topic Re: Spatial weight matrix error in Spatial Statistics Questions

Spatial weight matrix error

GlynisHumphrey — Fri, 20 May 2016 10:24:09 GMT

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.

Re: Spatial weight matrix error

DanPatterson_Retired — Fri, 20 May 2016 10:30:07 GMT

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?

Re: Spatial weight matrix error

GlynisHumphrey — Fri, 20 May 2016 10:34:39 GMT

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

Thanks.

Re: Spatial weight matrix error

DanPatterson_Retired — Fri, 20 May 2016 10:42:03 GMT

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

Re: Spatial weight matrix error

GlynisHumphrey — Fri, 20 May 2016 11:10:19 GMT

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.

Re: Spatial weight matrix error

DanPatterson_Retired — Fri, 20 May 2016 12:14:46 GMT

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).

Re: Spatial weight matrix error

GlynisHumphrey — Fri, 20 May 2016 13:11:45 GMT

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

Re: Spatial weight matrix error

DanPatterson_Retired — Fri, 20 May 2016 13:19:57 GMT

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

Re: Spatial weight matrix error

DanPatterson_Retired — Sun, 22 May 2016 02:46:19 GMT

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.

Re: Spatial weight matrix error

GlynisHumphrey — Tue, 24 May 2016 08:07:49 GMT

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.