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Category: Science

Awesome underwater maps of the Indian Ocean, thanks to MH 370

Geological Insights from Malaysia Airlines Flight MH370 Search

»The tragic disappearance of Malaysia Airlines flight MH370 on 8 March 2014 led to a deep-ocean search effort of unprecedented scale and detail. Between June 2014 and June 2016, geophysical survey teams aboard ships used echo sounding techniques to create state-of-the-art maps of the seafloor […] of the southeastern Indian Ocean.

[…] Previous ocean floor maps in this region had an average spatial resolution (pixel size) of more than 5 square kilometers, but the new maps resolve features smaller than 0.01 square kilometer (an area slightly larger than a soccer field).«

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The GRIM test and data in scientific papers

The GRIM test is very simple. The acronym stands for “granularity-related inconsistency of means (GRIM) test” – it evaluates whether reported averages can be made out of their reported sample sizes, and it works on integer data and small N.

Here is how this works:

Let’s make a pretend sample of twelve undergraduates, with ages as follows:

17,19,19,20,20,21,21,21,21,22,24,26

The average age is 20.92 (2dp), and we run the experiment on a Monday.

However, the youngest person in our sample is about to turn 18. At midnight, their age ticks over, […]

[W]e run the experiment again on Tuesday. Now our has the following age data:

18,19,19,20,20,21,21,21,21,22,24,26

The average age is 21 exactly.

Now, consider this: the sum of ages just changed by one unit, which is the smallest amount possible. It was 251 (which divided by 12 is 20.92), and with the birthday of the youngest member, became 252 (which divided by 12 is 21 exactly).

So if the mean cannot be the product of a division by 12, the data must be fake. The authors collected 260 phsychology papers and checked the reported stats to see if the results are even possible. Many are not.

 

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Lianas, Superhighways of the Canopy

The Atlantic reports research on the size of ant populations living in the treetops of forests in Panama. These treetops function as islands, if the tree in question has no vines connecting it to other trees nearby, with the size and diversity of the population being proportional to the tree size.

This changes as soon as the canopy is interconnected by lianas, which function as superhighways in the sky, connecting the various treetops into one single environment.

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Video: 20 Years of continuous improvement in crash safety

Continual improvement is sometimes hard to see, because each iteration, each incremental step itself is tiny so that the actual change escapes our attention.

Also, just living our lives, our time sense is sometimes distorted. Me for example, I was almost 30 already in the late Nineties, and while that is already 20 years ago, it feels like yesterday to me.

So car safety in the Nineties, compared to now? It was crap. Check this out:

We do learn, and things do get better. Change is not radical, most of the time it’s evolutionary. And to make it visible, you have to look really hard and contract now and then.

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The Best Democracy Money Can Buy (4)

Jean-Baptiste Quéru looks at US Manufacturing vs Trade in this Google plus article:

Here’s what I read in it, at a high level:

  • The US didn’t lose manufacturing to trade, since manufacturing went up after trade agreements were signed in 1994 and 2001.
  • US workers didn’t lose jobs to immigrants, since that would typically result in an increase in the workforce (more workers, paid less, individually less productive). Instead, the jobs truly disappeared.

He concludes that trade agreements increase trade, increase revenue, which is then invested into manufacturing automation, which leads to a drop in employment.

His analysis is based on data shown in this report from the American Enterprise Institute, a Washington based neoconservative think tank.

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