# Linear regression - extracting info using matrix algebra

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Daniel Miller on 12 Oct 2019
Commented: Daniel Miller on 12 Oct 2019
Hello!
I have a preloaded data which contains four columns and each column contains the following data in the following order:
1. Income (dollars)
2. Education
3. A dummy variable, 1 for male and 0 for female
4. Another dummy variable, 1 for STEM and 0 for not STEM
I've been given the linear model:
INCOME = α + β1EDUCATION + β2MALE + β3STEM
I should answer the following questions:
a) How large is α in the above equation
b) How many dollars greater is the salary of a male than the salary of a female
From what I understand, I should start with storing each column in the data in separate variables. How would I do this?
Any hints to get me started with this task are appreciated!

Stephan on 12 Oct 2019
Edited: Stephan on 12 Oct 2019
add a column of ones to your matrix DATA in pos. 4. isolate income as a column vector and remove this column from DATA then use:
X = DATA\INCOME
you get the beta values (1-3) and the last one is alpha.
Also possible:
DATA = [DATA ones(size(DATA,1),1]
vals = DATA(:,2:end)\DATA(:,1)
The other stuff should be not a problem by using logical indexing.

Daniel Miller on 12 Oct 2019
Thank you so much! I'll try to solve as much as I can on my own from here on.
Stephan on 12 Oct 2019
Did you notice that you can accept and or vote for useful answers? If you have more problems come back with a new question.
Daniel Miller on 12 Oct 2019
Cheers, I forgot to do that!