Andrew Bolt vs percentages

Andrew Bolt may have the worst case of confirmation bias ever seen. To Bolt, whether something is true or not has nothing to do with its accuracy and everything to do with whether it suits him or not. Here in its entirety,

If the evidence were so strong, there’d be no need for such untruths

Dennis Ambler checks the statistics behind recently claims that 97 per cent of climate scientists believe man is heating the planet and finds evidence of some exaggeration:

However a headline of “0.73% of climate scientists think that humans are affecting the climate” doesn’t quite have the same ring as 97% does it?

Er, no.

He’s referring to Doran and Zimmerman’s survey of 3146 Earth Scientists. The graph below shows their results for this question:

Do you think human activity is a significant contributing factor in changing mean global temperatures?

i-53bd554612884f2d57067c1845ddfc23-DoranAndZimmerman2009.png

So what’s Ambler’s argument that proves that the 97% is really 0.73%?


The response to this question was 75 specialists out of 77, so here we have our massive 97%.

It is disingenuous to now use the “climate scientists” as a new population sample size. The response figure of 3,146 is the figure against which the 75 out of 77 should be compared and in this case we get not 97% but just 2.38%.

Err, no. Percentages don’t work that way. If you want to know the percentage of the 3146 Earth scientists that said “yes”, you have to divide the number of them that said yes (about 2580) by the sample size (3146) to get 82%.

This is something that students are supposed to learn in primary school. I would imagine that even Andrew Bolt could do primary school maths, so the reason that he didn’t notice that
Ambler was wrong was because of his confirmation bias.

Ambler gets the number down further with this:

The original number contacted was 10,157 and of those, 69% decided they didn’t want any part of it, but they were the original target population. When the figure of 75 believers is set against that number, we get a mere 0.73% of the scientists they contacted who agreed with their loaded questions.

We don’t know how the non-responders would have answered, but it is clearly wrong to assume, as Ambler does and Bolt blindly agrees, that they would all have answered “no”. The most reasonable assumption is that they their answers would be similar to that of the responders and 82% of Earth scientists would say “yes”. And this does not contradict the 97% figure, which was for active climate scientists.

The sad thing is that I don’t think Bolt is lying — why write something so easily shown to be untrue? Bolt’s severe confirmation bias mean that he is a less reliable source of information than someone who lies strategically.

Comments

  1. #1 zoot
    January 13, 2011

    Once saw the name Mike Hunt-Hertz listed as waiting for a CES interview.

  2. #2 Shinsko
    February 14, 2011

    Bolt has just posted a [re-run](http://blogs.news.com.au/heraldsun/andrewbolt/index.php/heraldsun/comments/how_to_make_97_per_cent_of_climate_experts_agree/) on this story.

    Apparently,

    >The survey results must have deeply disappointed the researchers — in the end, they chose to highlight the views of a subgroup of just 77 scientists, 75 of whom thought humans contributed to climate change. The ratio 75/77 produces the 97% figure that pundits now tout.

  3. #3 Mr. Papaya
    February 14, 2011

    I have no interest in casting pearls before swine, so if you want a simple dissection of the untruths spewed forth by your leading authority ‘computer scientist’, visit the link generously provided by Shinsko.

  4. #4 jakerman
    February 15, 2011

    >*The survey results must have deeply disappointed the researchers — in the end, they chose to highlight the views of a subgroup of just 77 scientists, 75 of whom thought humans contributed to climate change. The ratio 75/77 produces the 97% figure that pundits now tout.*

    Bolt is a moron or A-grade distorter. The 77 are the full complement of respondents that are activly publishing climate scientist. Re *”highlighting their veiws”*; The two things that distinguish them from the other catgories of respondents is a) their level of competence in the material, and b) their higher level of Agreement with the IPCC proposition.

    The resutls show clearly that more competent on is in the field the more likey ones views aling with thoses statede in the IPCC 4th Assessment report.

  5. #5 FrankD
    February 15, 2011

    But in Blotland “the more competent in the field…” morphs into “the further one’s snout is into the billion dollar trough…”

    “I don’t need your percentages, Miss Prissy. I’ve got my ideology to keep me warm…”

    (with apologies to Foghorn Leghorn, of whom Blot always reminds me…)

  6. #6 Wow
    February 15, 2011

    > I have no interest in casting pearls before swine,

    Or, in other words:

    Oink.

    How’s that well known scientist Dr Doom doing for your Oregon Petition?

  7. #7 Will S
    July 27, 2011

    Bolt will go on a respectable TV show and say something like “of course climate is changing, and perhaps man is contributing, but the question is just whether it’s worth taking action”. Then the next morning he will post a dodgy graph from some denalist blog claiming temperatures aren’t changing at all, and his mouth-breathing readers will post their usual garbage.

    Someone needs to demand that he (and all other skeptics) actually propose their own coherent, consistent explanation of what is going on. Take all the data and provide an explanation (theory) of what is happening that accounts for all observations better than what climate scientists currently say. He doesn’t have any such position.

  8. #8 Bernard J.
    July 27, 2011

    [Will S](http://scienceblogs.com/deltoid/2011/01/andrew_bolt_vs_percentages.php#comment-4601770).

    In the same vein as Bolt’s malleable pseudoscience, you might be entertained to know that Jennifer Marohasy is currently regurgitating Steven Goddard’s suggestion which essentially posits that there is no greenhouse effect, because the extra CO2 in the atmosphere is not altering how the stars twinkle.

    Her denialist minions are having a a field day slavering and gnawing on that bone. Shame for them that it’s a pretend one…

  9. #9 Lotharsson
    July 27, 2011

    > …Steven Goddard’s suggestion which essentially posits that there is no greenhouse effect, because the extra CO2 in the atmosphere is not altering how the stars twinkle.

    Good grief! Someone is mining a rich vein of Teh Stupid.