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Things 2026 Q2: Fisherian runaway, Androids, effortful music videos

Quotes

Here’s some nice quotes that all draw out aspects of the Dunning-Kruger bias:

Idealism increases in direct proportion to one’s distance from the problem

– John Galsworthy

Ignorance more frequently begets confidence than does knowledge

– Charles Darwin

Everything looks simple when you don’t know the first thing about it

– Kevin Williamson

Having established that, I now return to confidently holding forth on things I’m not an expert in, probably annoying Darwin in particular. I leave you to judge how sensible that is.

Super-normal stimuli and Fisherian runaway

Bear with me on this one as I invoke the principles of sexual selection to explain burgers that are too tall to bite.

Part 1: Gestalt Perception

Perception usually feels effortless, but the process that makes it work is strange and subtle. Dozens of contextual clues (sight/sound/smell, movement/light/texture, size/silhouette/colour, and many more) are all subconsciously processed, usually based on previously observed patterns, and our conscious attention is directed to whatever that process deems the most salient aspect. For example, you might see a poster you’ve never seen before, but it has a picture of an actor you know, some words in an elaborate font, a release date and some small print, and without effort you recognise it as a film poster, as well as a good guess for the genre and if it’s likely to be worth paying more attention to.

The way many parts contribute subconsciously to our overall perception is summed up by the slang term ‘vibes’, but over the decades other terms have approximated this idea – ‘vibrations’ of course, but also in different contexts bag, energy, flavour, and more recently aura or “x-coded” (for something with various signifiers of x). Similarly people say an idea ‘doesn’t pass the sniff test’, not because they can smell abstract concepts, but because of how it comes across in almost every other way.

Part 2: Supernormal stimulus

Certain aspects of perception have clear dimensions to them. Most obviously things like bigger/taller/longer but also brighter/more-textured/more-saturated, and beyond. If we recognise an object based on it being notable in some dimension, an object with a stronger version of that attribute can register more quickly and more strongly as a signifier of that object. Further, I think that obviousness biases us to rate it as a ‘better’ example of that object in some way. If it has an unnaturally pronounced example of that attribute it can become a supernormal stimulus.

Wikipedia gathers some examples from the natural world here, for example:

  • Birds will nurture fake eggs over their own if they are larger or more saturated (and Cuckoos exploit this fact)
  • Butterflies that select mates by bright colour markings will prefer orange paper model butterflies over receptive real mates
  • Herring gull chicks seeking a parental beak for food will choose a red stick with yellow markings over a faithfully reproduced yellow-beak-with-red-dot replica gull head

Of course, we can intuitively understand this without tricking small animals in laboratory settings, because we are animals ourselves. For example, a drawing of a woman with a dramatically high hip/waist ratio or a man with an implausibly pronounced shoulder/waist ratio will read as stronger and more obvious examples of each sex, even if those ratios go beyond what nature would naturally produce. Some examples:

Designs from Disney’s Hercules (1997) – exaggerated but legible:

Designs from The Book of Life (2014) – frighteningly extreme, still works:

Beyond human secondary sexual characteristics, we can experience it in pretty much everything. A giraffe with an extra long neck is extra giraffe-ey; a stretched limo is an even greater affluence signifier than a regular limo; a monster with an excessive number of impractically long and excessively sharp teeth is extra monstery.

Part 3: Fisherian runaway / Sensory Exploitation Hypothesis

Natural Selection just by itself is an incredibly powerful theory, but some things defy it – a classic example being peacock’s wildly impractical tails. Less often remembered is that Darwin also theorised about Sexual Selection: genes that produce traits that elicit sexual preference will have a reproductive advantage, even if they have no survival advantage. But this on its own doesn’t explain the peacock.

Fisher’s suggestion was that the earliest version of the ‘ornament’ (the surprising feature the species developed) initially signalled greater potential fitness in the natural-selection sense, which meant a preference for that ornament also had an advantage. If the ornament and the preference are correlated (I assume mainly because genes for both get passed on together) you can enter a feedback loop of ever-more exaggerated ornaments that are just barely constrained by natural selection.

