How to create a loop to run my training dataset 1000 times?

I have my training dataset randomly selected from 80% of my (x,y) time-series, and my goal is to do polynomial curve fitting from degree one to four and find the best fitting looking at each RMSE

So my "training" is different subset of my whole dataset each time I run the command.

and each of the RMSE is also different for the same reason.

My goal is to run the whole session 1000 times and then find the average of each RMSE. For example, to have mean_RMSE1=sum of all RMSE1/1000 and so on. I want to select the smallest mean_RMSE over the four alternatives.

So how could I write the syntax to achieve this purpose?

[KSSV]

for i = 1:1000
    % DEfine training here 
    % Do what you want 
end

[Robin Li]

Thank you.

Then how can I get the mean of all the 1000 events?

[KSSV]

Initiliaze the requied values before loop...save them in the loop and after use mean.