GEOG 566






         Advanced spatial statistics and GIScience

Archive for May, 2017

May 26, 2017

A space for time substitution on an impacted landscape

Filed under: Tutorial 2 @ 1:49 pm

Question: Has the total daily energy flow through a functional group at a given elevation changed over the eighty-year interval between 1931 and 2011? Background: I am hoping to better understand the forces structuring small mammal communities, specifically rodents, across space and through time. In this regard, I am using trap effort-standardized abundance data to […]

May 24, 2017

Tutorial 2: Identifying clustering with a geographically weighted regression

Question You Asked How much spatial clustering is present in the regression model of vegetation response to canopy cover? I am interested in determining if a single equation can predict the way that the two variables interact within east-side ponderosa pine forests, or if multiple equations are necessary. Name of Tool or Approach You Used […]

Automating Feature creation of variables for explaining patterns of Socio-demographic and spatial variables of survey responses regarding flood-safety in neighborhoods

Filed under: Tutorial 2 @ 12:04 pm

Question asked As reported, I am handling more than 100 variables. In addition, my data is constantly being updated. So, I needed to be able to have a tool in order to create independent features for analyzing each of my variables. The question is: How can I automate Feature creation of variables for explaining patterns […]

Tutorial 2:

Filed under: 2017,Tutorial 2 @ 11:59 am

Research Question Building upon my question from exercise 2, my research question for exercise 3 seeks to answer how the covariance between SCF and EVI within a wildfire perimeter change over time following the wildfire. Approach/tools used For this exercise, I utilized a variety of software programs. While the overall goal of variogram creation required […]

Tutorial 2: Nitrate Data in Relationship with Red Alder cover and Land Use

Filed under: 2017,Tutorial 2 @ 11:43 am

  Research Question  Do the nitrate values that I collected in the field have a relationship with the percent of Red Alder cover in each watershed?                 Sub question: Do the nitrate values have a relationship with land use activities in each watershed tree? Name of the tool […]

Spatial autocorrelation in NDVI for wheat fields and some characteristics

Filed under: 2017,Tutorial 2 @ 11:06 am

Tutorial 2 is based on tutorial 1 with a few alterations. 1) the variogram is standardized by dividing the semivariance by the standard deviation of that field, 2) only the wheat fields are used for the analysis so that the results are more easily compared, and 3) a time component is added; for 5 time […]

Manipulating Layer Properties in ArcGIS ArcMap 10.4.1

Filed under: Tutorial 2 @ 1:09 am

Reva Gillman Tutorial 2                                Manipulating Layer Properties in ArcGIS ArcMap 10.4.1 Question that I asked: What are the geographic distributions of some of the ‘riskier’ species that arrived on Japanese Tsunami Marine Debris (JTMD)? What do their native and non-native ranges look like, and how do they compare with each other? First of all, I […]

May 23, 2017

Tutorial 2: Extracting raster values to points in Arc for regression analysis in R

Filed under: Tutorial 2 @ 10:38 pm

Research Question As I have described in my previous blog posts, I am investigating the spatial relationship between blue whales and oceanographic variables in the South Taranaki Bight region of New Zealand. In this tutorial, I expand on the approach I took for tutorial 2 to quantify whether blue whale group size can be predicted […]

Tutorial 2: Using kernel density probability surfaces to assess species interactions

Filed under: Tutorial 2 @ 4:48 pm

Overview: question clarification and approach Continuing my exploration of changes in cougar predation patterns in time periods with and without wolves, I wanted to expand my evaluation of spatial repulsion and/or shifts to examine how cougar kill site distributions related to wolf activity. I identified several elements in my data sets, besides the presence of […]

Tutorial 2

Filed under: 2017,Tutorial 2 @ 3:50 pm

For exercise 3, I finally left the world of Arc and took my data to R. Question/Objective: Test the radar backscatter between different-facing aspects and determine if aspect influences radar signal. Tool used: I used R to run the statistical analysis, but still needed to extract the data using Arc. What I did: I extracted […]