The ‘sensory exploitation hypothesis’ proposes that preference for exaggerated traits arises from sensory biases such as the supernormal stimuli I mentioned above. It seems pretty intuitive to me that this will help drive the Fisherian runaway effect far beyond what natural selection would usually tolerate. It’s a bit like Goodhart’s law – when a measure becomes a target, it ceases to be a good measure.

So a male peacock with an even bigger, brighter, more saturated and more ornamented tail will look even more appealing to a female peacock, and both the tail and the appreciation for the tail get passed on. Thus the tail becomes ever more extreme, until it finally bumps against natural selection’s hard limits.

No points are awarded for this, but I did come up with the sensory exploitation hypothesis myself! Only after looking for research did I learn that all the above is well-established, and that point about ornament and preference being correlated is the deeper insight.

Part 4: Fisherian runaway in capitalism

I do think this same process applies to capitalism:

  • Consumers select products by their utility. Products with greater utility are more selected, more successful, and so are produced more. Natural selection at work. A Drosselmeyer nutcracker is incredibly good at cracking nuts, so it does well in objective comparisons, and people like me will recommend it to anyone that wants to crack nuts.
  • In many cases the consumer can’t perfectly assess the utility of the product before purchase, so they rely on other signals. This becomes more like sexual selection.
  • We can fall victim to a super-normal stimulus here – a thing that depicts outrageously exaggerated traits looks more appealing, even if it’s beyond all reason. A 13-in-1 tool must be better than a 3-in-1 tool. Drinking Tango gets you slapped by an orange man. This car looks so good, fireflies follow it. These two people love this product, and they are very attractive!
  • Then the Fisherian runaway can start – to compete, those products need to show the super-normal stimulus, and then the only way to stand out is to exaggerate it even further until you eventually run aground on actual utility / natural selection.

Perhaps you think I’m mad, but remember the burgers?

As a food, a burger is notable for being quite tall – it’s a stack of three (or more) things. A burger can also seem more appealing if it has more than just a plain burger inside. So what happens? Burgers that are taller and have more additional things inside look like even better burgers. Before you know it, restaurants are serving burgers that have to be held together with a skewer and cannot even fit in a conventional human mouth. It’s like eating a peacock’s tail. Metaphorically.

(I’m not sure about the correlation element… perhaps it comes in when chefs eat a taller burger at some other restaurant and conclude they should make their own burgers even taller?)

What about cars? Some people feel safer or more masculine if their car is bigger than others. In America where petrol is relatively cheap (so the natural selection pressure of miles-per-gallon is lower), this effect has reached peacock tail levels of madness as cars become ever larger. The correlation kind-of happens here because obtaining a bigger car means other people, whose cars seemed sufficiently big before, now see a need to get even bigger ones.

Thanks to Instagram and similar social media, we get a similar effect for a bunch of things:

  • Treats/drinks that look amazing go viral and drive more sales (and more social posts, driving the correlation) than those that actually taste good
  • Holiday destinations that make for good photo opportunities start to do better than those that are actually enjoyable
  • Getting more abstract: a video/post that has a very high number of views seems like it must be more worthy of our attention
  • Bit of a stretch: a famous person having an opinion seems more compelling than an expert in that domain’s opinion

So as always… watch out for that.

Podcast – The Magnus Archives

The Magnus Archives is a supernatural horror fiction podcast that ran for 200 episodes across 5 seasons from 2016 to 2021.

I got into it essentially by the strength of the writing: I was at a craft fair and found a range of stickers with intriguing phrases like “The sky ate him” and “The world is always ending”.

Unfortunately I didn’t note the artist and the work is not signed!

The framing premise is that the eponymous Magnus Archives takes statements from anyone that has experienced something supernatural, and the Head Archivist is recording these statements out loud to tape in order to log them. In this way it takes a classic “spook of the week” form.

