# Matlab statsitics

Two related questions.

First - I need a good way to display error bars on a

scatter plot. I have a set of x and y data, that I have attached as a text file along with y+err and y-err data (denoted +/-). The err values vary from point to point, and +err and -err are not necessarily the same.

Second - I am using the data to get a slope and an intercept. Once I

know. I need an easy way to calculate the errors in

slope and intercept? (This may be more of a math question than a MatLab

question, but I assume someone here knows the solution.)

Thanks!

Please do an example In full detail since I will be doing this for my physics lab reports for the next two months and I really need to know how to do proper linear regression using Matlab.

Also I need a Chi square test to verify that my fit is in fact good. Can you also please explain that to me thanks! As you can see, I am not so great in Statistics so I need help.

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#### Solution Preview

The attached Matlab script has examples of how to plot error bars and how to estimate errors in slope and intercept of a linear fit.

File Rb85_N_mod.txt contains your original data with the "+/-" column removed.

Note that I ADDED ERRORS to you original data to make the illustration more visible, as your original errors ...

#### Solution Summary

This provides methods of working with errors and Chi square in Matlab.