topic Re: Space Time Analysis Algorithm Question in Spatial Statistics Questions

Space Time Analysis Algorithm Question

ChongyangZhu — Mon, 09 Jul 2018 19:10:46 GMT

Hi all,

I'm trying to understand how the space time analysis tool works. However I can't find description on what the tool uses to perform Mann-Kendall Trend test.

(1) As shown in the ArcGIS Pro ToolReference website, quote:"The trend analysis performed on the aggregated variables or summary field values is based on the Mann-Kendall statistic." This suggests that the tool uses the aggregated value for the variable we choose.

(2) However, in another website describing How Emerging Hot Spot Works, the trends are describing as "increase or decrease in the intensity of clustering over time". I think the intensity of clustering is decided by the z-score/p-value of the spatial hot spot analysis rather than the aggregated value itself.

Which one is used performing Mann-Kendall Trend test in the Space Time Analysis tool? The aggregated Value or the z-score of the of each location at each time step?

Thanks in advance for the help!

Chongyang

Re: Space Time Analysis Algorithm Question

DanPatterson_Retired — Mon, 09 Jul 2018 19:49:58 GMT

Chongyang… as a side thought... they have a great resource site at...

Welcome to the Spatial Statistics Resources Page

with links to.....

Presentations
Hands-on
Tool Overview
- Space Time Pattern Mining
- Spatial Statistics
Additional Resources
- Summarize
- Find clusters
- Model relationships
- Space Time Pattern Mining
- Tips and tricks
- Putting it all together
- Articles and blogs
- Integrating ArcGIS and R]
- Model and script tools
- Read more
R-ArcGIS Bridge
Add-in

Perhaps there are some resources there in case the people that run Spatial Statistics are busy at U.C

Re: Space Time Analysis Algorithm Question

JenoraD_Acosta — Mon, 09 Jul 2018 20:02:02 GMT

Both are correct! The Mann-Kendall statistic is calculated for different things depending on which tool you are using.

1- When you are initially creating your cube (using either the Create Space Time Cube by Aggregating Points or Create Space Time Cube from Defined Locations tools), the Mann-Kendall is calculated for the aggregated values you are bringing into the cube.

2- When you are using the Emerging Hot Spot Analysis tool, the Mann-Kendall is calculated for the z-scores at each location.

Hope this helps! Let me know if you have any other questions.

-Jenora

Re: Space Time Analysis Algorithm Question

ChongyangZhu — Wed, 11 Jul 2018 21:37:35 GMT

Thank you, Jenora! This is really helpful! I didn't realize there's two steps of MK test at first.

-Chongyang

Re: Space Time Analysis Algorithm Question

ChongyangZhu — Wed, 11 Jul 2018 21:38:18 GMT

Thank you, Dan! This is also very helpful for my future reference!

-Chongyang