I liked that a lot of the elements of the premise that don’t really make sense end up being narratively justified – with the exception of the very non-diegetic spooky music, which was still excellent (especially the “and then things got really spooky” musical cue in season 1).

The spook-of-the-week setup has two tightropes the author must walk, which author Jonathan Sims talks about explicitly in some of the Q&A episodes: the balance between the weekly spook and a greater narrative, and the balance between raising questions and and answering them. For me, neither one is walked perfectly throughout – but Sims (who is also the lead voice actor) does a much better job of both than I’ve seen before. Even though for me the series peaked around 75% of the way through, I still strongly recommend it if you like spooky business.

Some points to note before jumping in:

  • Episode 1 (styled MAG 1) did not do much for me, MAG 2 is a better bellwether for what the rest is like, so I recommend sampling at least up to that point
  • There is a dedicated subreddit, with a thread for each episode featuring discussion by fans and no spoilers about future content. This can be quite fun for a debrief and help spotting deeper connections between things. (Hub of most of these threads can be found here)
  • There is a dedicated wiki with plot summaries and full episode transcripts, but you need to be very careful because immediately after the plot summary you will see information that spoils future episodes
  • My very favourite bit begins with the word “Hello”. You’ll know it when you get there
  • My least favourite bit is recurring characters that are constantly angry and obstinate
  • Probably avoid if you’re averse to the “endless suffering” trope
  • There’s a follow-up called “The Magnus Protocol” which is still running and I have not yet sampled

The home page with various links is here, but it’s probably easiest to just search ‘magnus archives’ in the podcast service of your choice.

The Androids are Coming

Because I’ve been writing Things for almost 20 years, I can see how some of my posts serve as a marker of developing technology, or at least my awareness of it. For example, I posted in 2015 this Google Research post about neural networks generating images, which is I think the precursor to generative AI art as we now know it.

Back in 2009 I posted about Boston Dynamics’ ‘Big Dog’. Developments in robotics carried on, with bipedal models eventually roaming free of connecting cables and getting increasingly human-shaped. They now seem to be at something of a turning point.

Compare the performance of China’s androids in the 2025 new year show here:

… with the 2026 new year show:

My guess was that android promotional material would shy away from any implication of violence to avoid reminding people of films like Terminator. I hadn’t accounted for the fact that state propaganda might actively want to promote martial prowess, hence the above. At least we can look at what’s coming directly instead of guessing.

Terminator style threats to humanity are a natural fear but I suspect are a low-probability / high-impact event (perhaps more likely in the form of perfectly efficient and numerous state police facilitating a concentration of power into an ever smaller number of human hands, rather than a bona fide machine uprising). Warfare is also a sufficiently incentivised area that bespoke robots (rather than androids) are arising already, starting with drones.

We’ve spent centuries building specific machines to tackle specific tasks efficiently. Building an android to do similar things seems laughably inefficient – a sledgehammer to crack a nut, or supercomputer to play tic-tac-toe. But there is of course a massive efficiency: we have tools, workplaces and entire paradigms built around the human form-factor. Making an android to solve one physical task is inefficient; making one that can do any human task imaginable, with more accuracy / strength / reliability than a trained human, is incredibly efficient.

In December 2024, Citigroup published this forecast of robot numbers by type. Humanoid robots (which I’m referring to as androids) are the most notable leap, getting a foothold in 2030 before exploding by 20250:

The leaps forward in AI, most notably visual processing, seem to have unlocked a major piece in this puzzle and make the above look more plausible to me. Here’s a couple more cases (like the Chinese New Year’s Show example above) that show the improvements in these models over recent years, and so gives an idea of the trajectory.

February 2025: Helix androids putting away shopping very slowly:

May 2026: Helix’s Figure 03 working a production line (and other things):

In a very direct test of a specific skill, there are contests in China in long-distance running for androids. In April 2025, one robot completed the half-marathon in 2 hours 40 minutes.

