William E Hammond wrote:
>Time to weigh in on fuzzy dates. We have been using fuzzy dates at Duke >and in TMR since the early 70s for just the reason Sam states. Often >patients will know on;y the year, more frequently the month and year only >but no date. We discover that partial data is much more useful than no >data. > >So we used fuzzy dates. The fuzzy dates are displayed with ?? for the >unknown parts. Whenever we sort, a fuzzy day sorts to the 15th of the >month, and a fuzzy year sorts to July. > Ed, presumably you meant "a fuzzy month". This is the design we have used, so that's encouraging (when can we install it at Duke?-). > Statisticians are generally unhappy >with fuzzy dates and want to throw them out. > I am not convinced that the statistical arguments are so great - I can see that there would be a skew towards things that happen more often on the 15th of the month, due to the day-less dates in the system, but I can't think of any clinical research that would be looking at that. Are there any studies on the dangers of fuzzy dates in statistical analysis? >But every one seems happy >when someone records the date of onset for hypertension as July 4, 1976. >Where is the hour, minutes and seconds. I argue that fuzzy dates are >acceptable and valid data points and should be used in statistical >analysis. > >In a datetime stamp, unknowns are stored as 00. Thank goodness, we use >another saymbol for a totally unknown date. > >Ed Hammond > - thomas beale - If you have any questions about using this list, please send a message to d.lloyd at openehr.org
