It is clear from -describe- that you have successfully transferred UPC as a double. However, you have generated the new variable UPC1 as a float - losing some of the precision of UPC. To create a variable UPC1 that is identical to UPC, you need:
gen double UPC1=UPC
See the manuals for [U] 16.10 Precision and problems therein.
David
[email protected]
-----Original Message-----
From: Maoyong Fan [mailto:[email protected]]
Sent: 16 January 2005 06:16
To: statalist
Subject: st: A strange data problem
Dear Stata User,
I met a strange problem in dealing with my scanner data. I use stata transfer to transger the original data to dta files. One of my variables is UPC whose storage type is double. I found that when I generate a new variable equal to UPC, the new variable is totally different from UPC.
Like this:
gen UPC1 = UPC
gen diff = UPC1 - UPC
sum
des
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
UPC | 1780770 3.76e+10 1.96e+11 1.00e+10 2.72e+12
UPC1 | 1780770 3.76e+10 1.96e+11 1.00e+10 2.72e+12
diff | 1780770 144.9445 4290.722 -105114 116086
. des
Contains data from D:\temp\dairyHH1.dta
obs: 1,780,770
vars: 3 18 Jun 2003 13:27
size: 35,615,400 (66.0% of memory free)
-------------------------------------------------------------------------------
storage display value
variable name type format label variable label
-------------------------------------------------------------------------------
UPC double %15.0g UPC -
system/generation/vendor/item
UPC1 float %9.0g
diff float %9.0g
-------------------------------------------------------------------------------
Sorted by:
Note: dataset has changed since last saved
Anyone know what's wrong with this?
Warm regards,
Maoyong Fan
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