Skeptics with a K: Episode #251


Lie detectors, HPV, pregnancy, and llamas. Plus Earth Domes, Frank Spencer, and seven-day creation. Cracking the Crystal Maze, it’s Skeptics with a K.

Get your tickets for MSSX today. Featuring Simon Singh, Britt Hermes, Emma McClure, Chris French, Meirion Jones, Dave Alnwick, and our own Dr Alice Howarth! July 6th. Liner Hotel, Liverpool. Be there!

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  1. #1 by Tom Williamson on May 31, 2019 - 10:32

    Guys, guys, guys. Crystal Maze aficionado here. I hate to spoil anyone’s Crystal Maze experience, but the little clip of Richard O’Brien you see at the start was not recorded especially for the Crystal Maze experience, but for a seldom seen Christmas special where he passed the torch to Ed Tudor-Pole. He writes the letter, rides off on a motorbike with Mumsy, then you see a hand enter the shot and take the letter.

    I’m still angry about the new Crystal Maze. Can you tell? http://www.skepticcanary.com/2017/08/28/everything-wrong-with-the-new-crystal-maze/

  2. #2 by Muz on May 31, 2019 - 20:57

    Irrelevant trivia: Trish Goddard worked in Australia for a time as a newsreader and host on Play School of all things. So here second career showing up in Shaun of the Dead is probably doubly weird for some.

  3. #3 by Chris on June 3, 2019 - 21:36

    Finance professor Gayle DeLong has provided much hilarity with her “vaccine research.” She came out of the gate with the premise that every child in a school getting Speech/Language Intervention services was actually autistic. Um, yeah… no. Stuttering, hearing loss, aphasia from stroke, dysarthria from cerebral palsy and on and on and on are not part of the autism spectrum.

    Gayle DeLong does a parody of actual research.

    My youngest is in grad school to be a speech/language pathologist with a specialty in voice disorders, especially after throat surgery. So I get to hear about things.

  4. #4 by Cappy Charlie on June 9, 2019 - 13:01

    Interesting piece on polygraph testing. It would be good to hear what Emma has to say on the subject given that some offenders in England and Wales have the mandatory undertaking of polygraph tests as one of the conditions their release from custody. In these cases it would also be very interesting to know who was administering the test, as someone with an existing knowledge of the offender may well be less than impartial in their interpretation of the data.

  5. #5 by Martin on June 17, 2019 - 00:01

    Isn’t a vaccine that is only 70% effective almost completely useless for most women? From basic probability maths even if you had just two sexual partners your coverage will be just 49% (0.7 x 0.7). Here in New Zealand, the *average* woman has had at least 20 different sexual partners. So the chances of being exposed to the 30% of cancer causing HPV not covered by the vaccine is 0.7 ^ 20 = 99.99%. This does assume that almost everyone carries HPV of some sort, which obviously isn’t true, but even with that modifier I doubt this vaccine will have any point whatsoever for the average woman. I guess time will tell if we do or don’t see a massive drop off in cervical cancer rates.

  6. #6 by Chris on June 19, 2019 - 23:27

    It is better than the 0% of not getting the vaccine. Do you mean the 70% of the TYPES of HPV virus? That is completely different than vaccine effectiveness.

    Also, you need a citation for that data on the average woman in New Zealand.

  7. #7 by Martin on June 21, 2019 - 00:29

    No, Alice clearly said in the show that the vaccine only immunises against 70% of HPVs. My mathematics is based on the chances of being exposed to the 30% that isn’t vaccinated against – i.e. almost certain if you have a lot of sexual partners like NZ women, thus rendering the vaccine almost completely useless imo.
    Here is a link to sexual partners in New Zealand:
    http://www.stuff.co.nz/life-style/22444/Kiwi-women-most-promiscuous-in-the-world

  8. #8 by Chris on June 24, 2019 - 18:02

    A news article is not a scientific nor statistical citation. That looks exactly like the dodgy advertising click bait surveys that Marsh often talks about. The big hint is that it was compiled a company that makes condoms, not any kind of public health agency.

    Try again. Look for it in the PubMed index and not in click bait news articles.

  9. #9 by Martin on June 27, 2019 - 08:33

    Chris, you’re barking on about an article I have now cited, but not remotely addressing the elephant in the room. Even just two partners renders the vaccine at <50% efficacy. 5 partners and you're at 17%. 10 partners you're at <3%. The cited article isn't really my point of discussion (although as a NZer I can anecdotally vouch for its accuracy). Vaccinating men is completely pointless too (and won't change the maths), since you're still vaccinating against the same 70% of HPVs.
    Now there is a possibility that the 70% of cancer causing HPV's that are being vaccinated against represent 99+% of the carriers (i.e. the 30% not covered are very rare HPVs). But if that is the case, this vaccine isn't really being marketed in it's best possible light.

  10. #10 by Alice on June 27, 2019 - 16:21

    Hi Martin,

    What you’re missing here is the biological understanding of how those 2 viruses cause over 70% of cervical cancer cases. This is not a risk per virus or even risk per sexual partner, this is a lifetime risk. The additional partners you’re adding in are already accounted for in that 70%.

    What we know (and I said in the show) is that 70% of cervical cancers are caused by infection with two viruses (which the HPV vaccinates against – it also vaccinates against some other viruses that can be associated with cancer but have a lower risk associated with them). Part of that is due to just how common those two viruses are and how many sexual partners you might encounter carrying that virus. Your risk of exposure is part of the cause. You can’t assume that your risk of exposure to every type of HPV is identical so you can’t just compare one virus with another using probability in that way – it’s way more complicated than that. Exposure relates both to how many people carry the virus, and how transmissible that virus is which is different for every type of the virus.

    Secondly, you’re not accounting for other causes of cervical cancer – although viral infection is the largest cause of cervical cancer, it is not the only cause, that remaining 30% isn’t all about viral exposure. And in fact it might also be the combination of any one virus, and another factor such as smoking which is known to be related to an increased risk in cervical cancer.

    Finally, it’s all about understanding the cost versus the benefit – and I don’t mean a financial cost necessarily. If 70% of all cases of cervical cancer are related to just two viruses, even if we do assume that the remaining 30% *are* all related to the other viruses – that’s 30% spread (not necessarily equally) over another 98+ types of the virus (there are over 100 types of HPV) which means *even* if it were split equally (it isn’t) that would be like 0.3% reduction in risk for every virus you add to the vaccination. It just isn’t worthwhile, the 70% is already making a huge difference. The remaining viruses have both a lower risk of causing cancer and are far less common in the general population.

    And let’s not forget that not every sexual partner you encounter will carry even one of those HPV strains.

  11. #11 by Chris on June 30, 2019 - 06:39

    Martin, as you can see I did not address the “elephant in the room”, but the “bull in the china shop” that was the “survey” about Kiwi women which was based on an online survey by a condom company. Personally, I think that you did that was hilarious.

    I knew Alice would be better suited to explain the epidemiology (even though I knew it “kinda”, but she is much more qualified… and to be fair: you asked her directly). Thank you, Alice!

    As someone who was once an applied mathematician, though in structural dynamics not epidemiology, I still believe 70% is much better than 0.0 %. Prove me wrong! 😉

    As an aside, as soon at the HPV vaccine was approved for males in the USA I made sure my son in college got it, at least the first dose. He followed up on his own to get the next two doses. I know because I paid the part not covered by insurance. (stupid &^%$#! USA health insurance !!!)

    Apparently he got some epidemiology math while getting a minor in applied math along with his math degree. Yeah, the numbers sometimes work out. All hail Sir Ronald Ross!

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