<s>
PS	O
is	O
an	O
interactive	O
computer	B-Application
program	I-Application
for	O
performing	O
statistical	B-General_Concept
power	I-General_Concept
and	O
sample	O
size	O
calculations	O
.	O
</s>
<s>
The	O
user	O
specifies	O
the	O
alternative	B-General_Concept
hypothesis	I-General_Concept
in	O
terms	O
of	O
differing	O
response	O
rates	O
,	O
means	O
,	O
survival	O
times	O
,	O
relative	O
risks	O
,	O
or	O
odds	O
ratios	O
.	O
</s>
<s>
Power	O
,	O
sample	O
size	O
,	O
and	O
the	O
detectable	O
alternative	B-General_Concept
hypothesis	I-General_Concept
are	O
interrelated	O
.	O
</s>
<s>
The	O
program	O
can	O
generate	O
graphs	O
of	O
the	O
relationships	O
between	O
power	O
,	O
sample	O
size	O
and	O
the	O
detectable	O
alternative	B-General_Concept
hypothesis	I-General_Concept
.	O
</s>
