The spatial tag has no wiki summary.
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0answers
28 views
Hilbert curves: bounds / probabilities of preserving neighbors
Hilbert Curves (Wikipedia) are space-filling curves said to "fairly well preserve locality".
Do you know any theoretical results here, such as bounds that neighbors within a radius of $\varepsilon$ ...
0
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0answers
29 views
regression: handling negative autocorrelation in R?
I am running a regression in the R package nlme (but am not constrained to only that package). I am changing the spatial scale of the analysis over a few regression runs as a form of sensitivity ...
1
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1answer
36 views
Ripley's K Function and L Function for Point Patterns
The following is a spatial point pattern:
and these are the corresponding Ripley's K function and L function for this data:
How are these functions interpreted?
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1answer
40 views
Tests for spatial stationarity (homogeneity)
There are many models for spatial point patterns and spatial marked point patterns that assume spatial homogeneity or stationarity.
i) Is there a statistical test for determining this, where the ...
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0answers
24 views
account for spatial autocorrelation with a binomial regression model
I am using a binomial regression model for presence/absence, with 20 independent variables to test. The data has x and y coordinates and I would like to understand how can I take into account the ...
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0answers
89 views
Pros and Cons of Fitting a Spatial Regression to Cumulative Data
When using regression to estimate a relation between a variable of interest and distance from a certain point (eg a distance-decay curve), what are the advantages and disadvantages of fitting the ...
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2answers
99 views
spatial autocorrelation for time series data
I have a 20-yr dataset of an annual count of species abundance for a set of polygons (~200 irregularly shaped, continuous polygons). I have been using regression analysis to infer trends (change in ...
3
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1answer
145 views
Hypothesis test on data with confounding spatial clustering
This is a bit of an elaboration on a question I posted earlier, since I feel like my approach to the problem as a whole is probably quite flawed.
Suppose I have a set of treatment and control cells, ...
2
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1answer
39 views
Filtering outliers from geo-spatial-temporal log
I have downloaded my Latitude location history from Google for the time of about three years and now I'd like to, for starters, visualize where I've been.
It turns out that the history contains some ...
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0answers
35 views
Measuring distance between geographic coordinates among other variables
I am setting up a quasi-experimental design and I need to compare each treatment account to all potential control accounts within a certain geographic region. I would like measure the distance ...
1
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0answers
39 views
Modeling spatial correlations with multilevel data
I have ~5M records of spatial polar coordinates (r and theta). These 5M records are from 400 different 'locations' that I have ~150 variables for (no NAs). I also have 1 binary variable used to flag ...
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0answers
41 views
Dealing with bias when aggregating spatial data
I've got a situation where I'm interested in $\Delta Y_{xy}$. This is calculated as $\Delta Y_{xy} = Y_{xy} \times change_{xy}$. Everything is vector-valued. I've got vector data on $change_{xy}$. ...
4
votes
1answer
98 views
Are there models for “censored” spatial point processes?
This is a problem I'm encountering in the context of analyzing a data set comprised of all crime locations in a city over a fixed time interval, although it could potentially arise in other types of ...
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2answers
60 views
How to analyse several types of geo data together?
I have some data gathered from a survey conducted within my city. All responses include an approximate geo location of where they were gathered (accurate to probably a couple of hundred yards which is ...
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1answer
70 views
How to distribute symbols uniformly in a square grid? [closed]
Given a square grid of size $n\times n$ and $m$ symbols (say for example, alphabets A, B, C...), having $N(i)$ number of $i$th symbol; $\sum_{i=1}^{m}N(i) = n\times n$. Is there any algorithm that can ...
1
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1answer
33 views
Help me figure out the profile likehihood given this covariance function
I'm taking a spatial stats class, and I'm on the road so I can't ask the prof for help. Would appreciate help understanding what is going on here.
The problem is set up with $Y = X_s'\beta + e$ ...
3
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0answers
104 views
Spatial autocorrelation of non-homogeneous point data in irregularly shaped sample plots
Let's assume we registered the position of all individuals of different plant species within 3 irregularly shaped sample plots that are very close the each other. As an example, I put 2 pictures with ...
