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Creating SAS data set of parameter estimates from PROC NLIN

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New Contributor LMB
New Contributor
Posts: 4

Creating SAS data set of parameter estimates from PROC NLIN

I have a data set containing 980 paired observations of fish length and age.  I would like to use a bootstrapping approach to examine how sample size affects the precision of model parameter estimates.

I have used the following program to successfully create a dataset where 3 fish per cm length class are selected 1000 times from the original dataset:

PROC SURVEYSELECT DATA = AGE OUT = SAMPLE

     METHOD = URS

     N = 3

     SEED = 9876

     OUTHITS

     REP = 1000;

     STRATA TLINT;

RUN;

Next I fit model parameters to each replicate in this dataset:

PROC SORT DATA = SAMPLE;

BY REPLICATE;

RUN;

PROC NLIN DATA = SAMPLE;

PARMS LINF = 550 K = .25 t0 = 0.1;

MODEL TL = LINF*(1-EXP(-K*(AGE-t0)));

BY REPLICATE;

OUTPUT OUT = FITTED;

RUN;

I would like to create a dataset that contains parameter estimates for each replicate.  The dataset would contain the following variables:

REPLICATE LINF K t0

and would look like this, for example:

1 568 .25 .02

2 520 .27 .14

3 491 .32 .01

etc.

I have also attached the SAS file.

Any help would be appreciated.

Attachment
Respected Advisor
Posts: 4,919

Re: Creating SAS data set of parameter estimates from PROC NLIN

Try adding the statement:

ODS OUTPUT ParameterEstimates=samplePE;

to your NLIN procedure.

PG

PG
New Contributor LMB
New Contributor
Posts: 4

Re: Creating SAS data set of parameter estimates from PROC NLIN

PG,

That was helpful in summarizing the parameter estimates by replicate.  However, is there a way to get them into a format that is easier to work with?  Ideally this would be a SAS data set.

New Contributor LMB
New Contributor
Posts: 4

Re: Creating SAS data set of parameter estimates from PROC NLIN

Actually I may be ok working with it by exporting to Excel.

Respected Advisor
Posts: 4,919

Re: Creating SAS data set of parameter estimates from PROC NLIN

In the example I gave, samplePE would be a SAS dataset containing the parameter estimates. That seemed to be what you wanted.

PG
New Contributor LMB
New Contributor
Posts: 4

Re: Creating SAS data set of parameter estimates from PROC NLIN

Got it. Thanks!

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