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An anatomy of knowledge issues. Ric Sims Integrating ToK across the Diploma Curriculum Nairobi October 2011 . Terror. Hope (?). Result. Headline?. Is the tendency to smoke inherited?. If parents are smokers does this increase the likelihood that the children become smokers?. - PowerPoint PPT Presentation
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An anatomy of knowledge issues
Ric SimsIntegrating ToK across the Diploma
CurriculumNairobi October 2011
TerrorC-vitamin deficiency could lead to brain damage• (UNT – 2009)
Warning for acryl amide in coffee• (DN – 2002)
Hope (?)Coffee cures almost everything.• (The independent – 2009)
Diet control prolongs life• (Aftonbladet – 2009)
ResultMedia’s diet advice affects Swede’s food habits.•(Expressen – 2008)
Headline?Smoking is an inherited habit – if your parents smoked you are twice as likely to smoke yourself• (Sims weekly 2010)
Is the tendency to smoke inherited?If parents are smokers does this increase the
likelihood that the children become smokers?
Knowledge issues - observationLanguage: how exactly do we define
’smoker’? Once smoked, always smoked, sometimes smoked, 10 a day, 20 a day, 40 a day, only in the evenings? (this is more properly about concepts). Is it sufficient for the definition that just one parent smoked?
How do we extract information from the (messy) real world? Questionnaire? Who do we question (parents or children)? Reliability issues, wording of questionnaire (and so on)
Knowledge issues 2 - representationParents/children
smokers Non-smokers total
smokers 30 70 100Non-smokers 40 360 400total 70 430 500
Knowledge issues of manipulationIf parents smoking habits did not make a
difference we would expect that the proportion of smokers would be the same in both groups (those with smoking parents and those without)
(subtlety here: we assume an hypothesis of no effect and try to disprove it – cf. Popper and falsification)
This proportion is 70/430 = 16.3%
Expected distributionParent/children
smokers Non-smokers total
smokers 16 84 100Non-smokers 65 335 400total 81 419 500
Parents/children
smokers Non-smokers total
smokers 30 70 100Non-smokers 40 360 400total 70 430 500
Actual distribution
Model: Chi squaredGiven some basic technical assumptions
about the base population what is the probability that the observed distribution was achieved by chance?
First we decide on a significance levelWe calculate:
chi2 = sum of (observed – expected)**2/expected
In this case let us choose 5% significance level (i.e. We shall accept results which could be arrived at randomly from a uniform distribution with probability of 5% or less)
Chi squaredChi2 = 21. 3 for our resultsFrom the table our results
are highly significantthey are even significant at 0.1%meaning that our observed distribution is highly unlikely to come from aneven distribution randomly:i.e. There is a real effecthere
Knowledge issues: interpretationThe mathematical model tells us that there
the results are highly correlated (there is a strong correlation between the smoking behaviour of parents and that of their children)
But we need to do further work to establish causation
We would need to posit a mechanism – a piece of theory that uses general principles couched in psychological concepts to explain how one set of behaviours could cause the other
Models
Find a knowledge issue prompted by the following:The Federal Trade Commission has said that
advertisers and celebrities who endorse their products are liable for any untruthful statements they make regarding the effectiveness of their products – this includes statements they make on blogs and on social networking sites such as Twitter, Facebook and Myspace. (Financial Times 6 Oct 2009)