier.

• A scatter plot is simply a graph which shows the locations of all the data points in a set.

So if I have the set

my scatter plot would be

• A rough guide is to have approx half the points above and half of them below the line. You can find the mean of the $x$ values and the mean of the $y$ values and ensure the line passes through this point but it does not have to for most questions.