Questions tagged [spatial]

The field of study concerning statistical methods that use space and spatial relationships (such as distance, area, volume, length, height, orientation, centrality and/or other spatial characteristics of data) directly in their mathematical computations.

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Strength Parameter in ICAR Spatial Model

As I understand it, the parameter $\alpha \in [0, 1]$ that controls strength of spatial association in a CAR model gets set to 1 in an Intrinsic CAR model. Does this mean that an ICAR model cannot/...
646 views

How to specify a model with spatial correlation AND crossed random intercepts in R (nlme)

I want to model repeated measurements (let's say yearly) from multiple sites. Let's say after modeling these data with random intercepts for site and year we find there remains spatial correlation in ...
290 views

Moran's I test for spatial autocorrelation on the residuals from a logistic mixed model

I know that tests using Moran's I are not appropriate for binary outcome variables, but can I use that test on the residuals from a logistic mixed model to see if spatial dependence is unaccounted for?...
85 views

Anomaly detection with geo spatial data

I have geo spatial data. Dataset represents concentration of something. For instance, social media activity of people in point [time, lat, lon] I have some list of feature for every points (lat, lon):...
72 views

Test groups of spatially dependent data?

I have a set of ~100 forested natural reserves surrounded by multiple non-overlapping buffers of 100, 500, 1000 and 2000m. I would like to understand if there is a higher rates of disturbances in ...
54 views

T-test for paired differences of two time series of spatial averages with variable data counts

Suppose I have two 30-day time series consisting of spatial averages of some meteorological variable like global wind speed, for two experiments (over the same 30 days). Each day, there might be a ...
170 views

Statistical analysis of 3D coordinates and distances

I'm evaluating two different techniques of identifying the representation of the motor network within the brain. Both techniques identify the center of gravity of the motor network in MRI coordinates ...
25 views

Explicit form of the frobenuis norm of difference between the full matrix and its best rank approximation.

Suppose I have a Gaussian process regression $Y(s)= x(s)\beta +w(s) + \epsilon (s)$ where $w(s)$ is the spatial process and $\epsilon(s)$ is the nugget effect. I have a bit of difficulties ...
24 views

Cerioli's modified test of indepence with spatial data

I have to two datasets $X$ and $Y$ with binary observations on a regular grid. A regular contingency test for independence would be flawed by the presence of spatial autocorrelation. Cerioli (1997) ...
27 views

Noisy conditional simulation

A conditional random field $Z_C(x)$ is a random field whose realisations $z_C(x)$ always take the same values $z_C(x_a)$ at locations $x_a$. Realisations of $Z_C(x)$ can be produced as follows (...
251 views

Is the Matérn covariance function associated with the Matérn cluster process?

This question follows on from something I couldn't figure out in this question. Is there a relationship between the MatĆ©rn cluster process and MatĆ©rn covariance function beyond both being ...
56 views

How do Hidden Markov Models handle spatial data?

How do hidden markov models (HMMs) handle spatial data? I've seen papers where they divide the spatial area up into a grid and then model the order of the markov chain from left to right, down a row, ...
3k views

Ordinary kriging example step by step?

I have followed tutorials online for spatial kriging with both geoR and gstat (and also ...
229 views

What is the general idea of Spatial Cox Process?

I can't seem to understand the whole idea of Cox Process in spatial point pattern. Can someone explain it in layman's term? thank you
59 views

Spatial Regression of uniformly sampled KDE

I'm trying to formulate a spatial regression, and could do with some guidance. For my independent variable, I have multiple discrete observations, each with a latitude, a longitude, and a category. ...
37 views

Handling error with spatially lagged variable that is related to but distinct from outcome variable. SAR, CAR, Durbin, or lagged X?

I am estimating a diffusion model in which I am using spatial lags to predict an outcome variable, but I'm having trouble specifying the distribution of the error term because the lagged variable is ...
33 views

References on simulating a raster with spatial dependence

I've simulated an N-by-N raster in the following way: define a set $S$ containing a finite number $|S| = K$ of possible raster values (in my simulation, $K=3$ and the elements of $S$ are land uses / ...
371 views

How is Spatial Correlation for a normally distributed data related to spatial correlation of its logarithmic values

I have a lognormal spatially correlated dataset which has exponential correlation model with parameter l representing correlation length. Now we also have relations available to convert mean and ...
51 views

Similarity in the problems of using OLS with clustered and spatially autocorrelated data?

I understand that using a regression method that assumes independence of observations with an outcome that is either clustered or (positively) spatially autocorrelated can give misleading results. Let'...
6k views

What is the nugget effect?

I don't understand exactly what is meant by the term "nugget effect" in geostatistics. When looking at empirical variograms plotting the variogram $\gamma(h)$ vs. the lag $h$, the nugget is defined as ...
111 views

How to incorporate spatial correlation function into Linear mixed effect model in Matlab?

I have spatially correlated data which I want to fit in a linear mixed effect model In matlab. I use fitlmematrix model where there are only one co-variance structure to be included which is for ...
22 views

Determine if data in distance classes significantly different from linear regression

I'm trying to understand the relationship of some ecological data I have with geographic distance. Normally, the assumption is that this particular ecological data is linearly related with distance, ...
67 views

Are Kriging's residuals (i.e. $Z-\hat{Z}$) spatially independent?

Suppose data ${Z(s_i ):i=1, ..., n}$ are observed at spatial locations ${s_i :i=1, ..., n}$. To carry out the spatial prediction (predict un unknown $Z(s_0)$ at a known location $s_0$) we can use a ...
67 views

Spatial clustering analysis on binomial data collected on a grid

I am new to spatial statistics and need help figuring out how to assess if there is spatial clustering in my dataset using R. I am assessing if acorn consumption is different inside timber harvest ...
1k views

What is the difference between Kamb and 1% area contours?

