Rentokil make dodgy claims about imaginary bugs

March 12th, 2010 by Ben Goldacre in bad science, churnalism, models, numerical context | 38 Comments »

Ben Goldacre, The Guardian, Saturday 13 March 2010

2,000 bugs taking a ride in every train compartment” said the Daily Mail. “Cockroaches cluster on trains“, scuttled the Telegraph. “Commuters share trains with 1,000 cockroaches, 200 bedbugs and 200 fleas” said the Evening Standard. The figures were all very specific and very frightening.

“Rentokil say they also discovered that a bus was home to 500 cockroaches, along with dozens of fleas and bedbugs,” explained the Standard. Those disgusting trains are even worse. “Research by pest controllers Rentokil shows that, on average, a single train compartment houses a staggering 1,000 cockroaches, 200 bed bugs, 200 fleas, 500 dust mites and 100 carpet beetles,” said the Mail.

These figures are very specific, and they do all sound a little bit on the high side. Where did they come from? “Staff at Rentokil sprayed insecticide throughout the carriages of a train and a bus and then counted the bodies of insects.” said the Standard. Savvas Othon of Rentokil explained in the article: “The bus we studied was within the M25”.

But Transport for London say they’ve had no contact with Rentokil, and that no such study has been done on their vehicles. I asked Rentokil for more details on what vehicles they had studied, where, and how, what was counted, how the bugs were collected, and so on.

After a bit of prodding, their PR company Brands2Life explained how these bugs were counted. No buses were studied, and no trains were studied either. How did people get the wrong end of the stick? What was that about with Savvas Othon? I have no way of knowing. Brands2Life and Rentokil both declined to show me what they sent to journalists, but in any case, contrary to what was said earlier, wherever it came from, these numbers did not come from measurements and counts, they are actually based on a “theoretical model”.

Models are handy. They’re a simulation of reality, based on a series of assumptions. Rentokil’s model for the number of bugs on trains and buses made some interesting assumptions, and you will have your own view on whether they make for a reasonable approximation to the real world.

They assumed, for example, that the railway carriage or bus was left alone, by itself, in isolation. They assumed this isolated carriage was helpfully furnished with a plentiful food supply. They assumed that the ratio of male and female bugs was perfectly optimal for breeding.

They assumed – surprisingly for anyone involved in modelling populations, surprisingly for anyone, really – that the population of bugs would be left entirely unchecked, with no external factors to control the mortality rate. They assumed that the siding or garage was controlled at a constant temperature all day and night, with no extremes, they assumed there were no trampling commuters, no cruel vaccum cleaners, no anything. In fact they assumed there was no cleaning, ever, and no passengers, ever. This was their model of insect populations on commuter vehicles.

“On the above basis” Rentokil’s PR explained to me: “it is possible that the stated numbers of cockroaches and bed bugs/fleas could live on a train carriage or bus.”

You will have your own view on whether you could trust an organisation that makes assumptions like these in estimating the “average” population of a bug. But it’s somehow unseemly that Rentokil, a company with £2,356m revenue, a 54% increase in profits in 2009 to £166m, and poised to pay £90m in bonuses to its top 3 executives, feels the need to make everyone afraid of public transport on a PR whim. There is also the ugly thought that Rentokil will do more business if they can make everyone scared of bugs on the bus.

And on March 2nd, the day before the cockroaches press release, Rentokil announced the single biggest ever contract in the history of their business: £200m over 5 years with London Underground.

Please send your bad science to

Appendix 1: twits

Rentokil have engaged in some seriously surreal PR activity on Twitter during my digging on this story, largely around whether they would give me the information they sent to journalists. The best bits were when they tried to suggest that they were actually being all open and stuff.

You can pick up some threads here (read backwards I guess), and if there’s a better timeline of quotes anywhere I’ll link to it. This was a textbook case of PR fail, but I’ll spare the details, as it’s possible you had to be there in real time and with popcorn. The slightly odd and chastising tone of this post from Rentokil’s blog might help you form your own opinions about the person who has been left in charge of the Twitter login for a £2.4 billion corporation.

Appendix 2: PR

In the generality (and I mean that very seriously, I’m not talking about Rentokil or my article here, but the wider issue which comes up a lot) I think there are a few things that companies and PR people need to learn about the internet. When there was only olde worlde large scale media, covering only big stories, where space is short, and the product is a single final publication on paper, PR is different. Even in a truly dismal situation, you can often do a bit of superficially plausible PR that someone will stick on the end of their mildly critical article, and then you can run for it. If your response turns out to be flimsy, the paper won’t bother coming back at you, or returning to the issue, because that wouldn’t interest a million people.