One year later, a robot completed the half-marathon in just over 50 minutes, beating the human record of 57 minutes (which immediately seems like a less relevant comparison).

I don’t expect this to be quick, so the slow initial commercial growth in the Citi forecast does look reasonable to me. I’m certain there will be massive bumps in the road as public perception and legal / insurance systems navigate around the inevitable accidents and abuses this technology will produce. But I now feel pretty confident that sci-fi visions of robot drivers, plant-pickers, and assistants are not at all fanciful.

I’ve also been reading a lot about what people think will happen to the humans whose jobs have been replaced. To distil everything, the answer is that… the result will be a product of huge numbers of competing systems and feedback loops, and as such is impossible to predict. It’s a bit like this Financial Times prediction of GDP based on different AI scenarios, which is quite funny and frightening at the same time:

Music videos where effort is the trick

This Things is getting a bit heavy, so let’s look at some Music videos in which a beautiful visual effect is achieved, but the amount of effort that must have gone into it is tremendous.

Director: Michel Gondry
Artist: Kylie Minogue
Song: Come Into My World

Once again Gondry finds a way to visualise the repetition of the song in a video that just keeps getting more impressive:

How did he do it? Well, he explains it and the inspiration here

His explanation seems to take for granted an enormous amount of compositing work, all the more impressive given that this was in 2002 when computer-assisted tools were less well developed. That said, it’s Gondry – possibly he found an incredibly efficient way to do this that he’s not revealing here. Or he just takes that “enormous effort” part for granted because he does that regularly.

Director: Nick Goffey and Dominic Hawley
Artist: The Chemical Brothers (with vocals by Beck)
Song: Wide Open
Dancer: Sonoya Mizuno
Effects: The Mill

Starting with a close-up to assure you that you’re looking at a real human dancer, something impossible starts to happen. Make sure to stick around until 3:28 (or just skip there if you’re busy) in which the video casually does something even more impressive.

How did they do it? Surely to do that you would need some sort of motion-controlled camera or real-time movement tracking, re-render almost everything in CG and then carefully composite the live-action with the CG with pinpoint precision?! The answer is yes, that’s exactly what they did:

Director: Páraic Mc Gloughlin
Artist: Weval
Song: Someday

If you take carefully framed photos of everyday objects and architecture with repeating patterns and show them in sequence, you get a strange sort of stop-motion effect. I saw this trick first used in Michael Langan’s 3-minute video Dahlia (2008), then in Thomas Sauvin’s Recycled (2013) (seemingly no longer viewable but described here; a short snippet can be seen from 1’12” in this film festival trailer).  Páraic Mc Gloughlin pushes that idea even further with incredible smoothness, range and synaesthetic effect for Weval’s Someday (2019) music video (after about 21 seconds of build-up):

If you enjoyed that you could also try the video for IMANU – A Taste of Hope (Hallowvale) by Chris Takács and Kevin Rogerson; or enjoy spacelike slicing instead of timelike with the video for Max Cooper – Repetition by Kevin McGloughlin.

The AI Shovelware is here

Also in the category of marking developing technology, last time I wrote about the AI ‘trough of disillusionment’ referencing Mike Judge’s “Where’s the shovelware” article.

Well, true to how the Gartner hype cycle (sometimes) pans out, it turns out we were coming out of that trough.

The financial times looked back into those same trends (paywalled link) in February 2026 and found recent upticks in websites, iOS apps and GitHub repositories:

In April 2026, Naavik did a detailed overview of the topic just for games, showing not much effect on PC (although a rise in AI-discosed games), but a huge effect on mobile (especially on Android), showing the number of publishers is up, and the relative proportions of success have remained about the same.