Tutorial 2: Investigate Spatial Autocorrelation (Mantel Test)

Filed under: 2017,Tutorial 2 @ 1:30 pm

For this Tutorial I revisited a principle that I learned about in the Spatio-Temporal Statistics (Variation) statistics course that I took with Dr. Jones last fall. Autocorrelation is an important component to address within ecological work, as well as geographic work. Plots that are closer to each other may have a greater probability of capturing […]

May 22, 2017

Tutorial 2: Site Suitability

Filed under: Tutorial 2 @ 2:43 pm

Question/Objective: For exercise 3, Dr. Jones allowed me to work on a big component of one of my thesis chapters that I needed done which was to determine site suitability for a field experiment. This wasn’t related to stats but required a lot of work in ArcMap. My questions are: Are forest meadows reptile biodiversity […]

Tutorial 2: Examining Hydrograph Relationships

Filed under: 2017,Tutorial 2 @ 2:12 pm

Question How does upstream-downstream connectivity, drainage area, and position within the catchment affect the relationship between different stage gage sites? Tool/Approach I chose to look at the relationships between the hydrographs for four sites that have upstream-downstream connectivity but have different upstream drainage areas and are located on different tributaries. I used ArcGIS to obtain […]

Tutorial 2: Automated Autocorrelation of Tsunami Inundation Time Series at Various Points of Interest

Filed under: Tutorial 2 @ 12:11 pm

Question Tsunami inundate shorelines in a chaotic manner, resulting in varying degrees of flooding from location to location. The spatial variability of tsunami hazards has important implications for the tsunami-resistant design of structures and evacuation plans because different safety margins may be required to achieve consistent reliability levels. Currently, tsunami mitigation strategies are primarily informed […]

May 21, 2017

Geographically Weighted Regression (GWR) in R

Filed under: 2017,handy links @ 10:18 pm

I found an interesting link about Geographically Weighted Regression (GWR) analysis in R. I think it might be useful. https://rstudio-pubs-static.s3.amazonaws.com/44975_0342ec49f925426fa16ebcdc28210118.html

Geographically Weighted Regression Analysis of Tropical Forest

Filed under: 2017,Tutorial 2 @ 10:10 pm

Question that you asked Is crown width linearly related to height in space in the study area? Name of the tool or approach that you used. I use Geographically Weighted Regression (GWR) tool in ArcMap to assess the linear relationship between crown width and height in space in the study area. Since the data has […]

Tutorial 2: Calculate Disturbance Severity Patch Sizes with SDMtools in R

Filed under: Tutorial 2 @ 4:29 pm

Overview Often patch dynamics are examined under the lens of single disturbance events, but contemporary disturbance regimes are demonstrating that large-scale disturbances can overlap in time and space.  The spatial configuration of patches from an initial disturbance may influences the spatial configuration of patches of a sequential disturbance.  The broader research question is focused on […]

May 8, 2017

Tutorial 1: Nitrate Concentration Differences: Between Sites and Over Time

Filed under: 2017,Tutorial 1 @ 10:26 am

Research Question:  Do the differences in nitrate concentrations indicate a pattern between site locations, and do they show a pattern over time. Tools and Approach:  I performed the analysis largely in excel, though ARC GIS mapping software was useful in spatial proximity analysis. I was able to produce a chart and representative scatter plot of […]

May 7, 2017

Tutorial 1: Visual data analysis

Filed under: Tutorial 1 @ 11:30 pm

Reva Gillman Geog 566 Research question: What is the geographic distribution of the native regions of the Japanese Tsunami Marine Debris (JTMD) species? Which regions are the most prevalent for JTMD species to be native to, and which are least prevalent? Approach that I used: visually represent native region frequency of JTMD species within 12 […]

Spatial autocorrelation in NDVI for agricultural fields vs the average biomass of that field

