Latest Contributions by PriscillaCoe

‎08-17-2015

Thank you for your suggestion. I would have to tweak the Fortran code, plus I don't have a compiler, plus I'm lazy.

‎08-17-2015

Thank you for your replay, Dan. It's not quite so straight forward. There is no header file, although I did get a suggested header file from their tech support. The problem is that each month of the year is included in one download file, so I think I need to read it in and write out each month to a separate file. They supply the Fortran code to read it, and I can do that, but I was wondering if anyone else has done it yet. Thanks again!

‎08-13-2015

I want to import grids from the Candadian Meteorological Centre to ArcGIS but it looks like some processing of each file will be needed. I'm wondering if anyone has developed scripts to read these files and prepare them for ASCII to Raster import? Here is the link: Data Set Landing Page Thanks for any help! Cilla

‎08-28-2013

I think this is where you get to use your judgement and use the classification method that's practical for defining your study areas. You have done the work of identifying the high density areas using an objective approach (showing that the data are clustered and using point density or kernel to identify the areas). Now it seems you can decide which classification method makes sense for your study, and be consistent if there will be more data in the future.

‎08-28-2013

Is it appropriate to run a Hot Spots analysis on linearly referenced features (I want to find deer-vehicle collision hotspots on a highway and so I have 100-m segmented road with the number of collisions as events). The tool allows it but I am not sure whether the underlying assumption of randomly located collisions is being applied to only the linear features rather than the entire space within the extent of the linear features. In other words, is the tool detecting clusters merely because the collisions can only be on the linear feature (ie they cannot occur off-road) or does the tool "know" that the events can only occur on the linear feature? I like the results I am getting but not sure about the underlying assumptions. Thanks for any insights! Cilla

‎05-31-2013

I have mule deer-vehicle collision data on highways. Is it appropriate to use these tools on a road network? It seems the underlying assumption of randomness would be applied across the extent of the highway not just on the highway. If so, any pattern of accidents would look non-random to the program. I have heard about the SANET toolbar that calculates these statistics for networks, but I'm not sure if I have to go there or not. Does anyone know?

‎05-31-2013

Hi Cilla, Thanks for your reply. I've been digging through some papers, and I largely came to the same conclusions you have. An excellent piece of citable research that helps explains some of the benefits of the Getis-Ord Gi* (and some of the negative aspects of the Moran's I), is Braithwaite and Li (2007), "Transnational Terrorism Hot Spots: Identification and Impact Evaluation." The discussion is largely on pages 285 - 287. I wish ArcGIS were a little more clear on the pros and cons of each tool, especially given how more and more disciplines are adapting geospatial analyses for their research. Thanks, I'll look at that. It is confusing to decide which tool to use. I did take a webinar course last week that helped sort it out.

‎05-23-2013

I am in the same boat so let's work on this together. From what I understand, there are global spatial statistics and local spatial statistics. The global ones, such as Moran's I or Getis-Ord Gi (without the *), capture global clustering and hotspots for the entire region of your dataset, whereas the local statistics such as Getis-Ord Gi* capture the local clustering and hotspots better. Kernel density is another way of capturing density or space-use. Kernel density is non-parametric meaning it doesn't identify statistically significant hotspots.

‎02-07-2012

We want to know the mean distance of the purple squiggly lines to the yellow straight lines (see attached). Just one mean distance to the nearest straight line. Do I need to convert the straight lines to points first? Cilla

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My Ideas

Latest Contributions by PriscillaCoe

Re: Monthly average snow depth files

Re: Monthly average snow depth files

Monthly average snow depth files

Re: point or kernel density but which classification method?

Hot Spots on linear features appropriate?

Spatial Statistics for roads

Re: Getis-Ord Gi* Benefits and Strengths

Re: Getis-Ord Gi* Benefits and Strengths

mean distance from helicopter track to transect line