2602 search results for "gis"

Measuring persistence in a time series : Application of rolling window regression

Measuring persistence in a time series : Application of rolling window regression

During my final semester at IGIDR I did a project paper in macroeconomics involving timeseries econometrics. The concept that I focused on my study was unit root, which I have touched upon in my earlier posts. This study presents a novel...

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How to tell when error bars correspond to a significant p-value

July 24, 2012
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How to tell when error bars correspond to a significant p-value

Can you tell when error bars based on 95 % CIs or standard errors correspond to a significant p-value? Don’t fret if you think it’s hard, a study from 2005 showed that researchers in psychogoly, behavior neuroscience and medicine had a hard time judging when error bars from two independent groups signified a significant difference.

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get UCSC images for a list of regions in batch

July 24, 2012
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Here is my working R code for the task. It can be simplified as 3 lines.# example of controling individual track#theURL="http://genome.ucsc.edu/cgi-bin/hgTracks?db=mm9&wgRna=hide&cpgIslandExt=pack&ensGene=hide&mrna=hide&intronEst=hi...

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The Failure of Asset Allocation – Bonds Are An Imperfect Hedge

July 24, 2012
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The Failure of Asset Allocation – Bonds Are An Imperfect Hedge

US investors were spoiled by US Treasuries which acted as a near perfect hedge to stocks during the 2008-2009 crisis.  However, in real crisis, bonds rarely offer any comfort, and asset allocation fails (see post Death Spiral of a Country and IMF ...

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What’s wrong with LOESS for palaeo data?

July 24, 2012
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What’s wrong with LOESS for palaeo data?

Locally weighted scatterplot smoothing (LOWESS) or local regression (LOESS) is widely used to highlight “signal” in variables from stratigraphic sequences. It is a user-friendly way of fitting a local model that derives its form from the data themselves rather than having … Continue reading →

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What’s wrong with LOESS for palaeo data?

July 24, 2012
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What’s wrong with LOESS for palaeo data?

Locally weighted scatterplot smoothing (LOWESS) or local regression (LOESS) is widely used to highlight “signal” in variables from stratigraphic sequences. It is a user-friendly way of fitting a local model that derives its form from the data themselves rather than having to be specified a priori by the user. There are generally two things that a user has...

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Deploy Rook Apps with rApache: Part I

July 23, 2012
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Since rApache 1.1.15 you’ve been able to deploy you Rook applications like so: # Run the Rook application named 'app'. On each request, the expression # 'Rook::Server$call(app)' is evaluated in an environment populated by # rookapp.R. 'app' is expected to be found in that environment. <Location /test/RookApp> SetHandler r-handler ...

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Modeling Trick: Impact Coding of Categorical Variables with Many Levels

July 23, 2012
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Modeling Trick: Impact Coding of Categorical Variables with Many Levels

One of the shortcomings of regression (both linear and logistic) is that it doesn’t handle categorical variables with a very large number of possible values (for example, postal codes). You can get around this, of course, by going to another modeling technique, such as Naive Bayes; however, you lose some of the advantages of regression Related posts:

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Third year wrap-up

July 23, 2012
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Third year wrap-up

July marks the end of three years of blogging for us. By our count, we've posted 121 examples across the first three years. We aim to be helpful and interesting.As always, it's hard to get a sense of our readership. At the time we wrote this, Feedbur...

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London Olympics and a prediction for the 100m final

July 22, 2012
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London Olympics and a prediction for the 100m final

It is less than a week before the 2012 Olympic games will start in London. No surprise therefore that the papers are all over it, including a lot of data and statistis around the games. The Economist investigated the potential financial impact on spons...

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