Category: Olden goldies

Spiders, sowbugs and sundew statistics

Statisticians often like to think that non-statisticians don’t know what exactly it is that we do. The truth is of course that not only do they not know, they do not particularly care! With the possible exception of someone like Nat ‘2012 US election’ Silver, what statisticians are thought to do is about as exciting as driving around in  cardigan and slippers in a two-tone ’74 Morris Marina with no radio.

But what  if statisticians went around ripping up floorboards and counting up spiders? Now you’re talking!!

Back in ’46 a scientist named LC Cole published some data on counts of spiders, and sowbugs, (or woodlice, roly poly’s or slaters).

Cole and various bright sparks ever since, had the idea of fitting the spider / sowbug counts to various types of probability distribution. Voila!, it was found that spider counts could be quite happily fitted by the Poisson distribution, as can the number of typewriter errors made on a page, the number of people killed by horse kicks in the Prussian cavalry, etc etc.

But not sowbug counts, which are better fitted by a ‘contagious distribution’, such as the ‘generalized Poisson’ or ‘generalized Negative binomial’, in which the event of something happening is itself dependent on other events. Sowbugs, it seems are a social breed, and when they notice their numbers dwindling, to the point where there’s only one or two left, they pick up sticks and try the house down the road, in search of other sowbugs, if not adventure.

Spiders, on the other hand, are more individualistic or anti-social and don’t care if they’re left by themselves.  (In fact they probably appreciate the peace and quiet after those pesky sowbugs have marched off elsewhere, unless of course the spiders belong to the  type known as woodlouse spiders or sowbug hunters, which is a very different kettle of fish, or spiders, altogether, as are ‘shy spiders’and ‘social spiders’)

Finally, a paper published in the journal of the highly prestigious Royal Society in 2010 found that carnivorous wolf spiders (Lycosidae) and pink sundew plants (Drosera capillaris) competed with each other for available food, in statistically interesting ways, indeed the lead author described the study as ‘awfully fun’ http://www.livescience.com/8566-plant-spider-compete-food.html
http://www.americanscientist.org/issues/pub/2010/6/in-the-news-30
http://ittakes30.wordpress.com/2010/10/25/feed-me-seymour/

So, next time someone asks (without really caring what the answer is) ‘just what is it that statisticians actually do.?….’.

[updated, 9 October 2016]

References

Cole LC (1946) A study of the cryptozoa of an Illinois woodland. Ecological Monographs, 16, 49-86.

Consul PC (1989) Generalized Poisson distributions. Marcel Dekker, New York.

Forbes C, Evans M et al (2011) Statistical distributions. 4th ed. Wiley, Hoboken, New Jersey.

Janardan KG et al. (1979). Biological applications of the Lagrangian Poisson distribution. BioScience, 29, 599-602.
Jennings DE et al. (2010). Evidence for competition between carnivorous plants and spiders. Proc Royal Society B, 277, 3001-3008.

Raja TA, Mir AH (2011). On applications of some probability distributions. Journal of Research & Development, 11, 107-116.

Watch the Skies: Manga Regression!

Although it’s probably the technique most employed by statisticians, regression or at least multiple linear or multiple logistic regression, is often the concept that is most feared or misunderstood by students and newbie researchers. If someone you know is in the latter categories, and they would like a fun and straightforward introduction to regression that literally uses pictures (cartoons), announce that The Manga Guide to Regression book has now been published, around May 2016,  by the friendly folks at NoStarchPress    http://www.nostarch.com/regression

and available  on http://www.oreilly.com   http://www.amazon.com   http://www.bookdepository.com   http://www.dymocks.com.au etc

Authored by Shin Takahashi (Manga Guide to Statistics, 2008), the new book uses Manga http://en.wikipedia.org/wiki/Manga   (think Osamu Tezuka’s Jungle Emperor: made into the 1965 Japanese anime TV series of the same name and the 1966  US overdub ‘Kimba the White Lion’  http://en.wikipedia.org/wiki/Jungle_Emperor, as well as ‘Atomu’ / Astro Boy’ .

