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May 26, 2010 8:24 AM
(2907 views)

1 ACCEPTED SOLUTION

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May 26, 2010 1:10 PM
(4732 views)

Solution

I raised this question with JMP support and received the following which I have slightly paraphrased:

The smoother utilized in the Graph Builder platform is a cubic spline with a lambda of 0.05 and standardized X values. The same spline can be obtained through the Bivariate platform by selecting Analyze > Fit Y by X, supplying the Y and X variables, and clicking OK. On the resulting Bivariate report window, select Fit Spline > Other from the popup menu. Then supply a smoothness parameter (lambda) of 0.05, and check the Standardize X box.

This information is from the JMP Statistics and Graphics Guide for version 8.0.2 and this info is found on pages 929-930 in Chapter 43. This is in the section on "Changing the Graph Element".

The "standardization of X" has the same effect as subtracting the mean and dividing by the standard deviation for the X variable and then fitting the spline. The only difference is that in Graph Builder and the Fit Y by X platform, the data is still plotted on the original scale rather than the standardized scale. Using standardized X values seems to smooth out the fit a little

The smoother utilized in the Graph Builder platform is a cubic spline with a lambda of 0.05 and standardized X values. The same spline can be obtained through the Bivariate platform by selecting Analyze > Fit Y by X, supplying the Y and X variables, and clicking OK. On the resulting Bivariate report window, select Fit Spline > Other from the popup menu. Then supply a smoothness parameter (lambda) of 0.05, and check the Standardize X box.

This information is from the JMP Statistics and Graphics Guide for version 8.0.2 and this info is found on pages 929-930 in Chapter 43. This is in the section on "Changing the Graph Element".

The "standardization of X" has the same effect as subtracting the mean and dividing by the standard deviation for the X variable and then fitting the spline. The only difference is that in Graph Builder and the Fit Y by X platform, the data is still plotted on the original scale rather than the standardized scale. Using standardized X values seems to smooth out the fit a little

8 REPLIES

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May 26, 2010 1:10 PM
(4733 views)

The smoother utilized in the Graph Builder platform is a cubic spline with a lambda of 0.05 and standardized X values. The same spline can be obtained through the Bivariate platform by selecting Analyze > Fit Y by X, supplying the Y and X variables, and clicking OK. On the resulting Bivariate report window, select Fit Spline > Other from the popup menu. Then supply a smoothness parameter (lambda) of 0.05, and check the Standardize X box.

This information is from the JMP Statistics and Graphics Guide for version 8.0.2 and this info is found on pages 929-930 in Chapter 43. This is in the section on "Changing the Graph Element".

The "standardization of X" has the same effect as subtracting the mean and dividing by the standard deviation for the X variable and then fitting the spline. The only difference is that in Graph Builder and the Fit Y by X platform, the data is still plotted on the original scale rather than the standardized scale. Using standardized X values seems to smooth out the fit a little

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May 26, 2010 1:17 PM
(2670 views)

thanks, thats exactly the information I was looking for :)

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Oct 30, 2017 2:36 AM
(1872 views)

Hi,

Is there a way to extract the equations of the smoothed curves ?

Thanks

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Oct 30, 2017 10:46 AM
(1852 views)

@samir here are two posts on cubic splines.

this one is probably what you want (thanks @Duane_Hayes):

this one shows another way to get the coefficients; I used the smoothed spline values to control the color.

Craige

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Oct 31, 2017 6:27 AM
(1823 views)

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Thursday
(66 views)

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Yesterday
(43 views)

I can make sense in cases like this where the response has two levels and the factor is ordinal. In that case, the Y reflects the proportion of the two values and you get of the trend for how that proportion changes with the GPA. Your "Missing" value on the X axis, however, is categorically different and should be plotted separately.

A more common view for categorical data would be a stacked bar of the counts or proportions for each outcome for each GPA value.

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Yesterday
(39 views)

Thank you very much for your prompt reply and heartening answer.