Counting Cross sections within panel

[Kwame Ohene Djan]

I have a set of observations on Institutions and these institutions fall under 3 main organizational categories: 1= Investor owned companies. 2= NGOs and 3= Cooperative organizations. In total I have 630 individual institutions but I would like to know how many organizations represent each category

[Carlo Lazzaro]

Kwame:
you may want to try something along the following lines:

egen flag=tag(institutions)
tab categories if flag==1

[Marcos Almeida]

Carlo already provided the solution to the problem.

Just as an alternative, after the command - xtset id year - we can type:

xttab institutions

The results are the same. To check how the results are on the same verge, please see the example below:

.  webuse nlswork
(National Longitudinal Survey.  Young Women 14-26 years of age in 1968)

. egen flag = tag (idcode)

. tab race if flag ==1

       race |      Freq.     Percent        Cum.
------------+-----------------------------------
      white |      3,329       70.66       70.66
      black |      1,325       28.13       98.79
      other |         57        1.21      100.00
------------+-----------------------------------
      Total |      4,711      100.00

.   xtset id year
       panel variable:  idcode (unbalanced)
        time variable:  year, 68 to 88, but with gaps
                delta:  1 unit

. xttab race

                  Overall             Between            Within
     race |    Freq.  Percent      Freq.  Percent        Percent
----------+-----------------------------------------------------
    white |   20180     70.72      3329     70.66         100.00
    black |    8051     28.22      1325     28.13         100.00
    other |     303      1.06        57      1.21         100.00
----------+-----------------------------------------------------
    Total |   28534    100.00      4711    100.00         100.00
                              (n = 4711)