topic minus sqrt calculation in SAS Programming

minus sqrt calculation

chinna0369 — Fri, 08 Oct 2021 17:09:28 GMT

Hi all,

I have below derivation, can anyone help how can I implement this in sas?

Thanks,

Adithya

Re: minus sqrt calculation

Reeza — Fri, 08 Oct 2021 17:20:27 GMT

Depends on your data set up to some degree.

Assuming you have a data set with SCR, AGE and SEX as variables.

if sex='Female' then eGFR = 194
                                                *(SCR**(1.094))
                                                 *(AGE**(-0.287))
                                                 *0.739;
else if sex = 'Male' then eGFR = 194
                                                *(SCR**(1.094))
                                                 *(AGE**(-0.287));

@chinna0369 wrote:

Hi all,

I have below derivation, can anyone help how can I implement this in sas?

Thanks,

Adithya

Re: minus sqrt calculation

ballardw — Fri, 08 Oct 2021 19:25:26 GMT

I don't see a square root anywhere much less a negative one.

In SAS you use the ** operator to exponentiate a value:

data example;
    x= 123;
   /* calculate x squared*/
    y= x**2;
    /* x to the minus 0.287 power*/
    z= x**(-0.287);
run;

Re: minus sqrt calculation

Sajid01 — Sat, 09 Oct 2021 01:13:10 GMT

Hello @chinna0369
I would like to point that negative numbers have no real square root.

Incidentally in solving your equation there is no need to calculate a square root.

There are many approaches to solve your equations, I would prefer the following.

I am first creating a user defined function. This function can be used like any other function.

Then I have shown an example usage.

/* Creating function*/
proc fcmp outlib=work.userfuncs.mymath;
function egfr(gender, scr,age);
term1=194*input(&scr.,best12.)**(-1.094) *input(&Age.,best12.)**(-0.287);
if(upcase("&gender") eq "MALE")then factor=1;
 else factor=0.739;;
return (factor*term1);
endsub;


/* Example usage*/
options cmplib=work.userfuncs;
data _null_;
Gender=female;
scr=100;
age=50;
egfr=egfr(gender,scr,age);
put egfr=;
run;