Spatial weight matrix error

[GlynisHumphrey]

Hi there,

I'm using the hot spot analysis to assess clustering/dispersion of of hot and cold fire spots and have generated a spatial weights matrix (.swm), however my weight column indicates the distance between points as 1 for all the point features. Please note I am using a projected data.

Any comments as to why, and how to trouble shoot this issue would be most appreciated.

Thanks in advance.

[DanPatterson_Retired]

From here

Generate Spatial Weights Matrix—Help | ArcGIS for Desktop what options did you use.

How Generate Spatial Weights Matrix works—Help | ArcGIS for Desktop

or were you using something else?

Do you want this directed to the Spatial Statistics or Spatial Analysis place?

[GlynisHumphrey]

Yes, I'm using the links you provided.  Please could you direct this question to the spatial statistics/spatial analysis group.

Thanks.

[DanPatterson_Retired]

What were the parameters used?  This has a large impact on results.

And you are absolutely sure that you have a projected file.

An image would help as well of the area and the table

[GlynisHumphrey]

Yes, projected data. Please see image of spreadsheet below and output of (.swm).

Parameters used: Fixed_Distance /Euclidean

Threshold distance of 4500 m (decision based on the output of ''calculate distance band from neighbor'' (based on 8 neighbours).

OBJECT_ID Northing Easting FRP UNIQUE1_ID 1 8000825,818511 676948,741990 150 1 2 8000480,308070 678427,684079 236 2 3 8000721,842627 676206,759889 165 3 4 8000375,425250 677791,554651 136 4 5 8001061,488425 675362,908257 88 5 6 8002041,327851 677171,487260 63 6 7 8015891,633053 615645,426354 36 7 8 8004444,952169 692229,313859 28 8 9 8015547,751748 617655,792684 25 9 10 8015775,358381 616597,988187 22 10 11 8001356,018412 679494,357670 54 11 12 8015775,358381 616597,988187 22 12 13 8015547,751748 617655,792684 25 13 14 8004444,952169 692229,313859 28 14

Field1	UNIQUE1_ID	NID	WEIGHT
0	7945	818	1
0	7945	13443	1
0	7945	11107	1
0	7945	3721	1
0	7945	7961	1
0	7945	11104	1
0	7945	11108	1
0	7945	7984	1
0	7961	11107	1
0	7961	13443	1
0	7961	5875	1
0	7961	3721	1
0	7961	833	1

Thanks Dan.

[DanPatterson_Retired · Accepted solution]

Well...from the help file

At the most basic level, there are two strategies for creating weights to quantify the relationships among data features: binary or variable weighting. For binary strategies (fixed distance, K nearest neighbors, Delaunay Triangulation, contiguity, or space-time window) a feature is either a neighbor (1) or it is not (0).

[GlynisHumphrey]

Many thanks Dan. I was concerned as all the feature points have neighbours in that case - as there are no 0. Will double check.

[DanPatterson_Retired]

You might want to check your threshold distance then or try another model.  Post a map of your distribution if you want.

[DanPatterson_Retired]

Glynis, could you mark this question by checking the answer that worked, or assumed answered or convert to a discussion.  Threads with closure indicate the status and are useful to others when looking for help on similar topics.

[GlynisHumphrey]

Hi Dan - thanks. Here is the distribution map - succeeded in generating a .swm - I verified my data based on a re-run of my data in GeoDa software and the same patterns emerge. Thanks for you help.