Publications by mareviv
…about R, for beginners
These days I was remembering my beginnings as a linux user few years ago, and how I found R (possibly in a very unlikely way: searching for a SPSS alternative in Linux). For two years, R had been almost impossible for me. I didn’t understand its syntax (I don’t have programming background), and luckily I had installed R Commander (Rcmdr) to p...
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…start using Sweave, from scratch!
INTRODUCTION Sweave is nothing more, nothing less than the best way R can connect with a text editor, in this case LaTeX. So you don’t know anyting about LaTeX? neither did I 8 months ago… The hyperlinks in this post will take you to some great pages, to learn different things in an organised way. Here’s how I did it (with lots of help from...
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…learning LaTeX, from scratch!
” LaTeX is a high-quality typesetting system; it includes features designed for the production of technical and scientific documentation, and is the de facto standard for the communication and publication of scientific documents.” It is also… Free and Open. Specially designed for beautiful documents even when they include special language: ...
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… ridiculously photogenic factors (heatmap with p-values)
Some months ago, I had to explore a vast amount of categorical variables before making some multivariate analyses. One good way to know your raw data, to make new hypotheses…etc, is to calculate some pairwise “crude” chi-square tests of independence of your factors, but it can be very time-consuming. I mean, not time-consuming to make the t...
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heatmaps with p-values (2)… coloured according to odds ratio
I like heatplots with p-values -or frequencies, or whatever-. Not very conclusive, but pretty anyway. And when talking about graphs, pretty will make our neurons to fire in more interesting ways: neurons like “pretty” graphs. Moreover, observing your data can be as important as analysing it. It’s better to observe, to listen your patients t...
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Using gdata, for MS Windows users
I use both GNU-Linux and Windows systems on a regular basis… so I’m aware of the advantages (more for GNU-Linux in my case) and disadvantages of both. Recently I needed to analyse a database from a remote location, an Excel (*xlsx) file. The problem was that I couldn’t put my gdata library to work… some weird errors about a missing Perl i...
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Biostatisticians… beware of fuzzy researchers!
In the last days I was thinking about about how researchers could collaborate efficiently with their experts in statistics. With the increasing complexity in science, interchanging information can be crucial to get the best results. But what happens when a researcher doesn’t give all the information a statistician needs?. When someone asks for ...
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An .EPS to .PDF converter (using LaTeX!)
I am about to go on a short holiday, so I was tidying the code lines I had scattered around before leaving… And I found this: a minimal EPS to PDF converter, which is barely a LaTeX template. It is intended for transforming an .EPS graph to the .PDF format. You can copy & paste this whole code into a blank text file (but with .TEX extension) an...
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Power and sample size calculator for mitochondrial DNA association studies (Shiny)
The functions detailed inside the piece of code below (in a Gist) has been useful for me when I had to calculate many possible scenarios of statistical power and sample size. The formulae were taken from the article of Samuels et al., AJHG 2006, and the script showed even useful for making a variety of comparative plots. This is intended for esti...
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…start using R, from scratch!
Some time ago, since I was able to use R by myself, have found some fellows and other people who wanted to learn R as well. Then I pointed them to help pages, to CRAN repositories… but in some cases they said that didn’t know how to start using those resources. Obviously, the main self-perceived limitation for non-programmers is the use of �...
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