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0answers
61 views
Generating data using grf and plotting its variogram- Result intrepretation
I have a question about the semivariogram plot:
Suppose I generated 50 data points from Gaussian random field (using grf function in R), and assumed that we have exponential covariance model with ...
3
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2answers
153 views
Using Anselin Local Moran's I Values in Regression
I am doing a multiple linear regression of factors related to poverty and would like to include some spatial-statistical data. I have come up with Anselin Local Moran's I values (cluster/outlier) data ...
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1answer
131 views
Suggested books on spatial statistics
What are some of the best books for studying
i) variability of univariate and multivariate variables (real, count data) across a spatial domain.
ii) sampling a univariate or multivariate variable ...
1
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0answers
29 views
Possible outcomes of approximate profile-likelihood estimator (APLE) for spatial autocorrelation
I've been working with spatial autocorrelation for a while and now I'm trying to move from more traditional estimators such as Moran's I or Geary's C to the new APLE estimator. I read Li's papers on ...
4
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0answers
140 views
Spatial autocorrelation versus spatial stationarity
Let's assume we have points in two-dimensional space, and we wish to measure the effects of attributes $X$ on attribute $y$. The typical linear regression model is of course
$$y= X\beta + \epsilon$$
...
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0answers
40 views
How do I extend Inverse distance weighting to take into account uncertanities?
From a Multibeam echosounder (MBES) I have n x m measurements:
{(xi,yi,zi,di)}_i where (xi,yi,zi) is the location of the i'th reflection from the seafloor and di is the distance of the i'th reflection ...
3
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2answers
134 views
Auto crop black borders from a scanned image by making stats about gray values
I'm writing a computer program to automatically detect black noisy borders on scanned images and crop them off.
My algorithm is based on 2 variables: gray mean value (of the pixels in a rows/columns) ...
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0answers
74 views
Confusion related to bayesian spatial scan statistics
I was reading this paper related to bayesian spatial scan statistics. http://books.nips.cc/papers/files/nips18/NIPS2005_0513.pdf. It's said that when we use bayesian spatial scan statistics, we don't ...
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0answers
184 views
How to specify in r spatial covariance structure similar to SAS sp(pow) in a marginal model?
I'm currently translating existing code from SAS to R. I'm working on longitudinal data (CD4 count over time). I have the following SAS code :
...
2
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1answer
51 views
MLE estimation of spatial effects radius
I am trying to identify the maximum likelihood estimates in an SDM model (a hedonic home price model, with observations being 5,000 individual homes),
$$y=\rho W y + X\beta + WX\lambda + \epsilon$$
...
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0answers
26 views
Problems with spBayes package and prediction
I have successfully fit a number of spatial models with spBayes and am now trying to test their out of sample predictions. However spPredict always seems to fail with Cholesky decomposition errors. ...
1
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1answer
113 views
GLM and GAM package alternative to GRASP in R?
I am looking for the best package providing Generalized Linear Models (GLM) and General Additive Models (GAM) for spatial data. The most widely recommended (GRASP) is no longer current in the ...
2
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0answers
157 views
Compute Moran's I or some other estimate of spatial correlation in R
I'm trying to do a little spatial analysis--just some simple spatial correlations. I have a data frame consisting of latitude and longitudinal points, a value to model, and a neighborhood indicator. ...
5
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1answer
122 views
Computing confidence region for Gaussian mixture model
I have a 2-d Gaussian mixture model and would like to compute a confidence region for it. Our application is that the two dimensions are latitude and longitude; that is, we want to say something like ...
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0answers
12 views
Test for two - dimensional uniform distribution? [duplicate]
Possible Duplicate:
Measure the uniformity of distribution of points in a 2D square
I have spatial data -coordinates on rectangle, how to test if they come from two dimensional random ...
2
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1answer
51 views
Which metric use for problem of clustering spatial data of wind direction and speed?
I have two dimensional spatial (x,y - coordinates of meteo stations) data for small region (so I could neglect the shape of earth globe), for each (x,y) I have one observation of wind direction and ...