That last point is particularly interesting because the feeling in games is that there are already way more games than the market can sustain (so the vast majority do essentially no business), so an AI-driven surge in new games could just dilute success and make it even harder for anyone to succeed at making games. The counter-argument would be that with a wider range of games, more niches are filled, so more people buy more games – for example, maybe I buy 6 games a year, but if there were twice as many that were twice as appealing to me maybe I would buy 9. If, as Naavik found, the relative proportions of success are about the same then these two effects perhaps cancel out. Or realistically, there’s lots of other effects and that data isn’t sensitive enough to detect them or their true net effect, and also not enough time has elapsed to feel the effects, so let’s just wait and see.

Still this does put more pressure on the question of ‘discovery’ – I can’t buy those amazing games if I don’t know they exist. Most people who work in video games seem to want discovery to get solved through some clever platform design, but I don’t think that’s very likely:

  • If I knew what I wanted and could find games that meet exactly that, just maybe we could solve it, but people do not know what they want! I would never have searched for something like Outer Wilds or Portal – in fact if I had searched for either of those accurately it would have effectively spoiled the game – but they were exactly what I wanted.
  • This type of problem is approximately solved in social media, where algorithms can serve content people are likely to enjoy (well enough that they keep scrolling, anyway) – but I don’t think people play enough games for you to run the kind of predictive models that work there
  • It might just about work if you took as input everything about you (social media consumption, books read, films watched etc on top of games played), but nobody holds all that data (yet)… and we feel uncomfortable with anyone holding all that data.

So in the absence of all that, we just get marketing.

Or some sort of procedural AI-generated game starts out as what you thought you wanted and evolves into what you actually needed based on your real-time reactions. That sounds a lot like a dream, or perhaps a nightmare, both figuratively and literally.

Perhaps more likely, in the future maybe your household android tracks all of that contextual data about you locally, and can then make perfect recommendations?

  • Transmission ends, stretching for a note of optimism

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Things August 2015: Movies, books and stand-up comedy

Momo (1973 novel)

Six years before The Neverending Story, Michael Ende wrote Momo, well known in his native Germany but undeservedly less well known here. It takes a fairly common message (to do with how you should spend your time / what is important in life), but rather than using a fantasy setting to metaphorically imply the message, he uses a fantasy setting as a way to state the message as directly and clearly as possible. Some books change how you look at life if you take the time to really think about them; Momo leaves you no choice. I thought it was brilliant.

Also, here’s a a quote from it that I like:

He looked down at the tortoise. ‘Cassiopeia, my dear, I’d like your opinion on something. What’s the best thing to do when you’re under siege?’

‘HAVE BREAKFAST,’ came the reply.

‘Quite so,’ said the professor

Street Fighter (1994 film)

The Street Fighter movie is fascinating. Here’s a few key facts that let you know right away something weird is happening:

  • Written and directed by Steven de Souza (the writer on Die Hard, The Running Man, among others)
  • Budget $35m ($57m in 2015 adjusted for inflation)
  • IMDb rating 3.7
  • Rotten Tomatoes rating 12%
  • Worldwide gross $99m ($161m in 2015 adjusted for inflation)

If nothing else, I highly recommend reading the Polygon article Street Fighter: The Movie – What Went Wrong, which pieces together the extraordinary story of how that movie came about. It sounds as if de Souza had a truly nightmarish experience as director, blocked from making the movie he wanted to at just about every turn (seriously – it’s incredible the movie got finished at all).

Having read the article I just had to see the movie for myself. As it turns out, it’s a rather brilliant B-movie that knows exactly how silly it is, and is tremendously enjoyable as a result! This often seems to be the case when the IMDb rating dips below 4.0 (it’s the 4.0-6.5 region you should avoid). My personal highlight: Guile (Van Damme), leading an assault on the bad guy’s base, in his state-of-the-art stealth speedboat, takes a moment to watch some home movie footage of himself and his good buddy (now captured) on a VHS casette he evidently brought with him, on the CRT monitor built into the stealth-speed-boat control panel, perhaps to remind himself what he’s fighting for. Amazing.

