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From |
"Frank de Libero" <frank@data2information.com> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: RE: data representation |

Date |
Thu, 26 Dec 2002 22:05:57 -0800 |

The -float()- function rounds its argument to floating place accuracy, but doesn't change how it's stored since that's integral to its binary representation. In short, what you want is assert z_coef>=float(3.05) & z_coef<=float(5.55) Not commands like replace z_coef = float(5.55) if year == 1991 because, as assert told you, -float()- didn't (and can't) change how the number is stored. ..Frank -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu]On Behalf Of Katsuhide Isa Sent: Thursday, December 26, 2002 5:22 PM To: statalist@hsphsun2.harvard.edu Subject: st: data representation Hello, I'm annoyed by the following problem. I issued the following commands. ---------- generate z_coef = . replace z_coef = 5.10 if year == 1989 replace z_coef = 5.40 if year == 1990 replace z_coef = 5.55 if year == 1991 /*max*/ replace z_coef = 5.15 if year == 1992 replace z_coef = 4.00 if year == 1993 replace z_coef = 3.05 if year == 1994 /*min*/ replace z_coef = 3.78 if year == 1995 replace z_coef = 4.00 if year == 1996 replace z_coef = 3.50 if year == 1997 replace z_coef = 4.10 if year == 1998 replace z_coef = 4.10 if year == 1999 replace z_coef = 4.10 if year == 2000 replace z_coef = 4.10 if year == 2001 assert z_coef>=3.05 & z_coef<=5.55 ---------- Then, Stata returned this error message: 7088 contradictions in 39384 observations assertion is false r(9); Given the above simple commands, this message is apparently hard to understand. So, I checked the 'z_coef' variable in Stata editor. Then, I found 5.55 actually stored as 5.5500002 and so on (Of the above figures, 3.05,3.78 and 4.00 are shown exactly as they are supposed to be) According to '[U] 16.10 Precision and problems therein.', this is because 'Stata stores numbers internally in binary'. I understand this logic, but this manner is sometimes inconvenient, especially when one wants to perform commands like -assertion-. Though the manual recommends the use of float( ), like, replace z_coef = float(5.55) if year == 1991 this mehod doesn't seem to deliver the goods; the results are the same. Though this phenomenon may not affect the data analysis, it makes me somehow embarrassed, given the above error message against -assertion-. Is there any other way to deal with this problem? Any suggestions welcome. Thanks in advance. K.I. * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**st: Re: RE: data representation***From:*"Katsuhide Isa" <CQB01114@nifty.ne.jp>

**References**:**st: data representation***From:*"Katsuhide Isa" <CQB01114@nifty.ne.jp>

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