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3answers
453 views
Measure the uniformity of distribution of points in a 2D square
I have a 2D square, and I have a set of points inside it, say, 1000 points. I need a way to see if the distribution of points inside the square are spread out (or more or less uniformly distributed) ...
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3answers
197 views
Clustering with 3 attributes
Please bear with me because I am very new to data mining.
I have a database of 3 attributes: latitude, longitude and temperature. I want to find clusters for the temperature data and I also want to ...
2
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1answer
107 views
Generating spatially uncorrelated random fields in R
I have a DEM (cellsize 10x10 and cells.dim 450x300)
and I need to create 100 random error grids
that have the same dimensions as the DEM.
The values in the error grids are generated from a
normal ...
2
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0answers
63 views
Calculating R-squared values from a semivariogram
I have some spatially autocorrelated vegetation data, and would like to know the how well tree size measured at one location can predict tree size in plots 100m away.
I've made a semivariogram of ...
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3answers
210 views
Regression discontinuity versus matching with spatial discontinuity
I am interested in using a spatial research design. Imagine a line, like a time zone line. For example, in the United States, the line that makes between Eastern Standard Time and Central Standard ...
5
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1answer
167 views
Testing for Spatial Autocorrelation in a Negative Binomial Regression Model
Currently, I am working on a count data set measuring events in a third-order administrative unit. The frequency of events varies for each third-order administrative unit to account for the ...
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0answers
39 views
What is the best model for valuation of credit vintages?
I would like to find the best way to estimate the effect of several factors on complex data set of credit vintages. This data actually has two time dimensions and several categorical variables. ...
2
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1answer
288 views
What to use, k-means or hierarchical clustering for presence absence data?
I am currently working with a presence-absence database that is mostly zeros (~5% are ones) representing species in space (a species per site matrix). I would like to explore the spatial pattern of ...
4
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0answers
77 views
Spatial interpolation of vectors in vector fields
Statistical modeling is new to me and I would appreciate some thoughts on my project. I am trying to model the spatial (and possibly temporal as well) relationships within vectors in vector fields. ...
3
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1answer
133 views
How to display concentration data in space?
I have a data frame of chemical concentrations that are measurements taken from 12 locations all in the same vicinity. I have manually assigned x and y coordinates to each location (on a 0 to 20 ...
1
vote
1answer
134 views
Discrepancy between lagged lm() and lagsarlm()
If we have a spatial autoregressive process, we can estimate a model to control for the autoregression with a spatial lag,
$$y=\rho W y + X\beta + \epsilon$$
Where $\rho$ is the strength of the ...
4
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0answers
59 views
Regressing on many outcomes in a spatial model
I'm measuring many microbe populations in a 'river model' ecosystem by sampling at two points. I want to test the hypothesis that key species upstream are the best predictors for any given population ...
2
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1answer
196 views
How to report the standard deviation of a sample of averages?
If you have a 100x100 grid of values and you want to report the standard deviation of an area that takes up a 20x20 portion of the grid, this is not problem. But what is the correct way to calculate ...
3
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1answer
77 views
Interpretation of spatial Gcross plots
On page 192 of Analysing spatial point patterns in 'R' (Baddeley 2011), there are plots of the Gcross function for the amacrine dataset. I am looking for an interpretation of the plot. off/off and ...
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0answers
41 views
Help with designing the analysis of a radio telemetry study
I was wondering if there are any spatial ecologists out there who can provide some insight on the trouble I'm having with my Masters research.
I am looking at the association a bat species to high ...
5
votes
1answer
362 views
Linear Regression and Spatial-Autocorrelation
I want to predict Tree Heights in a certain area using some variable obtained through remote sensing. Like approximate Biomass, etc. I want to first use a linear regression (I know it's not the best ...
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0answers
82 views
Singular covariance matrix and Spatially-correlated random effects [closed]
I'm interested in incorporating spatially-correlated random effects into my model to explicitly account for between-observation spatial autocorrelation, such that spatial autocorrelation decreases ...