Even more brilliantly, there’s a director’s commentary evidently recorded by de Souza a few weeks after the movie came out (intended for the Laserdisc edition), in which he betrays no bitterness about the process of getting the film made, but rather conveys a genuine warmth for the material and pride in what they managed to achieve. The Street Fighter movie is a great example of someone being given life-lemons and making life-lemonade out of them.

Mitch Hedberg

I originally referenced Mitch Hedberg back in Things 104 in 2011. I finally bought one of his CD’s, Strategic Grill Locations, which is as funny as the many YouTube clips you can find of him would suggest, but instead lasts for almost an hour, which is pretty great.

He has some nice one-liners, such as:

I haven’t slept for ten days, because that would be too long.

But what I didn’t adequately convey in Things 104 is his delivery style. His laid-back demeanor and accent are part of it, but his unusual prosody is what really makes his material work. So I can give you this quote, which is okay, but it’s infinitely better when he’s saying it:

I was at the airport a while back and some guy said “Hey man, I saw you on TV last night.” But he did not say whether or not he thought I was good, he was just confirming that he saw me on television. So I turned my head away for about a minute, and looked back at him and said “Dude! I saw you at the airport… About a minute ago… And you were good.”

Stewart Lee

In some ways the mirror opposite of Mitch Hedberg and his non-sequitur one-liners, Stewart Lee makes long-form stand-up comedy. I didn’t really understand what he was trying to do until I read his book, which I guess makes him hard to recommend.

That said, when I saw him live, I found one particular segment – in which he responds to a silly statement from UKIP with a 12-minute long reductio ad absurdum argument – to be a brilliant result of the weird territory he has been exploring. So I was glad to find that someone has taken that segment from his TV series and put it online. (Link died, try this one or this Youtube search – T.M. 24/01/18)

(Weirdly this bit has now been abstracted into a song performed by Stewart Lee and Asian Dub Foundation – T.M. 17/5/22)

Zathura (2005 film)

Let’s have another breakdown:

  • Written by David Koepp (Jurassic Park, Mission Impossible, Indiana Jones… 4) and directed by Jon Favreau (Iron Man, Cowboys and Aliens)
  • Budget $65m
  • IMDb rating 6.1
  • Rotten Tomatoes rating 75%
  • Worldwide gross $64m

… ouch. So what went wrong there?

One problem was the release timing: they went out against Disney’s Chicken Little (which people went to in droves, assuming Disney’s first foray into 3D would be as good as Pixar – Chicken Little made more money than Disney’s Lilo & Stitch, conclusively disproving money as a measure of movie merit), and in the second week when people realised Chicken Little wasn’t that good, Harry Potter and the Goblet of Fire came out.

The other problem was the perception that Zathura was just “Jumanji in space, without Robin Williams”… which is actually a very accurate description.

But while it is that, it’s also brilliant, partly because space is cooler than jungle, and partly because Robin Williams isn’t the best thing about Jumanji anyway. Jon Favreau makes use of practical effects wherever possible (for example in the trailer below, that robot smashing through the doorway is literally doing that; even the jet-flames on the ships are practical), and this is particularly effective for the ever-increasing destruction of the house. Also featuring before-they-were-famous starring roles for Josh Hutcherson and Kristen Stewart, it’s just a really lovely film that is unjustly overshadowed by its precursor.

Okay, one caveat: there’s some stuff that’s almost cool sci-fi but then is instead just fantasy, which some of you might find a bit disappointing. As is so often the case, keep in mind it’s a fantasy film rather than a sci-fi one, and it’s all good.

– Transmission ends

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Things 112: Eyes, Guessing Cat, Amigara Fault

This week Things has a very slight Hallowe’en theme.

Puzzle
This is one where you should gather some people around the monitor and see who can do best: guess the cartoon (or CG) character from their eyes (mouse over the eyes to see the character outline that should tell you if you’re right).

And yes, it is pretty difficult – I only got 6, and I watch a lot of animation!

