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## How can I fit a second order exponential decay to my data?

How can I fit a second order exponential decay to my data?

2 REPLIES 2  David_Burnham
Super User

## Re: How can I fit a second order exponential decay to my data?

The short answer is you use the Nonlinear platform: Analyze>Modeling>Nonlinear

Nonlinear Regression with Custom Models

Nonlinear Regression with Built-In Models

-Dave

## Re: How can I fit a second order exponential decay to my data?

Here is what I use to fit a Stretched Exponential, make a plot to  look for anomolies and fit using the Non-Linear platform.

Fade << New Column( "Stretched Exponential",

Numeric,

Continuous,

Formula( Parameter( {a = 1, b = -0.01, c = 0.2}, a * Exp( b * :Hours ^ c ) ) )

);

Y( :Std Output1 ),

X( :Hours ),

SendToReport(

Dispatch(

{},

"2",

ScaleBox,

{Min( 0.65 ), Max( 1.05 ), Inc( 0.05 ), Minor Ticks( 1 ),

Label Row Nesting( 1 ), Label Row( Show Major Grid( 1 ) )}

),

Dispatch(

{},

"Bivar Plot",

FrameBox,

{Frame Size( 375, 279 ), Row Legend(

Exp No,

Color( 1 ),

Color Theme( "JMP Default" ),

Marker( 0 ),

Marker Theme( "" ),

Continuous Scale( 0 ),

Reverse Scale( 0 ),

Excluded Rows( 0 )

)}

)

)

);

biv<<Journal;

Y( :Name("Std Output1") ),

X( :Name( "Stretched Exponential" ) ),

Iteration Limit( 100000 ),

Newton,

Finish,

By( :Device ID ),

Custom Inverse Prediction( Response( 0.7 ),

Term Value( Hours( . ) ) )

);

f_rep = f <<report;

rep=Report( f )[Outline Box (6)][Table Box(1)] << Make Combined Data Table;

rep<<Current Data Table<<Set Name("Combined T70 Predictions");

rep=Current Data Table();

rep<<New Column("Exp No", character, formula(Substr(  :Device ID , 1, 10 )));

Hope this helps. Please let me know if you need anything further.

Dave