Dangers of forcing regressions through the origin

17 10 2017

correlationsI had an interesting ‘discussion’ on Twitter yesterday that convinced me the topic would make a useful post. The specific example has nothing whatsoever to do with conservation, but it serves as a valuable statistical lesson for all concerned about demonstrating adequate evidence before jumping to conclusions.

The data in question were used in a correlation between national gun ownership (guns per capita) and gun-related deaths and injuries (total deaths and injuries from guns per 100,000 people) (the third figure in the article). As you might intuitively expect, the author concluded that there was a positive correlation between gun-related deaths and injuries, and gun ownership:

image-20160307-30436-2rzo6k

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Now, if you’re an empirical skeptic like me, there was something fishy about that fitted trend line. So, I replotted the data (available here) using Plot Digitizer (if you haven’t yet discovered this wonderful tool for lifting data out of figures, you would be wise to get it now), and ran a little analysis of my own in R:

Rplot01

Just doing a little 2-parameter linear model (y ~ α + βx) in R on these log-log data (which means, it’s assumed to be a power relationship), shows that there’s no relationship at all — the intercept is 1.3565 (± 0.3814) in log space (i.e., 101.3565 = 22.72), and there’s no evidence for a non-zero slope (in fact, the estimated slope is negative at -0.1411, but it has no support). See R code here.

Now, the author pointed out what appears to be a rather intuitive requirement for this analysis — you should not have a positive number of gun-related deaths/injuries if there are no guns in the population; in other words, the relationship should be forced to go through the origin (xy = 0, 0). You can easily do this in R by using the lm function and setting the relationship to y ~ 0 + x; see code here). Read the rest of this entry »





Vote for the 2016 Environmental Arsehat of the Year

20 12 2016

arsehat_greenIn March 2016 I requested nominations for the Environmental Arsehat of the Year, and you happily complied by providing many excellent suggestions.

I now request that you vote on these nominations using the polling widget that follows a brief description of each nominee and why they’ve been suggested by the CB.com community. Once the votes are tallied, I’ll post the ‘winner’ (loser) in a new post in early 2017. Happy voting!

The nominations (in no particular order)

Read the rest of this entry »





Getting your conservation science to the right people

22 01 2016

argument-cartoon-yellingA perennial lament of nearly every conservation scientist — at least at some point (often later in one’s career) — is that the years of blood, sweat and tears spent to obtain those precious results count for nought in terms of improving real biodiversity conservation.

Conservation scientists often claim, especially in the first and last paragraphs of their papers and research proposals, that by collecting such-and-such data and doing such-and-such analyses they will transform how we manage landscapes and species to the overall betterment of biodiversity. Unfortunately, most of these claims are hollow (or just plain bullshit) because the results are either: (i) never read by people who actually make conservation decisions, (ii) not understood by them even if they read the work, or (iii) never implemented because they are too vague or too unrealistic to translate into a tangible, positive shift in policy.

A depressing state of being, I know.

This isn’t any sort of novel revelation, for we’ve been discussing the divide between policy makers and scientists for donkey’s years. Regardless, the whinges can be summarised succinctly: Read the rest of this entry »





Western Australia’s moronic shark cull

4 07 2014

another stupid politicianA major media release today coordinated by Jessica Meeuwig in Western Australia makes the (obvious) point that there’s no biological justification to cull sharks.

301 Australian and International Scientists experts have today provided their submission to the Western Australia Environmental Protection Authority (EPA), rejecting the scientific grounds for the proposed three-year drum-line programme.

Coordinating scientist, Professor Jessica Meeuwig from the University of Western Australia said:

“To have over 300 researchers, including some of the world’s top shark specialists and marine ecologists, all strongly agreeing that there is no scientific basis for the lethal drum-line programme, tells you how unjustified the government’s proposal is. If the EPA and the Federal Minister for the Environment are using science for decisions, the drum-line proposal should not be approved.”

The experts agree that the proposal presents no evidence that the lethal drum-line programme, as implemented, will improve ocean safety. It ignores evidence from other hook-based programs in Hawaii and Queensland that have been shown to be ineffective in reducing shark attacks on humans.

Dr. Christopher Neff from the University of Sydney stated:

“There is no evidence that drum lines reduce shark bites. The Western Australia EPA now faces a question of science versus politics with global implications because it is considering establishing a new international norm that would allow for the killing of protected white sharks.”

