Dodgy stats on the Gateway Hypothesis

Once upon a time the Gateway Hypothesis* related to the fact that people who smoked cigarettes might at some point attempt to consume marijuana and/or cocaine. Cigarette consumption has collapsed in many countries, yet people still seem to consume marijuana and cocaine. So now the Gateway Hypothesis is that people who vape (i.e. consume electronic cigarettes) might take up the consumption of combustible cigarettes.

We are treated to shock-horror headlines such as:

That’s from The Australian – one of the more sensible and least hysterical media outlets.

Vaping is a “gateway” to conventional smoking with those using e-cigarettes three times as likely to take up tobacco, a study reveals.

“We found non-smokers who use e-cigarettes have around three times the risk of taking up regular smoking than non-smokers who have avoided e-cigarettes.”

The latest research, a joint project by the Australian National University and University of Melbourne, was commissioned as part of the so-called “Vaping Inquiry” agreed to by Health Minister Greg Hunt in 2018.

Well, it turns out that wasn’t an actual study, but rather a meta-study performed by researchers at the ANU and Melbourne Uni. The paper can be found here.

I have many criticisms of that paper (and other similar studies) but here I want to highlight some statistical sleight of hand that is going on.

This sleight of hand is well illustrated by a paper published in Tobacco Control in 2018. The table below is reproduced from Best et.al (2018) in total. Note that the definition of having smoked a cigarette is having taken ‘just one or two puffs’.

Best et.al (2018) interpret the table as follows: Of 2125 students in the sample, 183 students consumed e-cigarettes (169+8+6 = 183). Of those 183, 74 students also consumed combustible cigarettes. Therefore 40.4% (74/183) of Never Smokers who had consumed e-cigarettes went on to consume combustible cigarettes. By contrast only 12.8% of Never Smokers went onto consuming combustible cigarettes (249/1942).

That is one interpretation of the data. That interpretation, however, is highly misleading. It artificially partitions the students into combustible cigarette consumers and e-cigarette consumers, and then investigates any overlap. It assumes that which is yet to be proven. The Gateway Hypothesis suggests: those individuals who had consumed e-cigarettes are more likely to subsequently become consumers of combustible cigarettes. The important distinction here is: more likely than whom? There are four groups of students in the sample. Those students who never consumed either a combustible cigarette or an e-cigarette. Then we have students who consumed combustible cigarettes who never consumed e-cigarettes. The existence of these two groups of students provide evidence against the Gateway Hypothesis. Then we have a group of students who consumed e-cigarettes who had never consumed (even took a puff or two) of a combustible cigarette. The existence of this group of students is, at least, inconsistent with the Gateway Hypothesis. To the extent that any of these students may well have become combustible cigarette consumers, but did not, this group of students would provide evidence that rejects the Gateway Hypothesis. Unfortunately, due to the casual empiricism that is so common in this literature, that interpretation of the data is not tested by Best et.al (2018) or any other  researchers in the field. Finally there is a group of students that consumed e-cigarettes that went on to consuming combustible cigarettes (or, at least, had a puff or two of a combustible cigarette).

To illustrate the inadequacy of the interpretation of the data in the table – the data in the various underlying studies are often presented in a confusing and misleading manner – I have summarised Best et.al’s (2018) table 2 as below:

Of the 2125 students in the sample, 1693 had never consumed either a combustible cigarette or an e-cigarette. That is 79.67% of all students. 249 students had consumed a combustible cigarette, but had not consumed an e-cigarette – that is 11.73% of all students. Then 109 students had consumed e-cigarettes, but had not consumed combustible cigarettes – that is 5.13% of all students. Then 74 students had consumed both combustible cigarettes and e-cigarettes – that is 3.48% of all students.

Yet by carefully partitioning the student sample, Best et.al (2018) are able to inflate a figure where 3.48% of students use e-cigarettes before combustible cigarettes into a result consistent with the Gateway Hypothesis. If we look back to the original Best et.al (2018) table, we see that only four students who had regularly consumed e-cigarettes (weekly) went onto having had a puff (or two) of a combustible cigarette. That is 1.2% of all combustible cigarette consumers and 0.19% of all students. Who can even tell if those four students had gone on to being regular combustible cigarette consumers? The Best et.al (2018) summary statistics are too opaque to reveal that (important) detail

When viewed in this light, the “evidence” for the Gateway Hypothesis is very weak. The analysis that shows otherwise is contrived to show a result that simply cannot be supported by the data. The Best et.al (2108) study, however, is not an outlier. It is not somehow an anomaly. It is typical of the literature.

