[OSGeo Africa] Comparing census and elections datasets

[Simphiwe mdluli]

Can someone please tell me the advantaged and disadvantages of
NeoGeography...



On Mon, Apr 14, 2014 at 7:52 AM, Gavin Fleming <gavin at afrispatial.co.za>wrote:

> Hi Adi
>
> The CSIR produced (still  produces?) a product called GAP, which
> aggregates or disaggregates many datasets to a common 'mesozone' layer
> where each polygon is roughly 50 sq.km and has boundaries based on those
> of other administrative layers or natural features. A published methodology
> is used to perform the aggregation / disaggregation. There are all sorts of
> statistical pitfalls in aggregating and disaggregating data into different
> areas and this methodology tries to address them. It isn't a simple task to
> do accurately.
>
> http://www.gap.csir.co.za/
>
> I'd suggest you try and obtain the GAP material and in particular the
> methodology and mesozone dataset. Doing this would result in more
> 'interoperable' results since the mesozone units become the ideal unit of
> comparison.
>
> Gavin
>
>
> On 13/04/2014 22:44, Adi Eyal wrote:
>
>> Thanks Hanlie and Charles
>>
>> Sounds like that's the only way to go. I was hoping that secretly,
>> StatsSA was remapping census data to various shapefiles. Charles,
>> happy to take a crack at it with you to try to develop a script that
>> will allow this remapping across different boundaries.
>>
>> Adi
>>
>> On 9 April 2014 10:14, Charles Rethman <rethman at me.com> wrote:
>>
>>> Dear Adi and everybody,
>>>
>>> I've been thinking about this. I think whatever happens you'll need to do
>>> some cookie-cutting.
>>>
>>> The best solution I think would be to make your algorithm in PostGIS and
>>> map
>>> it on QGIS.
>>>
>>> If you like, we could meet up and discuss the details further--and post
>>> our
>>> trials or results back to this forum? Where--Codebridge? contact me on
>>> rethman at me.com.
>>>
>>> Charles Rethman
>>> Wahenga Ltd.
>>> Director, Cape Town Office
>>>
>>> Cell: +27 71 6735502
>>> Tel: +27 21 6861510
>>> Skype: cwrethman
>>> PO Box 23507, Claremont, 7735, South Africa
>>> 19 Sans Souci Road, Newlands, 7700, Cape Town
>>>
>>>
>>> On 8 Apr 2014, at 7:12 AM, Adi Eyal <adi at code4sa.org> wrote:
>>>
>>> Hi All
>>>
>>> I would like map demographic data from the 2011 census on top of
>>> elections results from 2009. There seem to be two problems with doing
>>> this.
>>>
>>> 1. Old wards have disappeared and new ones have been created by MDB.
>>> 2. In some cases the same ward id has been re-used for completely
>>> different polygons.
>>>
>>> In short, the obvious approach of joining two datasets won't work. It
>>> is possible (but difficult) to calculate approximations by overlapping
>>> shapes from the two maps and using some sort of algorithm (possibly
>>> assuming uniform distribution of data points) to slice up one shape
>>> and fit it into another.
>>>
>>> I don't want to go down that route.
>>>
>>> Is there another to go about this?
>>>
>>> Thanks
>>> Adi
>>>
>>> --
>>> Adi Eyal
>>> Director
>>> Code for South Africa
>>> Promoting informed decision-making
>>>
>>> phone: +27 78 014 2469
>>> skype: adieyalcas
>>> linkedin: http://za.linkedin.com/pub/dir/Adi/Eyal
>>> web: http://www.code4sa.org
>>> twitter: @soapsudtycoon
>>>
>>> For more information on how to participate in the open data community
>>> in South Africa, go to: http://www.code4sa.org/#community
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>>
>>
>>
>
> --
> regards
>
> Gavin
>
> Gavin Fleming
> http://afrispatial.co.za
> t: 0218630660
> c: 0845965680
> f: 0866164820
>
>
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