Dear all,

I am learning Synthetic Control method, Stata has command
Code:
synth
.
When I read the paper, "Synthetic Control Methods for Comparative Case Studies: Estimating the Effect of California’s Tobacco Control Program"
there is a very important formula
Array
We need to minimize the formula to find the weight W. But there is also a V matrix in this equation.
Would you please help me that how can I select this V matrix?

Best,
Jack