2697 search results for "GIS"

Legislative Activity in the Danish Parliament

December 22, 2011
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Legislative Activity in the Danish Parliament

As mentioned in this post, I have been using the powerful combination of the Beautiful Soup and Mechanize modules in Python to build a web scrapers. The amount of data on the web is amazing, and I believe that any quantitatively oriented social scienti...

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Logistic Regression Explained

December 1, 2011
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Logistic Regression Explained

Logistic regression is a type of regression used when the dependant variable is binary or ordinal (e.g. when the outcome is either “dead” or “alive”). It is commonly used for predicting the probability of occurrence of an event, based on several predictor variables that may either be numerical or categorical. For example, suppose a researcher

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Magical RUT with GIST

November 22, 2011
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Magical RUT with GIST

In search of better ways to post my R code, I finally discovered how GIST can help make my R blogging easier.  I know I am way behind, and I apologize to my loyal readers for my shortcomings.  Here is yesterday’s Magical Russell 2000 code u...

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Example 9.14: confidence intervals for logistic regression models

November 15, 2011
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Example 9.14: confidence intervals for logistic regression models

Recently a student asked about the difference between confint() and confint.default() functions, both available in the MASS library to calculate confidence intervals from logistic regression models. The following example demonstrates that they yield d...

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Logistic Power Peak (LPP) Simulated Soil Profiles

November 12, 2011
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Logistic Power Peak (LPP) Simulated Soil Profiles

A friend of mine recently published a very interesting article on the pedologic interpretation of asymetric peak functions fit to soil profile data (Myers et al., 2011). I won't bother summarizing or paraphrasing the article here, as the original artic...

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PostGIS Quickie

November 10, 2011
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Today I needed to cut out a rectangle of geologic data from a state-wide map in an AEA coordinate system, using a bounding box from a UTM zone 10 region, with the output saved in UTM zone 10 coordinates. PostGIS makes this type of operation very simple...

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Machine Learning Ex 5.2 – Regularized Logistic Regression

October 25, 2011
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Machine Learning Ex 5.2 – Regularized Logistic Regression

Now we move on to the second part of the Exercise 5.2, which requires to implement regularized logistic regression using Newton's Method. Plot the data:

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Machine Learning Ex4 – Logistic Regression

October 24, 2011
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Machine Learning Ex4 – Logistic Regression

Exercise 4 required implementing Logistic Regression using Newton's Method. The dataset in use is 80 students and their grades of 2 exams, 40 students were admitted to college and the other 40 students were not. We need to implement a binary classification model to estimates college admission based on the student's scores on...

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Visualizing GIS data with R and Open Street Map

October 8, 2011
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Visualizing GIS data with R and Open Street Map

In this post I way to share with you some code to use Openstreetmap – maps as a backdrop for a data visualization. We will use the RgoogleMaps-package for R. In the following I will show you how to make this graph. 1. Download the map I wanted to take a closer look at an

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StackExchange and CrossValidated: An Epidemiologist’s Review

September 20, 2011
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StackExchange and CrossValidated: An Epidemiologist’s Review

This seems like as good a day as any to review CrossValidated, and the whole StackExchange constellation of websites. It’s been a month since I joined, exactly, and today I also crossed the 1,000 reputation threshold on the site. So why not give my impressions of it? First, how I got there in the first

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