With the internet, page space is infinite, and people will post any old nonsense on the grounds that it might be interesting to someone somewhere (and I’m very glad of it).  There are bloggers, of course, who will get inexplicably fascinated by a single issue, and follow-up every development, no matter how obscure. But there are also random passers-by, who might use Google to double check your utterances on Twitter, in 10 seconds, while they wait for the kettle to boil, just out of interest. Then they might post the results, with a single keystroke, on Twitter, in a blog comment, just because it adds a little to the story, and someone else might find that, and build on it, and so on. I’m rambling, but I do think it’s interesting how the web makes the environment very different for everyone in PR who hopes that vagueness and disinterest will smooth over their rougher edges.

Update Friday 21:30

Someone has just sent me this:

Interestingly, I’ve also been contacted by someone from a major public transport organisation. They told me that Rentokil promised to clarify on these foolish figures to journalists over a week ago, when the story was in the news, but then they didn’t. So it’s fun to see that Rentokil were suddenly able to post and clarify these issues. Late. One Friday evening. A week and a half later.

If you like what I do, and you want me to do more, you can: buy my books Bad Science and Bad Pharma, give them to your friends, put them on your reading list, employ me to do a talk, or tweet this article to your friends. Thanks! ++++++++++++++++++++++++++++++++++++++++++

38 Responses

  1. Synchronium said,

    March 12, 2010 at 9:47 pm

    Awesome. I watched this pan out live. Glad to see some more internet justice. Reminds me of the Neal’s Yard fuckup.

    So, when can we expect a column on mephedrone, the biggest media shitstorm of the year? I’m sure there’s some interesting facts you could tease out of that…

  2. kateweb said,

    March 12, 2010 at 9:59 pm

    It is indeed fun to see how fast they can suddenly clarify! And that their “apology” is still linking to a press release that doesn’t contain any of the relevant figures sent to journalists, still less what context they were put in (i.e. model v “we checked actual buses”). Terrible when the media misleads people….

  3. DarrenG said,

    March 12, 2010 at 10:03 pm

    What’s maddening is that they can seed these stories in the first place. Either Rentokil, the PR company or the Journo’s who picked up the story have basically invented a problem that does not exist and as a result doubtless caused some to worry about using public transport.

    It’s time we started holding these companies to account for such actions and indeed the newspapers that are happy to invent or modify a story to make a better headline or to fit their agendas. Some newspapers are about as newsworthy as Viz these days!

  4. Daniel Mcskelly said,

    March 12, 2010 at 10:13 pm

    “our PR Agency released numbers calculated on a hypothetical worst case scenario”.

    Love the wording on their clarification. If you’re going to apologise, apologise, don’t blame it on your flacks.

    Ahh well, it was probably worth the misinformation just for yesterday’s Twitter debacle, and the downright bizzare blog post about their twitter strategy. I really feel like I’m engaged in a conversation with Rentokil now. Just like we’re at a party together. Wooo!

  5. maibee said,

    March 12, 2010 at 10:17 pm

    But the warping of information/history continues. In the link from their blog in Ben’s update they refer to the ‘original press release’ and then give a further link to guff just about the Entotherm process. Not the numbers etc. So not the original press release…? *Shrugs shoulders

  6. nongovernmentalindividual said,

    March 12, 2010 at 10:27 pm

    Makes me wonder whether there was even any model… or just a bit of guesswork. The numbers do look a bit round for a model.

    Also, this would be merely a case of economy with the truth and shoddy journalism if it wasn’t for Rentokil’s claim to have actually counted real dead things – an out and out lie

  7. bravante said,

    March 13, 2010 at 12:29 am

    According to our model, we can safely assume that Rentokil is full of crap

  8. pidg said,

    March 13, 2010 at 12:32 am

    In case anyone still isn’t clear about how PR agencies work, it starts with a brainstorm: “What can we say/do that will get attention?”, then works backwards from there (“How can we make the facts and figures fit our exciting idea?”), not the other way round. If you investigated all stories based on agency press releases, you’d probably find holes in most of them.

  9. CoralBloom said,

    March 13, 2010 at 1:05 am

    So Rentokil make things up?
    Right. So if I ever come across a bug problem and need professionals who would I call? Someone who makes things up, like an astrologer, or someone who deals with real problems………

  10. loosewire said,

    March 13, 2010 at 1:27 am

    Has anyone managed to locate the original email/press release that the Mail/Standard/Telegraph used for their stories? That seems to be the missing piece of the puzzle.

  11. Luciani said,

    March 13, 2010 at 8:09 am

    PR tactics remind me of a proverb from where I’m from:

    “It’s easier to gain forgiveness than to gain permission”

    Once the cat’s out the bag; “Oops! Our bad!” but the fact is that many people have heard this drivel and aren’t exactly going to be following it up on Rentokil’s homepage.

