I have two variables X and Y.
X and Y are both vectors of dimension 8561X1
I want to regress X on Y using a cubic spline specification and then take the ratio X/, where , is the fitted values obtained from the cubic spline regression
And I want to place the knots at specific positions, eg, 2nd and 5th position.
I found the rcspline package and I did something like
[bhat f sse knots]=rcspline(X,y,knots);
but I am not sure how to address the knots's position.
Any help is greatly appreciated.