To demonstrate this point I partially reproduce table 2 from Soneji et.al (2017) below. The first three columns are directly reproduced. The first column shows the study being referred to, the second column shows the probability of an e-cigarette user taking up the consumption of combustible cigarettes, while the third column shows the probability of a non-e-cigarette user taking up the consumption of combustible cigarettes. The results appear to be very similar to those reported in Best et.al (2018).

In order to establish the veracity of those data I investigated the summary statistics of each of the seven papers. In the case of Miech et.al, interpretable summary statistics were not included in the study. Similarly in the case of Wills et.al, I could not sensibly interpret the summary statistics that they did report. In the other five instances, understanding and interpreting the summary statistics was a non-trivial task. I submit that the reporting on summary statistics is deliberately opaque in order to mask to underlying reality that consuming e-cigarettes is not a gateway to the consumption of combustible cigarettes. In each study I attempted to establish the number of combustible cigarette users, the number of e-cigarette users, and the number of non-e-cigarette users. The results of that exercise are shown in the final three columns of the table.

Looking at the totals row, across the five studies where I was able to get meaningful summary data, 712 individual became combustible cigarette users, of those 183 had initially consumed e-cigarettes (183/712 = 25.7%). That means that 74.3% of individuals who became combustible cigarette users did so directly without first consuming e-cigarettes. That result, however, is distorted by Barrington-Trimis et. al. This is the only underlying study that actually provides unambiguous support for the Gateway Hypothesis. This study has an astonishing small sample size of 298. In the absence of that outlier study the percentage of individuals who became smokers after having consumed e-cigarettes falls to 19.5%. That means that over 80% of individuals who become combustible cigarette consumers did not do so after consuming e-cigarettes.

The statistics demonstrating a Gateway Hypothesis are dodgy. The fact is that the evidence supporting such a gateway is very weak. Worse, the hypothesis that vaping is an exit from smoking combustible cigarettes is simply not being tested.

Anyway – my friends at the Consumer Choice Center have just published two papers (one for Australia and the second for the EU) where I spell out this sleight of hand and poor hypothesis development in greater detail.

*Some readers will recognise the Gateway Hypothesis as being a slippery slope argument.

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32 Responses to Dodgy stats on the Gateway Hypothesis

  1. Nob

    Doesn’t pass the pub test. I know loads of smokers, in Asia and Europe, and never met a vaper who wasn’t first a smoker. For them it’s a gateway *out*.

    The big and only exception is cannabis vapers.

  2. C.L.

    Masterful work, Sinclair.

    Yet by carefully partitioning the student sample, Best et.al (2018) are able to inflate a figure where 3.48% of students use e-cigarettes before combustible cigarettes into a result consistent with the Gateway Hypothesis.

    We seem to be entering an era where the scientific/statistical ‘truth’ is manufactured according to political righteousness rather than objective, quantifiable facts.

    The anti-smoking lobby simply hates vaping because they see it as a poke in the eye to their own authority; to their own obsessive dislike of the general habit of inhaling and puffing a substance. They easily captured and manipulated Greg Hunt, of course. Until June, he was set to impose $200,000 fines on anyone who imported liquid nicotine.

  3. Nato

    Statistics are a gateway to calculus.

  4. Roger

    Worse, the hypothesis that vaping is an exit from smoking combustible cigarettes is simply not being tested.

    Purely anecdotal, but no. 2 son has successfully exited cigarette smoking via vaping.

  5. David Brewer

    Nob is right and his argument undermines all studies in this area.

    As a rule, people vape in order to give up smoking. Vaping is sold as a method of giving up smoking. So it is extremely unlikely that non-smokers would first take up vaping, and then take up smoking.

    Any survey would have to ask very specific questions about the timing of the two events (taking up vaping and taking up smoking as regular habits) to demonstrate the probability of vaping leading to smoking. There is no evidence that Best et al. have examined the studies from this point of view.

    And even if there were evidence that the odd person first vaped, and then smoked, that would hardly be a serious argument against vaping if vaping allowed many more people to stop smoking, and that improved their heath.

