How to calculate average based on to conditions?

[Phuc Nguyen]

I have a panel dataset as below and I want to calculate the average:

clear
input float year1 long TYPE2 float(treat1 FAT_w1 post33 post33treat1)
2016 2 0 . 0 0
2016 3 . . 0 .
2017 3 . 105.86112 0 .
2018 3 . 169.16325 0 .
2021 3 . . 1 .
2019 4 1 . 1 1
2020 4 1 6.876883 1 1
2017 6 1 . 0 0
2018 6 1 2.2230647 0 0
2019 6 1 2.0798314 1 1
2020 6 1 1.665593 1 1
2021 6 1 1.4405484 1 1
2016 7 1 . 0 0
2017 7 1 9.328573 0 0
2018 7 1 14.143867 0 0
2019 7 1 16.777643 1 1
2020 7 1 19.836254 1 1
2021 7 1 13.363945 1 1
2016 10 0 . 0 0
2019 10 0 . 1 0
2020 10 0 10.358336 1 0
2016 11 0 . 0 0
2017 11 0 .6820889 0 0
2018 11 0 .8348646 0 0
2019 11 0 1.1720647 1 0
2020 11 0 1.3943592 1 0
2021 11 0 1.464206 1 0
2017 13 0 . 0 0
2018 13 0 14.170573 0 0
2019 13 0 17.122456 1 0
2020 13 0 10.125214 1 0
end
label values TYPE2 TYPE2
label def TYPE2 2 "2557XG", modify
label def TYPE2 3 "2563UY", modify
label def TYPE2 4 "2563UZ", modify
label def TYPE2 6 "2580PG", modify
label def TYPE2 7 "25846A", modify
label def TYPE2 10 "2621N5", modify
label def TYPE2 11 "2622UU", modify
label def TYPE2 13 "2625KH", modify

I want to calculate the average of FAT_w1 for each year 2016,2017,2018,2019,2020,2021 for each of group treat1=1 and treat1=0.

For the dataset above, the results should be:
Average for treat1=1 and year1=2016 is .
Average for treat1=1 and year1=2017 is 9.328
Average for treat1=1 and year1=2018 is 8.183
...
...
Average for treat1=1 and year1=2021 is 7.4
Average for treat1=0 and year1=2016 is .
Average for treat1=0 and year1=2017 is 0.682
...
Average for treat1=0 and year1=2021 is 1.464


Many thanks and best regards.

[Carlo Lazzaro]

Phuc:
do you mean something along the following lines?

. tabstat FAT_w1 if treat==1, by(year)

Summary for variables: FAT_w1
Group variable: year1

   year1 |      Mean
---------+----------
    2016 |         .
    2017 |  9.328573
    2018 |  8.183466
    2019 |  9.428737
    2020 |  9.459577
    2021 |  7.402247
---------+----------
   Total |   8.77362
--------------------

. tabstat FAT_w1 if treat==0, by(year)

Summary for variables: FAT_w1
Group variable: year1

   year1 |      Mean
---------+----------
    2016 |         .
    2017 |  .6820889
    2018 |  7.502719
    2019 |   9.14726
    2020 |  7.292636
    2021 |  1.464206
---------+----------
   Total |  6.369351
--------------------

.

[Nick Cox]

Also (Stata 17)

. table year treat1, stat(mean FAT_w1)

-----------------------------------------
        |              treat1            
        |         0          1      Total
--------+--------------------------------
year1   |                                
  2016  |         .          .          .
  2017  |  .6820889   9.328573   5.005331
  2018  |  7.502719   8.183466   7.843092
  2019  |   9.14726   9.428737   9.287999
  2020  |  7.292636   9.459577   8.376107
  2021  |  1.464206   7.402247     5.4229
  Total |  6.369351    8.77362   7.634756
-----------------------------------------

In Stata 16 and earlier, the syntax is different, so see the help for your version

[Phuc Nguyen]

Dear Nick Cox and Carlo Lazzaro

The codes work perfectly now. Thanks so much.

Best regards.