Hi,

I am running the hot spot analysis to identify clusters of high and low areas of respiratory diseases. I have watched several esri videos about the topic and in an earlier video it talks about running moran's i autocorrelation to select a suitable distance band, in a more recent video I have watched it talks about calculate distance band and incremental spatial autocorrelation (ISA). I realise they both produce Moran's i z scores but I have run both and get different results so I am not sure which one is better to use. The results from ISA seem to be suggesting higher distance bands (peaking at higher distance values) which means by data is showing large hot spots (more like trends), where as the running Moran's i I see peaks in lower values which produces smaller hot spots.

Would it be acceptable to use the calculate distance band and just use the maximum value in Moran's i as this produces a peak in the z score at a smaller distance. For example, the maximum distance is 2.09736dd, and the average is 0.368413dd. Results in ISA peak at 5.04dd and Moran's peaks at the 2.09dd value. Also, the conceptualisation of spatial relationships is to be the same as I am using in the hot spot analysis, yes?

Thank you.

I am running the hot spot analysis to identify clusters of high and low areas of respiratory diseases. I have watched several esri videos about the topic and in an earlier video it talks about running moran's i autocorrelation to select a suitable distance band, in a more recent video I have watched it talks about calculate distance band and incremental spatial autocorrelation (ISA). I realise they both produce Moran's i z scores but I have run both and get different results so I am not sure which one is better to use. The results from ISA seem to be suggesting higher distance bands (peaking at higher distance values) which means by data is showing large hot spots (more like trends), where as the running Moran's i I see peaks in lower values which produces smaller hot spots.

Would it be acceptable to use the calculate distance band and just use the maximum value in Moran's i as this produces a peak in the z score at a smaller distance. For example, the maximum distance is 2.09736dd, and the average is 0.368413dd. Results in ISA peak at 5.04dd and Moran's peaks at the 2.09dd value. Also, the conceptualisation of spatial relationships is to be the same as I am using in the hot spot analysis, yes?

Thank you.

I too had challenges with the ISA tool. If I remember right ISA works by calculating Moran I with increasing neighbourhood sizes. Meaning Moran is calculated at each of the increments you set ex 10km 20km 30km etc. This means that each band is calculated with a different number of neighbours. My first band could have 3 neighbours and my last band could have 500 neighbours, this produced very spikey results in near bands and better results as the number of neighours increased, so you need to consider this in interpreting your results. I ended up ignoring all my moran values until a couple distance bands away from the origin.

Depending on the parameters you used to perform the single Moran the value should be the same at the same distance band in the ISA tool. Ie if you set the distance band in the moran tool to 100 and the ISA had the same band value the moran values should be the same.

Also, I see that you quoted your distance in dd. As Moran I is supposed to be calculated in flat space (cartesian) x and Y I would suggest projecting your data to projected coordinate system.

David