Video
Here’s a video that begs the question: is the cat playing the game, or just acting out of blind instinct?

http://www.youtube.com/watch?v=QrlTijuhVOA

To which the answer is to have a big argument about the definitions being used before concluding that you can’t tell.

Quote
In the wonderfully stylised animation The Secret of Kells, I heard the line “One beetle recognises another” and wondered if it was some kind of proverb. It turns out that it is, and actually – obviously – there are a whole bunch of Irish Proverbs, which in translated form become alternately profound, banal or hilarious, just as I imagine English proverbs must seem if you haven’t grown up with them. Here’s a list of them on Wikiquote, and here are a few of my favourites, for unstated reasons:

“Every beginning is weak.”

“Time is a good story teller.”

“A lamb becomes a sheep with distance…”

“The quiet are guilty”

Comic
The Enigma of Amigara Fault is a horror comic that impressed me with its unconventional approach. It’s 32 pages, and originally in Japanese so you have to read the panels right to left. But if you want a comic that will freak you out for Hallowe’en, it’s worth it. Unless you’re particularly claustrophobic, in which case you should probably steer clear of it entirely.

Answer – Malady X
In Things 111 I asked what the probability of having Malady X is if a randomly administered 99%-accurate test for it comes back positive. As Phil and Thomas noted, you can’t actually answer from this information alone: you also have to know what the probability of a random person actually having Malady X is. A lot of people don’t have an intuition for this fact. I’m going to attempt to explain ways to apprehend that hand-wavingly, mathematically, and visually.

Argument from hand waving and examples:
Imagine the probability of having Malady X is 0% – nobody has it. In this case, it’s certain that getting a positive result means you were simply in the 1% of cases where the test comes back incorrect.
Conversely if the probability of having it is 100% – everybody has it – then you must be in the 99% of cases where it is accurate. In this way, it’s clear the underlying probability influences the chances that the test is correct!

We might worry that these extremes somehow break the puzzle, so let’s imagine less extreme alternatives. Imagine 1,000 people are tested. If 50% (500) really have Malady X, on average we expect the test to come back positive for 99% of them (495) and also for 1% of the 500 that don’t have it (5). In this situation, 495 out of the 500 people for whom the test was positive actually have the disease – 99%.

Alternatively, if 1 person (or 0.1%) out of the 1,000 has the disease, they’re very likely to be correctly diagnosed, and we expect roughly 10 of the other 999 to get a positive result. In this case 1 out of 11 people with a positive result actually have Malady X – fewer than 10%. So clearly the underlying incidence level matters.

Argument from maths:
There are two probabilities at work: the chance the test is correct (99%) and the chance of anyone having Malady X (unknown – let’s call it X%). When you combine probabilities you multiply them, so for example the chance of anyone actually having Malady X AND getting a postive result is 99% times X%.

If someone gets a positive result and that’s all we know, we reason as follows:
A = Probability someone has Malady X and tests positive = X% times 99% times
B = Probability someone does not have Malady X but still tests positive = (100% – X%) times 1%
If you test positive, the chance you actually have it is C = A / (A+B). But if you haven’t studied probability carefully, I’m not sure you could infer this, which is why I like to come up with other ways of getting a feel for the correct answer.

Argument from visualisation:
Since there are two probabilities in question, and we combine probabilities by multiplying, this naturally suggests a visualisation where probability is represented by rectangular area (since area is calculated by multiplying height by breadth).

For example, if we imagine the actual incidence rate of Malady X is 50%, the picture would look like this (click for big):

If the test result is positive, you either have it and the result is correct (big yellow area) or you don’t have it but the test was incorrect (small dark blue area). The chance of you actually having Malady X is equal to the proportion of those combined areas that is yellow. In this case:
Yellow = 99% x 50% = 49.5%
Dark blue = 1% * 50% = 0.5%
Probability you have it = Proportion that is yellow = 49.5% / (49.5% + 0.5%) = 99%.