    I am also endlessly frustrated at retractions and apologies printed in the newspapers. A front page article claiming something false, will have a retraction and apology printed on page 8 in the far left hand corner. Differs in quality of newspaper’s journalistic integrity.

    The fact is that is much more likely that people will be telling others this story about how the public transportation is grossly infested, rather than the truth being known in the general public that this is NOT the case.

    PR stunt: success.

    Journalism has such a massive amount of responsibility inherent with it that I sometimes feel like we’ve left one of the most important jobs on the planet to a group of chimps on typewriters.

  12. andybrice said,

    March 13, 2010 at 8:16 am

    PR – where people go when they are too dishonest to be in sales and too stupid to be in HR.

  13. BobP said,

    March 13, 2010 at 9:17 am

    Interestingly, in India the train carriages are maintained at a fairly constant & warm temperature, and cleaning is sometimes sub-optimal 😉

    There’s a species of small cockroach which just loves Indian railways. Maybe the research was done by Rentokil’s indian branch?

  14. jodyaberdein said,

    March 13, 2010 at 9:36 am

    Shame. I have always thought of Rentokil as being an honest, nice, friendly company you know.

  15. adambanksdotcom said,

    March 13, 2010 at 10:34 am

    I posted a comment on the Rentokil blog at 11:33 last night. As of 10:33am, it’s still “awaiting moderation”. It is the weekend, I suppose – they’re probably enjoying a well-earned rest.

    (The comment, for the record:

    So, let’s be clear. Your PRs seeded a story about how many bugs existed on public transport in London – a story guaranteed to send shivers up the spine of every commuter. Turns out not only was the data not based on any research into public transport in London, it didn’t refer to any real world scenario at all, only a set of obviously invalid assumptions. It was, in fact, made up.

    And your idea of “an apology” for this is to dance around Ben Goldacre all day on Twitter, hoping the whole issue will just magically go away, and finally post a blog entry that tries to make it sound as if there was something reasonable about releasing junk data to journalists, then links to a press release that doesn’t even contain the claims referred to, which, as Goldacre has already established, were made in separate communications that you decline to make public.

    All this, you say, was to publicise “a new process we launched – and are very excited about – to combat bed bugs and cockroaches”. Those same bed bugs and cockroaches that, we now know, may exist only on “a totally theoretical basis”.

    You can hardly blame anyone for wondering: is London Underground paying you £200m to kill real bugs, or imaginary ones?

    (Comment awaits moderation) March 12, 2010, 11:33 pm)

  16. adambanksdotcom said,

    March 13, 2010 at 10:35 am

    I posted a comment on the Rentokil blog at 11:33 last night. As of 10:33am, it’s still “awaiting moderation”. It is the weekend, I suppose – they’re probably enjoying a well-earned rest.

  17. Grendel said,

    March 13, 2010 at 10:41 am

    It has been a very long 15 minutes since I finished reading this post and started work on my very own entomological model – this time for application in the offices of pest control companies.

    I have assumed that in any given office there is a supply of insect foods that includes crumbs dropped in keyboards and skin flakes from a standard workplace density of one person per 15m squared.

    By my calculations the offices of any pest control firm are infested with over 10,000 cockroaches, 32,000 ants, and sundry parasitic organisms that are overpaid and generally incompetent to carry out PR work.

  18. vashti said,

    March 13, 2010 at 12:31 pm

    As far as transcripts go, try these:

  19. markus.readus said,

    March 13, 2010 at 12:53 pm

    Great post Ben, thanks!

    My research rests very heavily on the use of modelling and simulation to investigate immunology. Simplifying assumptions are an integral part of the process. Appreciating how to relate the results of your abstraction of the real world back to the domain of interest is important, though difficult. And communicating the limitations of your work (since it is an abstraction) is a fundamental part of using it in a real scientific context. From what I gather the model created would have been useful for entirely nothing, other than a PR stunt. The people who created this model, and then blasted the media full of complete b*llocks should be ashamed of themselves: not only does it demean the hard work of the modelling and simulation community who are trying to make these techniques an integral part of scientific research, but announcing such spurious results out of context is (in my book) equivalent to “lying”, and is hence immoral.

  20. Jeesh42 said,

    March 13, 2010 at 1:18 pm

    Great! Rentokil badmouths London Transport with made-up data and then has the cheek to blackmail them into becoming a major client. What an exceptionally nasty way to do business.

  21. Andy Mabbett said,

    March 13, 2010 at 1:53 pm

    I’ve submitted an FoI request about this, to TfL:

  22. RogerMexico said,

    March 13, 2010 at 2:36 pm

    If anyone does find the urtext Press Release, it’ll be interesting to see if the Mail’s ridiculously low number of 500 dust mites are on it. If they are, it shows the details haven’t been anywhere near anyone who knows what they’re talking about. If not it’ll be an almost unique example of the Mail making up something that underestimates a (not very) scary number.

