<>
Probably a precision issue as in
***
clear*
inp double firstweight
13949.1460454864
13949.146248765
13949.146324324
end
gen byte dummy=1
su firstweight
tab dummy, /*
*/ sum(firstweight)
***
HTH
Martin
-----Ursprüngliche Nachricht-----
Von: [email protected]
[mailto:[email protected]] Im Auftrag von Ulrich Kohler
Gesendet: Dienstag, 15. September 2009 12:14
An: statalist
Betreff: st: Diffrence between sum and tabsum
<>
Does anybody know why -tabulate, summarize- displays a nonzero
standard-deviation for a variable that is a constant?
. tab seopsu if seopsu==948, sum(firstweight)
Cps Pr |
Sampl Un | Summary of firstweight
5:71-73 | Mean Std. Dev. Freq.
------------+------------------------------------
948 | 13949.146 .00024815 3
------------+------------------------------------
Total | 13949.146 .00024815 3
. sum firstweight if seopsu==948
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
firstweight | 3 13949.15 0 13949.15 13949.15
. return list
scalars:
r(N) = 3
r(sum_w) = 3
r(mean) = 13949.14646024504
r(Var) = 0
r(sd) = 0
r(min) = 13949.14646024504
r(max) = 13949.14646024504
r(sum) = 41847.43938073512
. d firstweight
storage display value
variable name type format label variable label
----------------------------------------------------------------------------
------
firstweight double %10.0g
. l firstweight if seopsu==948
+-----------+
| firstwe~t |
|-----------|
4256. | 13949.146 |
4365. | 13949.146 |
4537. | 13949.146 |
+-----------+
. about
Stata/MP 11.0 for Unix (Linux 64-bit x86-64)
Born 26 Aug 2009
Copyright (C) 1985-2009
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