Alternatively if the incidence rate is, say, 2%, it looks like this:

Here we see the yellow and dark blue areas are very similar, so the chance of you being one or the other is much more even. In fact, it’s:
Yellow = 99% x 2% = 1.98%
Dark blue = 1% x 98% = 0.98%
Probability you have it = Proportion that is yellow = 1.98% / (1.98% + 0.98%) = 67% (ish).

As Peter Donnelly shows in this TED talk, this actually has some severe ramifications, because when the probability of the thing being tested for is extremely low, it becomes overwhelmingly likely that a positive result is false, but people intuitively feel that a 99% accurate test should be correct 99% of the time.

Thomas also noted:

If anyone is interested in playing around with the probabilities (even if you’re not familiar with the maths), I recommend GeNIe:
http://genie.sis.pitt.edu/
It lets you create networks of dependencies, set evidence and work out probabilities in problems just like these.

-Transmission finally ends

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Things 53: Sita Sings the Blues, FFFFound Quotes

(Originally sent July 2009)

A slightly different format for Things this week, as I have two things to heavily recommend and also realised I had gathered a nice set of quotes from ffffound.

Event
The Hide&Seek pervasive games festival takes place from Friday 31st July to Sunday 2nd August [2009] in and around the Royal Festival Hall, and is free. See the games they plan to run across the three days here.

I definitely plan to attend, so let me know if you are interested. It’s like a more polished version of the Sandpit event that I went to a few weeks ago. To get an idea of what it’s like, see my blog post.

[Do note that this is a re-posted blog version of an old email. At the time of posting, the next Hide&Seek Sandpit event will happen on Thursday 4th August 2011 – T.M. 24/07/11]

Films
I saw Evil Dead 2, which like Evil Dead is less like a horror film and more like a nightmare you have after watching a horror film.

I saw Coraline, which was very beautifully made, but somehow not quite as neat and satisfying as the novel.

I saw Tokyo, which was a collection of 3 very strange short films about Tokyo, and is the kind of thing I would like to see a lot more of even though I only really liked two of them.

But more importantly, I saw Sita Sings the Blues, a feature-length animation by Nina Paley, which is a) good and b) free to download.

It covers a certain episode from the Hindu epic Ramayana, uses a range of animation styles, some songs from the 1920s, and includes debate between storytellers about different versions of the story, which I particularly liked. You can see some of this in the trailer:

Different ways to watch it can be found here, including just watching it on YouTube:

The story of how the film interacts with copyright law is also interesting.

Quotes
FFFFound!” is an invitation-only site where select graphic design types post up images they like (warning: NSFW about 5% of the time). Sometimes the images simply depict a quote. Here’s some of my favourites, alongside some other quotes:

1) “If you can’t explain it simply, you don’t understand it well enough.” – Einstein

2)

3)

I think the fact that the source of this quote is unknown strengthens it. As soon as you attach a name to it, the question of that person’s own mortality suddenly clouds the quote’s otherwise clear, zen-like nature.

4) (Actually this one is not from ffffound, or particularly a quote). In a discussion about the technological singularity (advances in technology accelerate, we invent self-improving AI which improves itself at an accelerated rate, until a day comes in which so many advances are made it is impossible to predict what might happen after), Vernor Vinge suggested that the super AI would not consider humans to be worthless and wipe us out, since it should see us as a useful backup.

When Steward Brand of the Long Now asked how long a dangerous intermediary period might be during which AI’s would be “smart enough to exterminate us but not yet wise enough to keep us around”, Vinge answered:

About 4 hours.

So watch out for that.

5)

6) Georges Perec:


For the full quote go here. [You may notice that many questions/puzzles that appear on Things are in this spirit. – T.M. 24/7/11]

Last week’s puzzle – CC list issues
Given the lack of response on this issue and no fully satisfactory solution being evident, I’m going to go with the least bad solution as I see it: one CC list for people at RAPP, one for everyone else. We’ll see how that goes.