Blog Posts by Andrew B. Collier / @datawookie


Creating More Effective Graphs

A few years ago I ordered a copy of the 2005 edition of Creating More Effective Graphs by Naomi Robbins. Somewhat shamefully I admit that the book got buried beneath a deluge of papers and other books and never received the attention it was due. Having recently discovered the R Graph Catalog, which implements many of the plots from the book using ggplot2, I had to dig it out and give it some serious attention.

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Standard Bank: Striving for Mediocrity

Recently I was in my local Standard Bank branch. After finally reaching the front of the queue and being helped by a reasonably courteous young man, I was asked if I would mind filling out a survey. Sure. No problem. I had been in the bank for 30 minutes, I could probably afford another 30 seconds.

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Plotting Flows with {riverplot}

I have been looking for an intuitive way to plot flows or connections between states in a process. An obvious choice is a Sankey Plot, but I could not find a satisfactory implementation in R… until I read the post by January Weiner. His {riverplot} package does precisely what I am need.

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Comrades Marathon: A Race for Geriatrics?

It has been suggested that the average Comrades Marathon runner is gradually getting older. As an “average runner” myself, I will not deny that I am personally getting older. But, what I really mean is that the average age of all runners taking part in this great event is gradually increasing. This is not just an idle hypothesis: it is supported by the data. If you’re interested in the technical details of the analysis, these are included at the end, otherwise read on for the results.

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Where to Put EAs and Indicators in New MT4 Builds

If you are creating an EA or indicator from scratch, then the MetaTrader editor places the files in the correct location and the terminal is automatically able to find them. However, if the files originate from a third party then you will need to know where to insert them so that they show up in the terminal. For older builds of MetaTrader 4 the directory structure was fairly simple.

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Twins, Tripods and Phantoms at the Comrades Marathon

Having picked up a viral infection days before this year’s Comrades Marathon, on 1 June I was left with time on my hands and somewhat desperate for any distraction. So I spent some time looking at my archive of Comrades data and considering some new questions. For example, what are the chances of two runners passing through halfway and the finish line at exactly the same time? How likely is it that three runners achieve the same feat?

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Concatenating a list of data frames

It’s something that I do surprisingly often: concatenating a list of data frames into a single (possibly quite enormous) data frame. Until now my naive solution worked pretty well. However, today I needed to deal with a list of over 6 million elements. The result was hours of page thrashing before my R session finally surrendered. I suppose I should be happy that my hard disk survived.

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Comrades Marathon Pacing Chart: Down Run

Although I have been thinking vaguely about my Plan A goal of a Bill Rowan medal at the Comrades Marathon this year, I have not really put a rigorous pacing plan in place. I know from previous experience that I am likely to be quite a bit slower towards the end of the race. I also know that I am going to lose a few minutes at the start. So how fast does this mean I need to run in order to get from Pietermaritzburg to Durban in under 9 hours? Read More →

Race Statistics for Comrades Novices: Corrigendum

There was some significant bias in the histogram from my previous post: the data from all years were lumped together. This is important because as of 2003 (when the Vic Clapham medal was introduced) the final cutoff for the Comrades Marathon was extended from 11:00 to 12:00. In 2000 they also applied an extended cutoff.

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Comrades Marathon: Negative Splits and Cheating

With this year’s Comrades Marathon just less than a month away, I was reminded of a story from earlier in the year. Mark Dowdeswell, a statistician at Wits University, found evidence of cheating by some middle and back of the pack Comrades runners. He identified a group of 20 athletes who had suspicious negative splits: they ran much faster in the second half of the race. There was one runner in particular whose splits were just too good to be true. When the story was publicised, this particular runner claimed that it was a conspiracy.

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