Hi, I'm have some data on a grid (specifically high throughput assay plates)
and am interested in evaluating measures of spatial autocorrelation to flag
plates for corrections. I have been using moran.test and geary.test from the
spdep package.

My approach is as follows:

## plate is a matrix of data
coords <- expand.grid(1:32, 1:48)
x <- as.numeric(plate)
moran.test(x, nb2listw(tri2nb(coords)))

While this works and seems to give me reasonable results, I am not
specifying a weight matrix and am imposing a triangulation on my grid.
My questions are:

1. Has anybody done something like this before, in the context of high
throughput screening?
2. I'd like to specify that for a given well on the plate, it's nearest
neighbors will the N surrounding cells. How would I go about this?
3. Is the use of tri2nb correct for this type of application?

Any pointers would be appreciated

Thanks,

-- 
Rajarshi Guha
NIH Chemical Genomics Center

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