Dear all,

I am using Stata 15.0 to find a synthetic control group using synth command. No matter how short my expression is, I receive the message "Expression too long" r(130).

The dataset consists of 540 time periods and 83 units (44,820 observations overall).

My shortest try was:

. synth ln_births urbanization, trunit(36) trperiod(510) counit(1 7)

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Synthetic Control Method for Comparative Case Studies
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First Step: Data Setup
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expression too long
r(130);

What can be the problem?

Thank you!