P value for parameter estimates for a exponential model

Lorezo — Sun, 13 Dec 2020 20:24:23 GMT

Hi,

I am currently trying to have SAS output a p value for the parameter estimates of my model. I am currently trying to use an exponential decay curve. I have used the following inputs to have everything I need except the p values for the parameter estimates. Any helpful advice in the right direction would be great!

Thank you!

data tmaga;

input time sa;

infile datalines dlm='09'x;

cards;

0 84.46011014

0 84.70962302

0 80.96692981

0 82.96303286

1 95.06440758

1 93.69208673

1 85.20864879

1 76.97472372

1.5 59.88309139

1.5 64.62383612

1.5 68.61604221

1.5 55.14234665

2 82.4640071

2 68.61604221

2 67.74274713

2 57.88698834

3 94.19111249

3 75.72715932

3 78.97082677

3 77.34899304

4 78.47180101

4 55.01759021

4 54.89283377

4 83.96108438

5 61.13065579

5 45.91037006

5 43.29048482

5 54.01953869

;

run;

PROC NLIN Data=tmaga;

PARMS a=89 b=1;

MODEL sa = a*exp(-time/10)*b;

output out=modeltmaga predicted=sapred r=saresid;

run;

proc sort data=modeltmaga; by time; run;

proc sgplot data=modeltmaga;

scatter x=time y=sa;

series x=time y=sapred;

run;

Proc corr data=modeltmaga;

var time sapred;

proc summary data=modeltmaga;

var saresid sa;

output out=stats css(sa)=Total_SS uss(saresid)=Residual_SS;

run;

data modeltmaga;

set stats;

Rsqaured=1-(Residual_SS/Total_SS);

run;

proc print data=modeltmaga;

run;

Re: P value for parameter estimates for a exponential model

PGStats — Sun, 13 Dec 2020 22:41:52 GMT

Your equation is not right for estimating the decay rate. You should use:

PROC NLIN Data=tmaga outest=tmagaEst plots=fitplot;
PARMS a=90 b=0.12;
MODEL sa = a*exp(-b*time);
estimate "Decay" b;
run;

....

Thus, a decay estimate of 0.07 per time unit and a p-value = 0.0022

Re: P value for parameter estimates for a exponential model

Lorezo — Mon, 14 Dec 2020 04:59:15 GMT

Thanks so much this works perfect!

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P value for parameter estimates for a exponential model

Re: P value for parameter estimates for a exponential model

Re: P value for parameter estimates for a exponential model