Hello,
I have 2 questions about matrix manipulation on my unbalanced
panel data sets:
with my old Stata matrix language I can create a sequence of
matrix by typing for exemple
local wave=1
while `wave'<22 {
matrix accum A`wave' = x1 x2 ..xk if t==`wave', noconstant
local wave=`wave' +1
}
How can i performs a similar task with Mata?
I don't seek for a complex way to things but in fact i would
like to write a more complex expression wich looks like:
for each time period t the matrix
A_{t} = sum_{i=1 to n} (s1_it * s2_it x_it' * x_it)
where , s1_it is a scalar =norm(xb) and
s2_it= normden(xb)
scalars s1_it and s2_it comes froma previeous probit estimation
any help?
AbdelRahmen El Lahga
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