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First Time At Niche Modeling?

This is a blog on the power of numeracy. My first book — Niche Modeling — is now in print.

The first six chapters are tutorial topics in R programming and theoretical topics in niche modeling: functions, data, spatial, topology, environmental data collections, and examples. The last six chapters are about using niche modeling to detect errors: bias, autocorrelation, non-linearity, long term persistence, circularity and fraud - useful information for any biological modeler.

September 19, 2006

Examples of Eviews Code

Filed under: Uncategorized, Statistics, Finance — davids @ 4:34 pm

Eviews is one of the popular econometrics packages being used by research community and academicians. It is a GUI (Graphical User Interface) based program compatible with Windows and Macintosh operating systems. Other popular econometrics packages include, SHAZAM, LIMDEP, SAS and GAUSS etc. Eviews is one of the most popular software for analyzing time series data. Eviews, produced by Quantitative Micro Software (QMS) from Irvine, California, comes with very useful user guide and reference manuals called, The Users Guide and The Command and Programming Reference (www.eviews.com). If you are familiar with programs like C++ and Gauss you will be able to use your programming skills to run your own customized protocols in Eviews. Let us view some examples of Eviews code here. (more…)

September 11, 2006

Autocorrelation in GAM and GRASP

Filed under: Ecological Niche Models — davids @ 12:27 pm

Autocorrelation in GAM and GRASP models is an important topic of discussion since these models are being widely used in predictive animal and plant distribution models in the discipline of ecology.

The most widely used statistical models in the fields of ecological modeling, biodiversity and conservation are Generalized Linear Models (GLM) and GAM (General Additive Model) which is a semi-parametric extension of GLM. GRASP stands for Generalized Regression Analysis and Spatial Prediction (http://www.cscf.ch/grasp/grasp-s/welcome.html). GRASP is a combination of advanced S Plus functions and GIS (Geographical Information System) Many of these applications can be run through the software “R” (www.r-project.org).

What is Autocorrelation?

Autocorrelation describes correlation between a process, say Xt, at a different point of time Xs. The autocorrelation function can be depicted in a formula as

eqnautocor.PNG

where Xt has the variance σ2 and mean μ. E is the expected value. The result will range between -1 and 1. 1 indicates perfect correlation while -1 indicates perfect anti-correlation. You must note that the function should be well defined. (more…)

September 5, 2006

A Glossary of Content

Filed under: Uncategorized, Markets — admin @ 6:17 pm

Before launching into a controversial topic, it is a good idea to get the definition of terms straight, so I put together a glossary of forms of content found on the web. By no means complete, please feel free to add more. Content is a form of information, here referring mainly to text, or text and images together that form a coherent work, referred to as an article.

Free Content

Free content is work legally usable without paying a fee, although legal restrictions may exist on modification, redistribution, and attribution.

Open Content

Open content, generally free, may be redistributed provided it remains unaltered. Open content license also allows the charging of a fee for services but not for the OC material itself. The OC license also allows modification providing attribution information, OC license and zero cost remain intact.

Syndicated Content

Content syndication referees to the distribution of content to multiple Web sites through technologies as RSS, or catalogs of articles. The most common examples are the use of selective RSS newsfeeds to populate web pages with relevant daily changing updates.

Original Content

Original content refers to work that is significantly unlike any other work as to be regarded as ‘original’. For example, an original work would be expected to pass the plagiarism test at copyscape.com. Sources of original conent include vast compendiums such as ezine articles.

Custom Content

Custom content, in contrast to the above forms is paid for, and developed to the clients specifications. It should be original content, without the legal limitations of the above forms as it becomes owned by the client, and may be attributed to him/her, an used in any way. A familiar example of custom content is ‘advertising copy’ describing products for sale.

Creative Content

Creative cont