Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
From | "Nick Cox" <n.j.cox@durham.ac.uk> |
To | <statalist@hsphsun2.harvard.edu> |
Subject | st: RE: AW: Identifying unique values with codebook |
Date | Wed, 16 Jun 2010 15:13:08 +0100 |
As Martin says, at root this is a precision problem. Neither -codebook- nor anything else is to blame if it is presented with the same values. To hold very large integers you may need to consider -long- as another possibility, or even a string representation. Nick n.j.cox@durham.ac.uk Martin Weiss As -help data_types- says: "doubles have 16 digits of accuracy." So you can increase the digits of your "y" up to the point where even -double- can do nothing for you: ************* clear set obs 10 gen byte x=_n codebook x gen double y1 = 1000000000000000 + x gen double y2 = 10000000000000000 + x gen double y3 = 100000000000000000 + x gen double y4 = 1000000000000000000 + x codebook y? ins y? ************* Interestingly, -inspect- seems to differ from -codebook-`s opinion. Walter Garcia-Fontes I stumped into a problem when identifying unique values of a numeric variable using "codebook": if the values are large they will be identified as the same value. For instance I have a variable x with the following values: 0, 1, 2, ... 10 (that is 10 different values) codebook x reports "unique values: 10" Now do gen y = 100000000000000000 + x codebook y reports "unique values = 1" Is this a feature? * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/