Plot statement in Proc Power

Yasu — Fri, 16 Mar 2012 04:36:55 GMT

Hi,

Now I'm trying to draw a graph for the samplsize analysis with plot statement in power procedure,

and I find that the resut differss depending on the option of plot statement.

The SAS code is as follows:

/*PRG1*/
proc power;
pairedmeans test=equiv_ratio dist=lognormal
meanratio = 1.10
alpha     = 0.05
cv        = 0.15
corr      = 0
lower     = 0.8
upper     = 1.25
npairs    = 2 to 100 by 1
power     =. ;
plot min=2 max=100 yopts=(ref=0.9 crossref=yes);
run;

/*PRG2*/
proc power;
pairedmeans test=equiv_ratio dist=lognormal
meanratio = 1.10
alpha     = 0.05
cv        = 0.15
corr      = 0
lower     = 0.8
upper     = 1.25
npairs    = 2 to 100 by 1
power     =. ;
plot min=20 max=50 yopts=(ref=0.9 crossref=yes);
run;

/*PRG3*/
proc power;
pairedmeans test=equiv_ratio dist=lognormal
meanratio = 1.10
alpha     = 0.05
cv        = 0.15
corr      = 0
lower     = 0.8
upper     = 1.25
npairs    = 2 to 100 by 1
power     =. ;
plot min=2 max=100 yopts=(ref=0.9 crossref=yes) NPTS=1000;
run;

Where does the difference come from?

Does the precision of estimation differ depending on the option?

I'd appreciate it if someone would help me.

Yasu

Plot statement in Proc Power

SteveDenham — Fri, 16 Mar 2012 11:53:54 GMT

I think it all comes down to the granularity of the interpolation, so yes the precision differs depending on the option. Rather than NPTS=, you might specify STEP= in the plot statement, for spacing on the X-axis for the interpolation.

Steve Denham

topic Plot statement in Proc Power in Statistical Procedures

Plot statement in Proc Power

Plot statement in Proc Power