  23. Doc_Daneeka said,

    March 13, 2010 at 9:07 pm


    Your comment has appeared, but appears to have the last para missing:

    “You can hardly blame anyone for wondering: is London Underground paying you £200m to kill real bugs, or imaginary ones?”

  24. Bexley said,

    March 13, 2010 at 10:46 pm


    Clive Thompson went on to head Farepak after leaving/getting fired from Rentokil. He was in charge when Farepak collapsed.

  25. MK01 said,

    March 14, 2010 at 5:18 pm

    Rentokil used to be a client of mine when I was a banker a few years ago. Every time I had to visit their HQ (then a ridiculous stately home-type place in Sussex), I would have to traipse outside across the mud in my high heels to go and see the “rat pen” – a wire mesh enclosure where they bred rats to practise extermination techniques on. They were a very odd bunch of people! and horrible to have as a client – very much a bullying culture; if something goes wrong, make sure someone gets royally bollocked, at fault or not. Culture *might* have changed since those days……

  26. Hadenuff said,

    March 15, 2010 at 9:59 am

    I use the “Bad Science” blog to inform/educate/.entertain my 11- 18 year old students, as a small contribution against the intellectual pollution to which they are constantly exposed. I can’t do this if people leave comments such as Synchronium’s “Neil’s Yard fuckup”. More than my jobs worth, etc. A plea to keep it “clean”, so I can continue to show it in school.

  27. phayes said,

    March 15, 2010 at 4:39 pm


    Would something like this help?

  28. philbo said,

    March 15, 2010 at 5:34 pm

    They should have said there were bugs in their modelling software


  29. timheyes said,

    March 15, 2010 at 10:52 pm

    At the risk of starting a flame war….

    Replace Rentokil with IPCC and bugs with catastrophic climate change. How is it that you can be so insightful on the one hand and so blind on the other, Ben?

  30. lasker said,

    March 16, 2010 at 2:11 pm

    I find it difficult to believe they had a “model” at all.
    Whilst many of the figures seem high, surely the figure of 500 dust mites is vastly low. I reckon all these figures were just made up after a liquid lunch.

  31. kimaldis said,

    March 16, 2010 at 3:51 pm

    I began to suspect that Rentokil were idiots when they charged me two grand to wreck two rooms in my house in a humungously botched attempt to prevent what they said was rising damp but that actually turned out to be falling damp. We had a proper damp company fix it for us for half the price. Morons to the bitter end.

  32. Shareholder said,

    March 17, 2010 at 5:47 pm

    I heard you on the radio today.

    Not only is the railway carriage story a scam, the main reason for their email announcement is also untrue. There is nothing new about killing insects with heat, these people have been using the same method for the past 18 years!

  33. Guy said,

    March 22, 2010 at 3:10 pm

    Interesting the way Rentokil run their website.

    I posted the following comment on their blog-
    “As a shareholder of Rentokil I suppose I should be pleased at the publicity. I’m not so sure though that there is no such thing as bad publicity.

    Slagging off some of the major companies you hope to work for by falsely saying that public transport is filthy could be an own goal. If I was awarding contracts for treating buses or trains then Rentokil would be the last people I would now approach.

    I suspect that world isn’t entirely made up of uber-cynical PR types who don’t care anything for truth.”

    This was posted 4 days ago but hasn’t appeared and has had 7 comments added after it but mine is being delayed whilst moderated. Strange sort of censorship.

  34. johnnye87 said,

    March 24, 2010 at 2:43 am

    Hah, brilliant.

    “2,000 cockroaches? My God, they must never clean those buses!”

    “Ah. Actually, that figure is based on a hypothetical model that assumes they never clean the buses.”


  35. waveydavey69 said,

    March 26, 2010 at 11:19 am

    I worked on buses for about 3 years, servicing, repairing and MOTing I have never seen a cockroach on a bus, inside, outside or underneath. I once saw a cockroach on the same day I had worked on a bus maybe that would count as relevant data! my cat scratched it’s ear which may have been a flea on the same day I worked on a bus etc..

  36. wwdlu101 said,

    April 1, 2010 at 10:13 am

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  37. kylemcinnes said,

    April 4, 2010 at 4:19 am

    Consider a pointlike bus in a vacuum, radiating bugs isotropically…

  38. TheLancashireman said,

    April 12, 2010 at 9:52 am

    It seems to me that what the bascientists have discovered here is the maximum possible number of said pests that can possibly exist on any bus or train under any circumstances. I find their figures comfortingly low 😉