    Instead, Best et al. shows bias against e-cigarettes by making claims casting doubt on their effectiveness which fall over once you realise that vaping is basically a means of giving up smoking and is therefore almost always used by someone who was previously a smoker.

    For example, they say that “Former smokers using e-cigarettes have over twice the odds of relapse as non-e-cigarettes users.” Well, what do you expect? E-cigarette users are smokers trying to give up. Is it any surprise that they are twice as likely to start smoking again as ex-smokers who have already given up? And by the way, how many of those confirmed ex-smokers managed to give up by using e-cigarettes?

    Ditto for the similar statement that “Among former smokers, smoking relapse was higher in e-cigarette users versus non-users” or for the claim that “non-smokers who use e-cigarettes are consistently more likely than non-e-cigarettes users to initiate combustible cigarette smoking and become current smokers”.

    Another problem is, even if you find a few people who first smoke e-cigarettes and then go on to smoke regular cigarettes, does that really prove that without e-cigarettes those people would never have smoked? I doubt it, for you are dealing with a population that wants to smoke something. It is more likely that, if e-cigarettes were banned, these people would become regular smokers, which would be far worse for their health.

    And beyond these conceptual problems, just look at the sample in the Tobacco Control paper. At first blush, it seems a decent size (2125 individuals), but 80% of them have never smoked or used an e-cigarette, so what do they prove? The population of serious interest for the purposes of that study was only those individuals who had made some meaningful use of e-cigarettes. I make this a grand total of 14 people. The other 2111 had either never used an e-cigarette or “only used them once or twice” – i.e. had a puff or two to see what they tasted like.

    The only value of the Best et al. study may be that, by trawling the world literature on this topic and not finding anything convincing, they have demonstrated that there is as yet no serious evidence of the Gateway Hypothesis, despite their confected case to the contrary.

  6. a happy little debunker

    Must protect … insane Tobacco excise … by forcing vapers onto cigarettes…

    (Cheapest packet of fags you can buy is $28.75, remove the GST and excises – the price drops to $3.88)

  7. Some History

    Much information has been passed through the Cat over the last few years to comprehend that Public Health is a major public menace. During the pandemic we got a good look at what happens – extreme control of movements/behaviour of the populace – when Public Health is given free rein over policy/laws.

    Since the 1970s Public Health has become agenda/ideologically-driven in the Eugenics lineage. It will mangle and manipulate information to fit the agenda. The greatest mangler of all is the branch of Public Health, Tobacco Control. The only question to be asked in any “research” appearing in Tobacco Control is how manipulation was effected to arrive at the required conclusion.

  8. mundi

    Out of all the things regulated in my life, why should I care about this?

    Did you know the government regulates how much water a shitter can flush in one go? There is a bigger problem.

  9. Some History

    1

    This is a good thread to leave this information.

    UPDATE

    Last year North Sydney Council introduced a baseless smoking ban for the entire suburb – no smoking anywhere outdoors. At the time it was noted that the Heart Foundation rep had been doing the rounds of city councils trying to convince them to ban smoking outdoors. Long-time professional antismoker, Simon Chapman, was one of the rare critics of the ban, highlighting that such bans have no scientific basis.

    Well, now it’s Melbourne’s turn. Last year the Melbourne City Council banned smoking in the Bourke Street Mall. During the covid “pandemic”, the Melbourne City Council has been very busy on more antismoking. In August the Council banned vaping in all areas that smoking is banned. In September the Council banned smoking in Market Street Park. Baseless and draconian as these bans are, it’s still not enough.

    Here’s Melbourne City Council’s latest globalist brain fart unto the “Therapeutic State”, a variant of Statism in the Eugenics lineage

    The City of Melbourne council is pushing to ban smoking and vaping in public spaces across the CBD within five years.
    The council is also considering outlawing smoking at council-run and permitted events by 2025.
    :

    The City of Melbourne has a vision to become a smoke-free city where everyone can breathe easy.
    We know that smoking is still the biggest contributor to preventable disease and deaths in Australia and there is more work to be done.

