Nerd of this parish.
Jun 20
As of today, I will have spent precisely half of my life at $PLACE_OF_WORK. I first arrived at what would become my workplace as a badly coiffured youth in 1995 to do a biology degree. South Kensington seemed a great improvement over Croydon, where I had endured my previous 18 years: there was a refreshing absence of casual street violence, and a greatly …
Jun 04
![Flying machines [CC-BY-SA-3.0 Steve Cook]](https://www.polypompholyx.com/wp-content/uploads/2014/06/flying_machines-300x199.jpg)
It is frequently, and largely accurately, said that an area of Amazon rainforest the size of Wales is deforested every year. Horrendous though this statistic is, it’s worth remembering that the UK deforested an area at least the size of Wales (including most of the area commonly known as “Wales”) before anyone started keeping notes. The UK’s track record at maintaining its biodiversity has been – …
Apr 23
![Amsterdam botanical gardens [CC-BY-2.0 Alex Lomas]](https://www.polypompholyx.com/wp-content/uploads/2014/04/amsterdam_botanical_gardens-273x300.jpg)
I’m not sure whether bagging botanical gardens is better or worse than bagging Munros, Michelin stars or the numbers off of rolling stock, but it keeps me off the streets… London (Kew) Just ten stops down the District Line from $WORK lies the Royal Botanic Gardens Kew. The gardens have three enormous glasshouses, a number …
Mar 06
![Diadema setosum [CC-BY-SA-3.0 Steve Cook]](https://www.polypompholyx.com/wp-content/uploads/2014/02/Diadema_setosum-224x300.jpg)
It’s amazing how informative an anus can be. Take this sea urchin. The orange pucker in the middle of the spines is its “around-the-bum”, although zoologists would insist on writing that in Greek as “periproct“. The bright orange ring-piece is characteristic of this species, and marks it out as Diadema setosum, rather than any of …
Mar 03
![Species-area relationship for Caribbean herps [CC-BY-SA-3.0 Steve Cook]](https://www.polypompholyx.com/wp-content/uploads/2014/03/species_area_relationship_caribbean_herps-300x300.png)
Nonlinear regression is used to see whether one continuous variable is correlated with another continuous variable, but in a nonlinear way, i.e. when a set of x vs. y data you plan to collect do not form a straight line, but do fall on a curve that can be modelled in some sensible way by …
Feb 24
The technique for a one-way ANOVA can be extended to situations where there is more than one factor, or – indeed – where there are several factors with several levels each, which may have synergistic or antagonistic effects on each other. In the models we have seen so far (linear regression, one-way ANOVA) all we …
Feb 24
Analysis of variance is the technique to use when you might otherwise be considering a large number of pairwise F and t tests, i.e. where you want to know whether a factor with more than 2 levels is a useful predictor of a dependent variable. For example, cuckoo_eggs.csv contains data on the length of cuckoo eggs laid …
Feb 17
A χ2 test is used to measure the discrepancy between the observed and expected values of count data. The dependent data must – by definition – be count data. If there are independent variables, they must be categorical. The test statistic derived from the two data sets is called χ2, and it is defined as …
Feb 10
Linear regression is used to see whether one continuous variable is correlated with another continuous variable in a linear way, i.e. can the dependent variable y be modelled with a straight-line response to changes in the independent covariate x: Here b is the estimated slope of the best-fit line (a.k.a. gradient, often written m), a …
Feb 03
If you want a random yes/no answer to a question, like “who should kick-off this football match?” it’s very common to entrust the decision to the flip of a coin, on the assumption that the coin doesn’t care which side gets the advantage. But what if that trust is misplaced? What if the coin gives …