I have been doing a bunch of spherical statistics using Stereonet and there is a function for producing contour plots of data density. One of the options in this function is a choice between Kamb ...
8k views

What is the rationale of the Matérn covariance function?

The MatĆ©rn covariance function is commonly used as kernel function in Gaussian Process. It is defined like this  {\displaystyle C_{\nu }(d)=\sigma ^{2}{\frac {2^{1-\nu }}{\Gamma (\nu )}}{\Bigg (}{\...
47 views

spatial non-stationarity, spatial durbin model “in differences” and bounds testing

I have two spatially correlated series. Basic tests indicate spatial non-stationarity of both, but no cointegration (Lauridsen & Kosfeld, 2006). Does anything speak against differencing all ...
635 views

what statistical test should i use for my count data?

i want to test the number of varroa mites in individual apiaries is higher in the south of england vs the north I'm working with count data (mites) and catergorical data (location) i used a ...
59 views

Extracting common sequences from time sequence data

I have a large number of time ordered location traces that I'd like to extract common sequences from. These locations are mapped from latitude, longitude pairs to a 2D aggregation bucket to handle ...
90 views

How much data do I need in spatial hotspot analysis?

I'm now doing a project about spatial hotspot analysis. I read many literatures, however, I can't find any papers tell how they determine the data size they used. I mean, suppose we have crime ...
93 views

Rate Smoothing in Spatial Data -

I asked this question on Reddit a few days ago but didn't get any responses. Working on some spatial epidemiology research a while back, that has resurfaced, I was told that I should smooth the ...
221 views

Convert Spatial Weight Matrix File?

I want to create a spatially lagged version of my response variable to estimate a spatial autoregressive model in R. To quantify the spatial relationship that exists among the features in my data I ...
1k views

How to test if these two samples are from the same distribution? [closed]

How to test if these two samples are from the same distribution? (These are tweets located near some tourist attractions. If yes, is there a simple implementation in Python?
47 views

If I have two samples of spatial distribution (tweets), how do I test if they're from the same distribution? [duplicate]

If I have two samples of spatial distribution (tweets), how do I test if they're from the same distribution? What are model is usually used to represent distribution of tweets? The data I have are ...
181 views

Mean of nearest neighbour distance in a clustered distribution

What would be the expected value of distances to the nearest neighbor in a set of points in 2-dim space that have a clustered (not random) spatial distribution? If the distribution is random the ...
24 views

Options for spatially correlated outputs (i.e. structured regression)?

I have a convolutional neural network which takes a 40x40 real valued input, and maps it to a real valued 40x40 output. I've optimized the number of convolution layers, filter size, hidden layer size, ...
123 views

Inferring locations from groupings of items

Let's say I have a large series of three-item bundles, like so: ...
1k views

Poisson distribution sampling in 2D space with spatially varying intensity?

I am sampling points from a Poisson process in a 2D space (Ny, Nx) grid with a constant intensity (lam) using the code given ...
74 views

Estimating the significance of the spatial distribution of several points within a single sample

I have a 100um x 100um x100um volume which has 200 cells in it. I will measure the locations of those cells within the volume, and wish to estimate whether they are significantly non-randomly ...
64 views

2D inferential mapping

I have a dataset that maps vein positions in the calf. This is a dataset of 14,000 (x, y) positional coordinates (one set of (x, y) per vein), using common anatomical landmarks. I have plotted these ...
148 views

How do you interpret this variogram?

Description: 8000 spatial data points spanned over an entire state 200 bins are used My question: Is the variogram telling something about the nature of the data? Why is it fluctuating? Should I do ...
139 views

What is the best procedure to detrend data without loosing its anisotropy?

I wand to detrend some spatial data "A" with respect to two parameter "B&C". What is the best procedure to detrend A without loosing its anisotropy. Theoretically values of "A" should be ...
549 views

How can I do a t-test on 2D data?

How can I do a t-test on 2D data with latitude and longitude attributes? I have 2 clusters of similar coordinates but in different time, I want to do a t-test to see if they are statistically ...
39 views

Extrapolating Hierarchical Time-Series Data

I have time-series data of national-level population estimates from 1990 to 2015. I also have subnational-level population estimates (thus, the distribution of national data), but only for years 2000 ...
54 views

How to choose the statistic metrics to describe the patterns of trees near the tree line?

I have tree inventory data: about 700 points of trees with known locations (X;Y;Z) and measured heights and diameters of stems at the breast height (DBH). The trees are located along the elevation ...
2k views

Moran's test using the residuals of logistic regression

I have fitted a logistic regression and I would like to check for spatial autocorrelation in the residuals of the model. Is it statistically correct to implement the Moran's test using the residuals ...
39 views

Algorithm that preserves the order of the predicted variable

Hi all, I need some advice on possible algorithms that I can apply to the following problem (if possible with pointers to implementations of these algorithms). The dataset: I have some dataset ...
38 views

Combine Correlations over globe to get overall correlation

I realize this question might be confusing, so I'd first like to explain my setup: Imagine you have the earth split into grids. At each gridpoint there is a vector, and let's imagine I have two ...
187 views

Distribution of distance to nearest (farthest) neighbour in normal data cloud

Here is an example of standard normal datasets (spherical, i.e. identity covariance matrices) in 1, 2, 3, 5, 10 dimensions, n=100 points. The picture shows observed ...