Okay, Kimba himself is not actually included in the Manga Regression  book, but there’s both linear and logistic regression, demonstrated using Microsoft Excel (just a slight gritting of teeth, go for Excel 2010/2013/2016 or higher,  but at least it might allow getting ‘down and dirty with data’.

 

Telstar, Cortina & the Median Quartile Test: where were you in ’62?

It was 1962, the setting of the iconic 1973 movie American Graffiti, from which comes the subtitle of this post. The Beatles had released Love Me Do, their first single. That year also heard and saw Telstar, the eerie but joyful Claviolined Joe Meek instrumental by the Tornados, celebrating the circling communications private transatlantic television satellite it honoured. The British Ford Cortina, named after an Italian ski-resort saw out the humpty-dumpty rounded Prefects and 50’s Zephyrs, while in the US, the first of 50 beautiful, mysterious and largely lost Chrysler Ghia Turbine cars was driven in Detroit.

Meanwhile, the world of statistics was not to be outdone. Rainald Bauer’s Median Quartile test, an extension of Brown and Mood’s early 50’s Median Test, was published, in German, in 1962. The latter test, still available in statistics packages such as IBM SPSS, SAS and Stata simply compares groups on counts below and above the overall median, providing in the case of two groups, a two by two table.

The Median Quartile Test (MQT), as the name suggests, compares each group on the four quartiles.  But the MQT is largely unknown, mainly discussed in books and papers published in, or translated from, German.

The MQT conveys similar information to John Tukey’s boxplot, shows both analysts and their customers and colleagues where the data tend to fall, and provides a test of statistical significance to boot. Does one group show a preponderance of scores in the lower and upper quartiles for example, suggesting in the field of pharma fr’instance, that one group either gets much better or much worse.

A 1967 NASA English translation of the original 1962 Bauer paper is available in the Downloadables section of this site.

Recent Application in Journal of Cell Biology

Click to access 809.full.pdf

Further / Future reading

Bauer RK (1962) Der “Median-Quartile Test”… Metrika, 5, 1-16.

Von Eye A  et al (1996) The median quartiles test revisited. Studia Psychologica, 38, 79-84.

Olden goldies: Cybernetic forests 1967

Richard Brautigan was an American author and poet who, in 1967’s Summer of Love in San Francisco, published ‘All Watched Over by Machines of Loving Grace’, wishing for a future in which computers could save humans from drudgery, (such as performing statistical operations by hand?)

Apart from the perkier PDP ‘mini-computers’, computers of Brautigan’s day were hulking behemoths with more brawn than brain, and a scary dark side, as seen through HAL in 1968’s ‘2001: The Space Odyssey’.

Brautigan’s poem applied sweet 1960’s kandy-green hues to these cold & clanging monsters, just a few years away from friendly little Apple and other micro’s of the 70’s & 80’s. Now we are all linked on the web, and if we get tired of that we can talk to the electronic aide and confidante Siri, developed at Menlo Park, California – not too far away in space, if not time, from where Brautigan wrote.

We can get a glimpse of a ‘rosy’ future in the even friendlier electronic personality operating system of Spike Jonze’s new movie ‘Her’.

In his BBC documentaries of 2011, named after Brautigan’s poem, filmmaker Adam Curtis argues that computers have not liberated humanity much, if at all.

Yet there is still something about Richard Brautigan’s original 1967 poem, something still worth wishing for!

All three verses, further information and audio of Mr Brautigan reading his poem can be found at

http://www.brautigan.net/machines.html

CSIRAC, a real-life Australian digital dinosaur, that stomped the earth from 1949 to 1964, and is the only intact but dormant (hopefully!) first generation computer left anywhere in the world, can be viewed on the lower ground floor of the Melbourne Museum.

(and yes, this computer was used for statistical analyses, as well as other activities, such as composing electronic music)

http://museumvictoria.com.au/csirac/