Hello statalists,

I'm trying to loop some basic descriptive stats of age according to sex. Right now the matrix looks like this:

age[1,5]
mu_men sd_men mu_women sd_women p
Age 48.584151 22.583488 51.528371 22.524248 .

with codes:
matrix age = J(1,5,.)
matrix rownames age = "age"
matrix colnames age = "mu_men" "sd_men" "mu_women" "sd_women" "p"

tab1 sex if index==1

local j=1
local s=1 // s is for values of sex (1 = Men, 0 = Women)

while (`s'>=0){

quietly sum age if sex==`s' & index==1, detail
local mu=r(mean)
local sd=r(sd)


matrix age[1,`j']=`mu'
matrix age[1,`j'+1]=`sd'

local s=`s'-1
local j=`j'+2
}
But I would like to have the matrix to look like this:
mu sd
men
women
So I wrote the following codes:

matrix age = J(2,3,.)
matrix rownames age= "men" "women"
matrix colnames age= "mu" "sd" "p"
local s=1

while (`s'>=0) {

sum age if sex==`s' & index==1, detail
local mu=r(mean)
local sd=r(sd)

matrix age[`s',1]=`mu'
matrix age[`s',2]=`sd'

local s=`s'-1
}

I end up getting this error message: conformability error
r(503);

When I list the matrix, this is what I get:
mu sd p
men 48.584151 22.583488 .
women . . .
Why am I getting this error? It seems to happen as soon as Stata is trying to run the second row. How do I fix it? I am using Stata 15.1 on a PC, thanks!