dhis2-users team mailing list archive

[Bob Jolliffe <bobjolliffe@xxxxxxxxx>]

Hi Bram

Interesting point about the red-yellow-green combo.  These are the traffic
light colours which are apparently sufficiently ubiquitous that you can say
red=bad and green=good without even explaining further.  If snooker was as
well known as traffic lights we could do a whole range from red through to
pink :-)

But in general, using hues as per Knut's colour brewer link is going to be
the best bet for most cases of numeric data.  You can even print to black
and white printers and maintain the message.

Good point about "equal counts".  I actually did do that but somehow it
rendered different on the dashboard.

Bob

On 20 February 2014 15:54, Bram Piot <bram.piot@xxxxxxxxx> wrote:

> Hi Bob,
>
> I don't think there's one single rule that will fit all when it comes to
> choosing your symbols or colours for a thematic map depicting numeric
> values. There's nothing wrong with say a red/yellow/green colour scheme if
> you are showing for example reporting rates, where low (red) = bad and high
> (green) = good. If I were to map out HIV prevalence, then I may go from
> green (low values) to red (high prevalence). More "neutral" variables such
> as population density are usually better off with a graduated scheme from
> light to dark, e.g. pale to dark brown.
>
> Maybe the only basic rules are that there should be some logic in the
> choice of colour ramps, and to keep it simple (don't overload your map,
> don't use 15 different classes each with a different colour when you only
> have 20 districts!). I must agree that the current colour scheme for ANC1
> and ANC2 coverage by chiefdom in the demo site can definitely be improved:
> too many colours that are not in a logical order. Your diarrhea map looks
> better, though it would be even better if you changed the classification
> type to "equal counts" rather than "equal intervals".
>
> Agree with what has been requested recently by Knut: option to display
> polygon data (e.g district) by symbol, not just colour, and include more
> symbols because currently it's rather limited. Especially for categorical
> values the legend behaviour could be greatly improved. Bar/Pie charts as
> symbols on the map would be cool but not a priority as there are more
> suitable tools for that.
>
> bram
>
>
> On 20 February 2014 17:27, Bob Jolliffe <bobjolliffe@xxxxxxxxx> wrote:
>
>> Hi
>>
>> I am no expert here, but I was talking last week with someone who had
>> just been on a GIS course.  She made the interesting observation that when
>> you are displaying numerical data as shaded regions on a map, you should
>> not mix primary colours in the same gradated scale because what you end up
>> with is sort of rubic cube kaleidoscope of colour rather than a clear
>> gradation of values.
>>
>> If that is good advice then I think our demo site could be improved as
>> presently it seems like a good example of bad practice, where we have mixed
>> red, green and blue with joyful and cheerful abandon :-)
>>
>> I had a go to change the Diarrhoea map on the dashboard at
>> http://apps.dhis2.org/dev/dhis-web-dashboard-integration/index.action and
>> I think it is true that it conveys the data better than the extreme
>> multi-coloured ones around it.  Even if the distribution of data between
>> bands is not so interesting.  Anyone agree or disagree? (the data will only
>> be there for a short while longer)
>>
>> If there is a best practice to be had here regarding colour selection I
>> guess we should promote it, particularly with default offerings so that
>> people have to be quite deliberate in order to go astray.
>>
>> Bob
>>
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>