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
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
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