how to know the number of treated onservations and number of controls for ssc command "kmatch"

[Fred Lee]

I tried to learn from its help file, however, I didn't get it claerly So how to know the number of treated onservations and number of controls after mach using "kmatch"

Thanks a ton!

ssc install kmatch,replace
webuse cattaneo2, clear
kmatch md mbsmoke mage prenatal1 mmarried fbaby (bweight), att wgenerate(_weight)

[George Ford]

The matching statistics are reported in the first table, no?

[Fred Lee]

However, I am wondering why the observation number is different from the number of observation in following regression?
The syntax of results in the below table is : reg bweight mbsmoke mage prenatal1 mmarried fbaby [pweight=_weight]
Sorry that my situations didn't occur in the example code I used. But I want to figure out what are the numbers of treatment group and control group for 2760, and why (919+1921) become 2760?
Thanks!

[Fred Lee]

It seems because some _weight calculated is 0. Why the weight calculated cab be 0?