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cubic spline regression

marcokunzelmann

Community Trekker

Joined:

Jun 9, 2015

Hello everybody,

I'm looking for a solution to regress a bivariate data set with a cubic spline regression which has exactly 15 knots. It would be great if someone has a solution for me!

Greetings

1 ACCEPTED SOLUTION

Accepted Solutions
Solution

Hello and thanks for your answer! Exactly something like that, but the question is, does lambda represent the amount of knots for my cubic spline?

Edit// Ok I have read now, that your suggestion is a smoothing spline. Smoothing splines are not calculating with knots instead you have penalty function with the factor lambda. So the question is, is there another function in JMP that I can calculate the splines with knots?

By the way is there a nice feature how I can extract the formula of the spline regression and calculate "new" height values by just input the weight values?

Edit// I think I found a solution. The knotted spline effect should be fine for me, it is hidden under Analyze->FitModel->Attributes

To extract formulas and calculate new values, just click on the red red triangle->save columns->prediction formula

In the next step just write down the new x-values in the same column were the old x-values are already. The predicted values are displayed in the new column!

2 REPLIES
louv

Staff

Joined:

Jun 23, 2011

Something like this

Bivariate(

  Y( :height ),

  X( :weight ),

  Fit Spline( 15, {Line Color( {208, 64, 86} )} )

);


8930_Screen Shot 2015-06-15 at 9.04.25 PM.png

Solution

Hello and thanks for your answer! Exactly something like that, but the question is, does lambda represent the amount of knots for my cubic spline?

Edit// Ok I have read now, that your suggestion is a smoothing spline. Smoothing splines are not calculating with knots instead you have penalty function with the factor lambda. So the question is, is there another function in JMP that I can calculate the splines with knots?

By the way is there a nice feature how I can extract the formula of the spline regression and calculate "new" height values by just input the weight values?

Edit// I think I found a solution. The knotted spline effect should be fine for me, it is hidden under Analyze->FitModel->Attributes

To extract formulas and calculate new values, just click on the red red triangle->save columns->prediction formula

In the next step just write down the new x-values in the same column were the old x-values are already. The predicted values are displayed in the new column!