row means different?

[River Huang]

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[River Huang]

Dear All, I ran the following code.

webuse grunfeld, clear

gen m0 = (invest+mvalue+kstock)/3
egen m1 = mean(invest+mvalue+kstock)
egen m2 = rowmean(invest mvalue kstock)
egen m3 = rowmean(invest-kstock)

with results

 list m0-m3 in 1/10, sep(0)

     +-------------------------------------------+
     |       m0         m1         m2         m3 |
     |-------------------------------------------|
  1. | 1132.967   1503.656   1132.967   1132.967 |
  2. | 1702.033   1503.656   1702.033   1702.033 |
  3. | 1984.867   1503.656   1984.867   1984.867 |
  4. | 1086.367   1503.656   1086.367   1086.367 |
  5. |   1615.8   1503.656     1615.8     1615.8 |
  6. | 1770.767   1503.656   1770.767   1770.767 |
  7. |   1772.8   1503.656     1772.8     1772.8 |
  8. | 1331.933   1503.656   1331.933   1331.933 |
  9. |   1605.8   1503.656     1605.8     1605.8 |
 10. | 1709.467   1503.656   1709.467   1709.467 |
     +-------------------------------------------+

My question is that: what is `m1' different from `m0', `m2', and `m3'? Thanks.

[Attaullah Shah]

m0, m2, and m3 are all the same, that is an average for each row. m1 first adds the three variable by row and then finds mean of that summed column, hence it is constant.

gen m1a = invest+mvalue+kstock

sum m1a

    Variable |        Obs        Mean    Std. Dev.       Min        Max
-------------+---------------------------------------------------------
         m1a |        200    1503.656    1681.516      65.27     9323.4

.

[River Huang]

Dear Attaullah, Got it and thanks.