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From |
Pham Ngoc Minh <minh.pn@tnu.edu.vn> |

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

Subject |
Re: st: data precision and problems therein |

Date |
Sat, 10 Nov 2012 10:20:30 +0900 |

Thank you Paul for elaborate explanations, and those commands work well. Minh On Fri, Nov 9, 2012 at 11:12 PM, Seed, Paul <paul.seed@kcl.ac.uk> wrote: > Ngoc Minh PHAM points to a problem with non-integer cut-points. > He can solve it with the -float()- function: > > Rather than > gen gly_haem_gt_6_1 = gly_haem > 6.1 > > He can use > gen gly_haem_gt_6_1 = gly_haem > float(6.1) > > Or (allowing for missing values ) > gen gly_haem_gt_6_1 = gly_haem > float(6.1) if gly_haem <. > > Or (perhaps easier to remember): > gen gly_haem_gt_6_1 = float(gly_haem) > float(6.1) if gly_haem <. > > This is because his variable is stored as a float (7 decimal places more-or-less), > but 6.1 is evaluated exactly (or at least to double accuracy). > Converting a float to exact is impossible (inventing extra decimal places); > but going the other way is easy (just rounding). And float(float(x)) is the same as > float(x), so extra float functions are not a problem. > > If Ngoc prefers to cut the other way... > gen gly_haem_ge_6_1 = float(gly_haem) >= float(6.1) if gly_haem <. > > > Paul T Seed, Senior Lecturer in Medical Statistics, > Division of Women's Health, King's College London > Women's Health Academic Centre, King's Health Partners > (+44) (0) 20 7188 3642. > >> Date: Fri, 9 Nov 2012 15:28:08 +0900 >> From: Pham Ngoc Minh <minh.pn@tnu.edu.vn> >> Subject: st: data precision and problems therein >> >> Dear statalist, >> >> I have a problem with data precision as follows: >> >> for example: glycated hemoglobin is 6.1 (%) visible in data editor, >> but it turns out 6.0999999 when clicked on, so are other numbers (5.6 >> becomes 5.5999999), etc. This affects results of creating dummy >> variables with pre-defined cut-points of values. How about the >> solution? >> >> Thank you for your advice >> >> Ngoc Minh PHAM >> National Center for Global Health and Medicine, Japan. >> * >> * For searches and help try: >> * http://www.stata.com/help.cgi?search >> * http://www.stata.com/support/faqs/resources/statalist-faq/ >> * http://www.ats.ucla.edu/stat/stata/ >> > > > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/faqs/resources/statalist-faq/ > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**References**:**RE: st: data precision and problems therein***From:*"Seed, Paul" <paul.seed@kcl.ac.uk>

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