The drum lines are ineffective and indiscriminate, with 78% of the sharks captured not considered ‘threatening’ to humans. Yet, scientifically supported, non-lethal alternatives such as the South African ‘Shark Spotter’ and Brazil’s ‘Tag and Remove’ programmes are not adequately assessed as viable options for Western Australia. Read the rest of this entry »





Alliance of Leading Environmental Researchers and Thinkers

11 03 2014

ALERTIf you’ve been following this blog or my Twitter feed over the last few weeks, you’ve surely noticed a few references to A.L.E.R.T. – the Alliance of Leading Environmental Researchers and Thinkers. You might also have asked yourself, what exactly is ALERT, and is it something I should pay attention to?

Today’s post attempts to explain this new organisation, and hopefully convince you that the answer to the second question is ‘yes’.

Several months ago, a slightly cryptic e-mail from eminent conservation biologist, Bill Laurance, arrived in my inbox. It asked – what do you think of this logo (see associated image)? A few e-mails later and a couple of minor tweaks, and we ended up with what I thought was a pretty cool logo for this new ‘ALERT’ thing. It wasn’t until quite some time later that I finally understood what Bill was attempting to create.

Is ALERT a news aggregator, a blog, an advocacy group, a science-communication resource or a science-policy interface? Why, yes it is!

Read the rest of this entry »





Australia’s (latest) war on the environment

3 03 2014

monkYes, the signs were there, but they weren’t clandestine messages written in the stars or in the chaos of tea-leaf dregs. We saw this one coming, but Australians chose to ignore the warning signs and opt for the American political model of extremism, religiosity, plutocracy and science denial.

Enter the ‘Tea Party’ of Australia – the ‘new’ Coalition where reigning Rex perditor Prime Minister Tony The Monk Abbott1 has, in just a few short months, turned back the clock on Australian environmental protection some 40 years.

Yes, we saw it coming, but it wasn’t a tautological fait accompli just because it concerned a ‘conservative’ government. It’s difficult to remember, I know, that conservative governments of yesteryear implemented some strikingly powerful and effective environmental legislation. Indeed, it was the former incarnation of the Coalition government that implemented the once-formidable Environmental Protection and Biodiversity Conservation (EPBC) Act under the direction of then Environment Minister, Robert Hill. A colossus of sorts, the EPBC suffers from many ailments. While it’s the only really bitey environmental legislation we’ve got, that colossus is a lumbering, limping giant missing more than a few teeth – it needs a complete overhaul.

As most Australians are unfortunately aware, The Monk repeatedly and defiantly promised to repeal the Labor-government carbon price implemented in July 2012, despite the absolute necessity to tax the heaviest pollutersWhile somewhat sheepish about his recent climate disruption denialism following his election in 2013, a denialist he remains:

Let us re-familiarise ourselves with some of his historical pearlers: Read the rest of this entry »





Making science matter

14 10 2013
© XKCD

© XKCD

I’ve been home from my last overseas trip now for nearly two weeks, but despite not feeling caught up, it’s high time I report what I was up to.

Some of you who follow my Twitter feed or who saw a CB post about cartoonist Seppo Leinonen know that I was visiting the University of Helsinki to participate in a three-day short course for PhD students entitled ‘Making Science Matter‘. I was so impressed with how well Mar Cabeza and Tomas Roslin put together the course, that I thought I’d share the format with CB readers (just in case any of you out there can be convinced to design a similar course at your university).

I think it’s important first to discuss the philosophy of the course and what it hoped to provide those early-career researchers.

Most science PhD students will tell you once they’ve completed their degree that they feel completely unprepared to launch themselves into the extra-curricular world of communicating their science beyond the ‘traditional’ (peer-reviewed journals) outlets. Swamped with learning how to write concisely and clearly, getting up to speed with the entire body of theory on which their projects are based, mastering advanced modelling and statistical approaches and learning how to apply efficient computer code, it’s no wonder that many students find precious little time for anything else (including families, good food and proper hygiene).

Once they do land that precious post-doctoral fellowship though, they are immediately expected to interact professionally with the media, embrace social media and give fantastic public lectures to engage the uninformed. Right. Read the rest of this entry »