    As part of the global Partnership for Healthy Cities network — an initiative of Bloomberg Philanthropies, the World Health Organization and Vital Strategies — we have developed a discussion paper and a draft policy to help us achieve our vision. The draft policy will assist in the planning and delivery of more smoke-free areas and other activities to support people to quit and reduce smoking in our city.

    https://participate.melbourne.vic.gov.au/smoke-free-melbourne?fbclid=IwAR34vsgoITT-XHGH6VnQa4n8BlQeHvapqbzud0AWzv9Wnv2oOJjgE3bxHlw

    Lil Mike Bloomborg is a rabid antismoker. He’s pumped hundreds of millions of dollars into the World Health Organization (WHO) for antismoking purposes. Bloomborg “Philanthropies” also funds “Partnership for Healthy Cities”. Amongst the funders of Vital Strategies are Bloomborg, Bill Gates, Mark Zuckerborg. So, the Melbourne City Council has bought into the unelected and unaccountable globalist WHO/billionaires’ club [deranged] “vision” for humanity.

    https://participate.melbourne.vic.gov.au/smoke-free-melbourne?fbclid=IwAR34vsgoITT-XHGH6VnQa4n8BlQeHvapqbzud0AWzv9Wnv2oOJjgE3bxHlw

  10. Some History

    2

    In anything to do with antismoking, it can reasonably be expected that there’s some major inflammatory junk in there somewhere. Not only is there no scientific basis (i.e., passive smoke “hazard”) for any outdoor bans, let alone smoking bans for an entire CBD or suburb, but the MCC “vision” has another level of junk.

    Having made itself a partner in Partnership for Healthy Cities, the MCC got to select one of 14 interventions to prevent non-communicable diseases and injury. The MCC has chosen option 1 –

    1. Create a smoke-free city
    Introduce, pass and enforce legislation and regulations to make all indoor public places, workplaces and public transport 100% smoke-free

    https://www.vitalstrategies.org/programs/partnership-for-healthy-cities/

    Note that the option concerns indoor spaces. Yet the MCC has done a sleight-of-hand, erroneously turning the focus onto outdoor spaces. And the MCC is pushing the falsehood of protecting nonsmokers from “passive smoke” as a major justification for extensive outdoor smoking bans.

    Advancing the inflammatory propaganda that nonsmokers need to be protected from outdoor “passive smoke” promotes mental dysfunction; it promotes more irrational belief/fear/hatred amongst gullible and already neurotic nonsmokers.

  11. Botswana O'Hooligan

    Reminds me of the ban the Methodist church placed on pre marital sex because it could lead to dancing.

  12. C.L.

    Another problem is, even if you find a few people who first smoke e-cigarettes and then go on to smoke regular cigarettes, does that really prove that without e-cigarettes those people would never have smoked?

    Then there’s the broader question: so what?
    So what if people take up smoking? It’s perfectly legal.

  13. Some History

    Then there’s the broader question: so what?
    So what if people take up smoking? It’s perfectly legal.

    Yep. Somewhere in the late-90s it became accepted that smoking must be eradicated from the world, that smokers must quit, and no-one else should take up smoking. Who decided this? That’s correct: The WHO decided this. The WHO has been prohibitionist since the mid-1970s. Prohibition had no traction in those years. The prohibitionists noticed, however, that if you make it about nonsmokers, it changes everything. Convince nonsmokers that smokers are “endangering” them with their “nasty” habit. So through the 80s and 90s the prohibitionists would claim that they weren’t trying to force smokers to quit. Rather, any antismoking policies that they recommended was solely to protect nonsmokers from the “hazards” of passive smoke.

    “Passive smoke” was simply a means to the prohibition end. By the 2000s, having demonized the tobacco industry and denormalized smoke/smoking/smokers, the time was ripe for the prohibition step. Since the mid-2000s, governments have bought into the WHO’s prohibitionist Framework Convention on Tobacco Control. Since then it has all been about eradicating tobacco use from the world. Progressively greater punishments have been levelled at smokers for their “non-compliance”, including ever-increasing robbery through extortionate tobacco taxes. It’s all bullying by deranged ideologues/opportunists. And the bullies refer to their increasing bullying/punishments as “help”.

  14. Albatross

    Some readers will recognise the Gateway Hypothesis as being a slippery slope argument.

    One word: homosexual activism. Slippery slope is real.

    On this issue, however, vaping is used by people to cut back or quit smoking. The modern health lobby is an undifferentiated temperance movement, and all their pronouncements are moralising and class-contempt under a thin veneer of “muh science”.

  15. Sinclair Davidson

    Out of all the things regulated in my life, why should I care about this?

