[EpiData-list] Time and time differences - recording of time variables

epidata-list at lists.umanitoba.ca epidata-list at lists.umanitoba.ca
Fri Nov 27 03:30:46 CST 2009


Projects where I needed date and time were

- Study on surgeries with start time and end time of surgery (some of which started before midnight and went on to the next day)

- Study on patients in intensive care units in which date and time of arrival and discharge was available up to minutes

I think having two fields is fine . 

However, it would be handy to have functions to convert hours.minutes.seconds into a fraction of day which then can  be added to a date which finally allows to calculate differences and things like that.

with best wishes


Marcel Zwahlen
Institute of Social and Preventive Medicine
University Bern, Switzerland

phone     ++41-31-631.3554
facsimile ++41-31-631.3520



-----Ursprüngliche Nachricht-----

Von: epidata-list at lists.umanitoba.ca [mailto:epidata-list at lists.umanitoba.ca <mailto:epidata-list at lists.umanitoba.ca> ]

Gesendet: Mittwoch, 25. November 2009 13:12

An: epidata-list at lists.umanitoba.ca

Betreff: [EpiData-list] Time and time differences - recording of time variables

As part of current development there is an issue of how time is best represented in data.

Recent years have added a date-time field to some database systems. In most cases for entry these are rather cumbersome to work with in practice in my experience.

The suggestion is to add one time field:

hh.mm.ss that is a time field with 6 digits.


Entered recorded

1 01.00.00 (one o'clock at night)

122 12.20.00 (20 minutes past twelwe)

182045 18.20.45 (20 minutes,45 seconds after 18 hours)

Functions will be needed e.g. to calculate time in hours, minutes or seconds from day1 time1 to day2 time2. Or conversion of an imported date-time value to separate the date into one field and the time into another.

Users are encouraged to give examples and discuss here on the list regarding:

a. Needs for recording of time

b. Examples of practical situations where this was needed c. In what format would users prefer recording.

Also whether there seems to be a need for a combined date-time field.


Jens Lauritsen

EpiData Association






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