# OLS regression for bootstrapped data

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Alma Bezares on 21 Apr 2016
Commented: Alma Bezares on 22 Apr 2016
Hi, I bootstrapped some data 1000 times and now I want to regress each one of the columns of that bootstrapped data (A) on two vectors. This is: Y= each column in A; X=two vectors, but the "regress" command is not working. Any suggestion? All the data has the same number of rows. Thanks!

jgg on 21 Apr 2016
Shouldn't you be repeating the regression command 1000 times? Something like:
for i = 1:1000
Y = A(:,i);
b(i) = regress(Y,X);
end
then do analysis on the 1000 b values reported?
Alma Bezares on 22 Apr 2016
Yes, that's exactly what I want to do. Do the regression 1000 times. The problem is that if I use the code that you suggested, it only does the regression on column 1000 and not on the rest of them. If I set Y=(1:i), the command won't work as I'm dealing with a matrix again.

jgg on 22 Apr 2016
To answer your question based on my comment. The command Y = A(:,i) selects the i-th column from the A matrix, so this will give you your 1000 results. For instance,
X = randn(5000,2); %fake data; use real data
A = randn(5000,1000); %fake data;
betas = zeros(1000,2);
for i = 1:1000
Y = A(:,i);
betas(i,:) = regress(Y,X);
end
Your estimates are stored in the betas matrix so you can average or consider standard deviation etc.

#### 1 Comment

Alma Bezares on 22 Apr 2016
That seems to work. Thanks a lot!!