[Graham Wells]

Ok, let me just ask a very simple question then about panel data.
when using xt commands, if I use xtsum with the same dataex as above:

xtsum price

Variable         |      Mean   Std. Dev.       Min        Max |    Observations
-----------------+--------------------------------------------+----------------
price    overall |      5.88   5.946427          1         23 |     N =      25
         between |             .5247378        5.4   6.444444 |     n =       3
         within  |             5.928236   .4355556   22.43556 | T-bar = 8.33333

xtsum gives the mean over every line, not by actual patients...
how can I get summaries for the price by num_id (n=3), not by N?

[Nick Cox]

How do patients enter here?

xtsum is irrelevant for that purpose unless num_id is the panel identifier.

Perhaps use tabstat or summarize with by() or by: as the case may be. But there can't be a single precise answer without a precise definition of summaries.

[Graham Wells]

num_id is the panel identifier.

. sum price

    Variable |       Obs        Mean    Std. Dev.       Min        Max
-------------+--------------------------------------------------------
       price |        25        5.88    5.946427          1         23

* sum of price in total data set:

display r(sum)
147

* mean price per observation

display 147/25
5.88

* price per actual person

display 147/3
49

How can you code for the "price per actual person", n = 3?

*** EDIT... is it possible to do this without collapsing?

[Nick Cox]

Your direct response to my detailed reply in #15 is to say "Ok" and then in #18 (if I understand you correctly) just ask the same question all over again.

My analysis in #15 implies to me that you are utterly confused about what you're calculating.

If I'm wrong you'll have to show that before I am able and willing to take this further.

Sorry if that seems unfriendly or unhelpful, but I can't say more.