    Divide and conquer. That is how the nanny state survives.

  16. Siltstone

    It looks like Best et al have found not previously smoking is more of a gateway to cigarettes that vaping is

  17. PB

    I know some people who have used vaping as a gateway to stopping smoking. They now do neither.

  18. Herodotus

    Allowing one troll is the gateway for allowing more trolls.

  19. Entropy

    I just realised that as I have had one or two puffs in my life (out of curiosity) this study would class me as a former smoker.

    Didn’t like it in case you are wondering. Anyway, doing the lords work here, Sinc. Too much dodgy statistical methods go on in Public Health, all to satisfy an agenda. They get away with it because righteous, and while some would think it too trivial to worry about, being able to get away with this poor approach to statistics builds careers and reputations eventually drifts into areas that actually matter.

  20. Dot

    I can’t believe we are having this debate in current year.

    Most of not all drugs should be legalised. The war on drugs is a catastrophic failure and it also fails to account for how psylocibin and THC are better than SSRIs and opiates for example.

    Free thinking and personal autonomy are gateways to a lot of things. Yet, apparently being a handmaiden is an unpopular idea.

    My body my choice? If a woman can have unlimited legal abortions then surely I can slowly kill myself?

    Vaping is virtually harmless and is a harm reduction technology.

    The problem is anti-smokers are religious fanatics caught up in their own synthetic religion of modern day Puritanism.

  21. Arky

    You are overlooking the important data.
    Almost 80% of students have never smoked?
    Gay.

  22. Dot

    Everything is fake and gay now.

  23. Nob

    Dot
    #3678144, posted on December 3, 2020 at 7:15 am
    I can’t believe we are having this debate in current year.

    Most of not all drugs should be legalised. The war on drugs is a

    … is a great enthusiasm for control freaks everywhere actually. Apart from a few select party drugs these Arctic souls want to ban everything. Think Opiates , nicotine, alcohol and eventually they’ll come full circle to caffeine. But then would you unban , say, Thalidomide?

  24. Entropy

    I reckon the modern penitence (sorry temperance) movement will go for vending machines, soft drink and alcohol before they hit caffeine. They actually use caffeine themselves.

  25. This paper looks very much like the many Climate Change papers I’ve read over the years.
    Scientific industrial complex indeed.

    Do you remember how obnoxious ex-smokers were? They would badger smokers about smoking being bad for you and how awful it smelled and tasted.
    Well, ex-smoker vapers are just like that. We recoil at the smell of smoke when we encounter it out and about.

  26. Albatross

    Arky
    #3678147, posted on December 3, 2020 at 7:19 am
    You are overlooking the important data.
    Almost 80% of students have never smoked?
    Gay.

    Never smoked cigarettes.

  27. PB

    “I reckon the modern penitence (sorry temperance) movement will go for vending machines, soft drink and alcohol before they hit caffeine.”

    Our local hospital started the “healthy choices” nonsense with their vending machines a few years back. High local indigenous population, sales tanked, not-healthy choices returned.

  28. Up The Workers!

    Sound tantamount to saying:

    “Those who experiment with vicarious stupidity, end up as card-carrying Labor(sic) Party voters and members.”

  29. Up The Workers!

    To Arky at 7.19am,

    Who said:
    “Almost 80% of students have never smoked?
    Gay”

    I gather that the 80% of students you refer to, were not only gay, but were likely no more than 5 years old.

  30. Dot

    Think Opiates , nicotine, alcohol and eventually they’ll come full circle to caffeine. But then would you unban , say, Thalidomide?

    Yes.

    It can be combined with other off the shelf drugs to make anti cancer drugs more effective.

    The regulatory process failed because the molecule self racemises in the human body. They knew one isomer was bad for you.

  31. Pingback: Vaping Digest 4th December – vapers.org.uk

  32. Common sense should be enough to realize how inherently stupid this “Gateway” myth is. Just read a few of the several thousand empirical reports (testimonials aka “anecdotes”) on the CASAA site.

    You’ll find one trait common to most reports: Once a vaper has found the right combinations of device, flavor, and nicotine, there is no way they would voluntarily consider smoking again. No fear of relapse. Simply because vaping this way is much more enjoyable.

    What I wrote years ago is still true:
    Gate? No Way!

    And real science keeps confirming it.

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