GEOSTATS: test for uniform planting site?
- You can use a KNN (Kth Nearest Neighbor) bootstrap. Perform the
following (considering your example):
1) let knn = sqrt(30) = 5 or 6 (you may define any other value)
2) Visit the 30 locations along a random path
3) At location i, consider the nearest 6 points. Calculate a re-sampling
probability of each of these 6 points such that the closer the point to
point i, the higher the probability. (use the inverse distance and
normalize, or use Kernel function)
4) Re-sample point i according the probabilities caclulated above
5) proceed along the random path to re-sample all points and obtain 1
6) repeat many times with different random paths (10000....).
7) Calculate the fraction of F, and S (if you are working with growth
height, you can categorize it) from the obtained realizations.
A. Ali, Ph.D., P.E.
New Mexico State Engineer Office
P.O.Box 25102, Santa Fe, NM 87504
e-mails: aali@...; or aali@...
Phone: 505-827-6125 Fax: 505-827-6188
> I am looking for a test that planting locationand
> influences seedling growth. For example,
> 30 seedlings are planted in a uniform medium.
> The S represent "slow growers" and the F
> represent "fast growers".
> F S S F S F
> F F S F S S
> S S F S F S
> S S S F S F
> F S F S F S
> The above is a simplified example as
> I have height growth for each seedling
> and about 600 seedlings.
> One approach would be a jacknife or bootstrap
> type approach of randomly assigning each seedling
> growth to each location and repeating the randomiztion
> trials 1,000 times. Then compare the original distribution
> with the 1,000 randomization trial distributions. But
> The null hypothesis is that the site is uniform and
> all variablity of seedling growth is due to factors
> other than seedling location.
> Any suggestions would be appreciated. I will post
> a summary on April 15, 1997.
> Thank you.
> Dave Verbyla
> Associate Professor of GIS/Remote Sensing
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