3182 search results for "GIS"

Logistic Regression in R – Part Two

September 2, 2015
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Logistic Regression in R – Part Two

My previous post covered the basics of logistic regression. We must now examine the model to understand how well it fits the data and generalizes to other observations. The evaluation process involves the assessment of three distinct areas – goodness of fit, tests of individual predictors, and validation of predicted values – in order to

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Logistic Regression in R – Part One

September 1, 2015
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Logistic Regression in R – Part One

Please note that an earlier version of this post had to be retracted because it contained some content which was generated at work. I have since chosen to rewrite the document in a series of posts. Please recognize that this may take some time. Apologies for any inconvenience.   Logistic regression is used to analyze the

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Searching Twitter with ArcGIS Pro Using R

August 18, 2015
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Searching Twitter with ArcGIS Pro Using R

I committed to testing this a long time ago, however, a number of other projects intervened, so I have only just got around to writing up this short tutorial. One of the exciting things from the ESRI Developers Conference this year was the launch of the R-ArcGIS bridge. In simple terms, this enables you to run R...

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Evaluating Logistic Regression Models

August 17, 2015
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Evaluating Logistic Regression Models

Logistic regression is a technique that is well suited for examining the relationship between a categorical response variable and one or more categorical or continuous predictor variables. The model is generally presented in the following format, where β refers to the parameters and x represents the independent variables. log(odds)=β0+β1∗x1+...+βn∗xn The log(odds), or log-odds ratio, is defined

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Empirical bias analysis of random effects predictions in linear and logistic mixed model regression

July 30, 2015
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Empirical bias analysis of random effects predictions in linear and logistic mixed model regression

In the first technical post in this series, I conducted a numerical investigation of the biasedness of random effect predictions in generalized linear mixed models (GLMM), such as the ones used in the Surgeon Scorecard, I decided to undertake two explorations: firstly, the behavior of these estimates as more and more data are gathered for each

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Roll Your Own Gist Comments Notifier in R

July 25, 2015
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As I was putting together the coord_proj ggplot2 extension I had posted a (https://gist.github.com/hrbrmstr/363e33f74e2972c93ca7) that I shared on Twitter. Said gist received a comment (several, in fact) and a bunch of us were painfully reminded of the fact that there is no built-in way to receive notifications from said comment activity. @jennybryan posited that it

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Logistic Growth, S Curves, Bifurcations, and Lyapunov Exponents in R

July 24, 2015
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Logistic Growth, S Curves, Bifurcations, and Lyapunov Exponents in R

If you’ve ever wondered how logistic population growth (the Verhulst model), S curves, the logistic map, bifurcation diagrams, sensitive dependence on initial conditions, “orbits”, deterministic chaos, and Lyapunov exponents are related to

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Hadley Wickham’s Master R Developer Workshop – Washington DC registration is open

June 12, 2015
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Hadley Wickham’s Master R Developer Workshop – Washington DC registration is open

“Master” R in Washington DC this September! Join RStudio Chief Data Scientist Hadley Wickham at the AMA – Executive Conference Center in Arlington, VA on September 14 and 15, 2015 for this rare opportunity to learn from one of the R community’s most popular and innovative authors and package developers. It will be at least another

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Simulation-based power analysis using proportional odds logistic regression

May 22, 2015
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Simulation-based power analysis using proportional odds logistic regression

Consider planning a clinicial trial where patients are randomized in permuted blocks of size four to either a 'control' or 'treatment' group. The outcome is measured on an 11-point ordinal scale (e.g., the numerical rating scale for pain). It may be reasonable to evaluate the results of this trial using a proportional odds cumulative logit

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R vs QGIS for sustainable transport planning

April 19, 2015
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R vs QGIS for sustainable transport planning

The 23rd iteration of the GIS Research UK conference (#GISRUK) conference was the largest ever. 250 researchers, industry representatives and academics attended from the vibrant geospatial research communities in the UK, Europe and beyond. GISRUK has become a centrepoint for discussion of new methods, software and applications in the field. I was on the organising committee, reviewed some excellent papers for the event (a full list...

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