I fully agree. I think there is a need of a date-time variable at least in Analysis. That can allow users to group cases in different periods of time (hours or days) with the complexity of reprograming as we have to do now. We also need the posibility of labelling the epicurve at two diferent levels in the time axis so that we can clearly see days an hours for example. This is more or less solved in EpiInfo for Windows (the grouping part).

Jens, maybe you can have a look at the specifications for the epicurve I sent you earlier this year.

Another question regarding some of the graphs is the need of doing the graph by a second variable for example bar agegroup by sex or line month by year.

Thanks a lot Jens for all this job and thanks every body for their comments Pedro Arias

I agree. However, the question of x-axis increment is not fully defined. There are two aspects to this. The usual option /xinc= will only affect the labelling on the chart, as with other graphs. However, the interval used to define boxes is something that should also be an option with histogram. This is particularly important for epicurves. This means that we can avoid awkward recoding of variables (especially tricky with dates) to have an epicurve that groups cases by 4-hour intervals, for example, and also labels the x-axis every 12 hours:

epicurve onsettime case /xinc=12 /interval=4

The same would be true of a histogram by age, where we wanted age grouped by 5 years. I would prefer

   his age /interval=5 /xinc=10

or

   define age5 ##
   age5 = age div 5
   his age5 /interval=5

Right now, his and epicurve are constrained to intervals of 1, which means that labelling is not always correct.

Jamie Hockin Public Health Agency of Canada

Jens wrote:

...

After constructive comments from Egil Arnesen in Tromsø, Norway and searching in various textbooks I have decided that for v2 the following two definitions will be implemented:

histogram: A graph, where there is one bar for each value present in the data. The height of the bar corresponds to the count of records in the data. (possibly later the percentage of data). Each bar starts at the x-value which was in the data (e.g. age 45 is shown from 45-46.) And the width of one bar is the same as the unit of the x variable. The X-axis is numerical and can be scaled with minimum, maximum and increase.E.g. from 25 to 100 with tickmarks by 5 (25 30 35 ......95 100)

Bar: A graph, where there is one bar for each value represented in the data. The X-axis is categorical and the bar is centered around the tick mark, which would show the value label (or the value) given by the x value.

If anyone has comments to this please send to this list.

The principle of the histogram will be implemented also for EpiCurve (but has not been done yet). The mentioned implementation of bar and histogram should work from build 112 uploaded shortly before this mail. (Minor problem with the build 112 uploaded yesterday).

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End of EpiData-list Digest, Vol 43, Issue 5

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