Spatial Query Not Producing Population Coverage Results

[ComradeMisbourne]

Hello all in the London group!

I'm looking for some assistance please regarding a spatial workflow which is not producing the correct results.

I inherited a workflow which was calculating UK population coverage based upon drivetime catchments (polygons) from a set of geographical location points.

1) One part of the workflow was producing total coverage of UK population

2) A secondary part of the workflow was producing two other results: a) percentage of UK population that are within the same drivetime as just ONE of the location points and b) percentage of UK population that are within the same drivetime as TWO OR MORE of the location points.

The drivetime was using the Trade Area spatial function to create the drivetime catchments, then an Inverse Intersection Spatial Process function to obtain the total UK population coverage result in 1)

Another Trade Area spatial function, combined with the first set of Trade Area catchments above was linked through a Spatial Match function, followed by two more Spatial Process functions (an Intersection Object; then Inverse Intersection Object) to produce the results for 2).

The end results, however, were not producing matching percentages. For example, a 10-min drivetime population coverage of say 40% was produced from 1) however the result of the two stats in 2) were not adding up to 40%. (population within reach of just 1 location point within 10 minutes, plus the population within reach of two or location points was not adding up to 40% when logically it should).

I logged a call through the Alteryx help system and spoke yesterday via a Teams call with a spatial expert who I believe was based in the US. It sounded like he was mobile and I found it hard to understand most of what he was saying. I don't think he was really closely inspecting my screen and the workflow although he did recommend replacing the Trade Area function with a more specific Non Overlap Drivetime function instead. Unfortunately I'm not obtaining any results at all now.

Is there a spatial expert based in the UK whom I could contact via Teams and work through this call please? I'm stuck!

It would be greatly appreciated.

I hope the above info is easy enough to follow but of course will provide additional detail if necessary.

Thanks in advance, Ben

[w_chivers]

Hi Ben,

I'm not a spatial expert myself so wouldn't be able to jump on a call with you. Sorry to get your hopes up with my reply... I'm not sure of the proprietary nature of the workflow or it's component parts but I have found the Alteryx community to very helpful at times when I'm stuck on particular issues.  Perhaps you can post it there and many people are very helpful, replying back with comments or alterations to the workflow.  Usually people will want an example workflow to look at it as it is often hard to fully grasp what is happening based on words alone - perhaps you could post a section of the workflow that isn't working or create a little demo/dummy example workflow trying to solve the same problem?

Ask a question: https://community.alteryx.com/t5/forums/postpage/choose-node/true/interaction-style/forum/board-id/d...

[Sidique]

Hi,

This guy has a spatial background and helps on the community here, maybe contact him.

https://www.linkedin.com/in/joseph-serpis-5849a564/

Fyi - Our company paid for his service.

[ComradeMisbourne]

Thanks. I wasn't sure if this London group was an area for community problem solving or not. Thanks for the tip.