Filed under: Tutorial 1 @ 4:29 pm

  Question that you asked… Looking at the spatial autocorrelation of NDVI within a field and the average wet biomass of that field, is there a correlation? When the NDVI distribution is patchy, is the biomass lower? Or maybe higher? Or is there no relation at all. Name of the tool or approach that you […]

May 6, 2017

Forest Structure Assessment Using Variogram in R

Filed under: 2017,Tutorial 1 @ 8:16 am

Question and tool The questions that I try to answer in tutorial 1 is how the height and crown width vary in space in the study area, whether those variables are autocorrelated. I use variogram analysis in RStudio to answer these questions. The variogram is defined as the variance of the difference between field values […]

May 5, 2017

Tutorial 1: Use of the Optimized Hot Spot Analysis for explaining patterns of Socio-demographic and spatial variables of survey responses regarding flood-safety in neighborhoods

Filed under: Tutorial 1 @ 11:52 pm

1. Question Asked How socio-demographic and spatial variables explain patterns of survey responses about perceptions and attitudes regarding flood-safety in neighborhoods? Location of survey responses and variable values (variable: “perception of flooding reaching your home”) are shown in Figure 1.1. Figure 1.1. Location of survey responses and variable values (variable: “perception of flooding reaching your […]

Tutorial 1: Calculation, Graphing, and Analysis of Correlation Coefficients in Excel

Filed under: 2017,Tutorial 1 @ 2:27 pm

Question: How well correlated are stage gage data at different locations within a single basin, based on the amount of distance between them? Approach: To explore this question, I used the Correlation function in Excel to do a pairwise correlation analysis of my six sets of stage gage data, and then correlated the results with […]

Tutorial 1: Raster auto correlation in R

Filed under: Tutorial 1 @ 1:47 pm

A Quick Primer My spatial question is how the radar backscatter (measured by the Sentinel-1 satellite) relates to features on the ground. The backscatter is influenced by slope, aspect, forest characteristics (tree height, density, moisture content etc.) The question I was asking for the first excercise was whether or not my backscatter was autocorrelating. If […]

May 4, 2017

Tutorial 1: Using a Geographically Weighted Regression to assess the spatial relationship between blue whales and chlorophyll-a

Filed under: 2017,Tutorial 1 @ 4:41 pm

Research Question The goal of my spatial problem is to assess the relationship between blue whales in the South Taranaki Bight region of New Zealand and the environmental factors which define their habitat and influence their spatial distribution. Chlorophyll-a (chl-a) concentration is an indicator of productivity in the marine environment. Chl-a can be remotely-sensed, and […]

Tutorial 1: Using Logistic Regression vs Ordinary Least Squares Regression.

Filed under: Tutorial 1 @ 3:04 pm

Question: How is chytrid fungus presence/absence related to the distance from road or trail? I chose this question because humans are known to be one of the primary causes of pathogen transmission. This question involves a relationship between presence or absence of chytrid fungus (dependent variable) and distance from road or trail (explanatory). Tools: I […]

May 3, 2017

Tutorial 1: Cross-Correlation between tsunami inundation time series extracted from gridded netCDF data

Filed under: Tutorial 1 @ 12:44 pm

Question Tsunami inundate shorelines in a chaotic manner, resulting in varying degrees of flooding from location to location. The spatial variability of tsunami hazards has important implications for the tsunami-resistant design of structures and evacuation plans because different safety margins may be required to achieve consistent reliability levels. Currently, tsunami mitigation strategies are primarily informed […]

May 1, 2017

Tutorial 1: Assessing distribution shifts in kernel density probability surfaces

Filed under: Tutorial 1 @ 1:48 pm

Overview: question & approach Identifying spatial repulsion and/or shifts in distribution are often examined to identify interspecific competition effects. Therefore, I wanted to assess the distribution of cougar kill sites including the spatial clustering and frequency in pre- and post-wolf time periods focusing on identifying shifts. A simple solution to my presence only data (kill […]

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