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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

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

Subject |
st: RE: format & reshape time-of-day measures |

Date |
Sun, 17 Aug 2003 16:59:29 +0100 |

Steven_A Harvey > I have a set of data from which I am interested in > analyzing the time > of day at which some key behaviors take place. The data was > collected > from weekly surveillance visits in two different waves over > a period of > 15 weeks each. The form is: > > household (1-15) > week (1-14) > wave (1, 2) > hour (13:00 23:30) > > I have two questions: > > 1. The data was originally entered in Access where the > hour variable > takes the form ##:##. When I imported the data into Stata > v. 8 using > StatTransfer, Stata read the hour variable as a float and > assigned it a > display format of %8.0g. The values are now decimals with a range > of .125 to .979. How can I get Stata to recognize these > values as a > time-of-day and display them as ##:##? I think you need to import time of day as a string variable. For calculations, you may also need a numeric equivalent. Frankly, time of day manipulations are not well supported in Stata. See the archives for 28 January 2003 for a survey of bits and pieces known to exist by one person. > 2. If I'm not mistaken, I then need to reshape the data > from long to > wide so that each household becomes a single case and each > time-of-day > measurement (wave 1, week 1-14 and wave 2, week 1-14) becomes a > variable. So I should end up with 24 measurements for each of 15 > cases, right? (I currently have 368 "cases"--15 x 14 x 2 > minus some > losses to follow-up and some censored households--each > consisting of > the 4 variables above.) How can I use the reshape commands > given that > I have two levels of time measurements (wave & week)? I doubt very much that you need to -reshape-. Such a wide data structure would make most things harder and some things well nigh impossible in Stata. The only thing that springs to mind that would be easier is use of -egen, r*()- functions like -rsum()-. Even there alternatives exist. Nick n.j.cox@durham.ac.uk * * 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/

**References**:**st: format & reshape time-of-day measures***From:*Steven_A Harvey <sharvey@jhsph.edu>

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