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Spurious Relationship
A correlation between two variables that have no causal relationship; both variables are caused by another variable
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Scatterplot illustration of a spurious relationship
All Fires Fire Damage Only small fires Fire Damage Only large fires Fire trucks Fire Damage Fire trucks Fire trucks
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Scatterplot illustration of a spurious relationship
All months Babies Only fall and winter months Babies Only spring and summer months Storks Babies Storks Storks
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Example of correlation
Reconciliation Truth
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Solution Logic: deep concern about the logic of the causal mechanism
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Does truth lead to reconciliation?
I find it difficult to understand the customs and ways of [the opposite racial group]. It is hard to imagine ever being friends with a [the opposite racial group]. More than most groups, [the opposite racial group] are likely to engage in crime. [The opposite racial group] are untrustworthy. [The opposite racial group] are selfish, and only look after the interests of their group. I feel uncomfortable when I am around a group of [the opposite racial group]. I often don't believe what [the opposite racial group] say to me. South Africa would be a better place if there were no [the opposite racial group] in the country. I could never imagine being part of a political party made up mainly of [the opposite racial group].
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Does truth lead to reconciliation?
Apartheid was a crime against humanity. (True). There were certainly some abuses under the old apartheid system, but the ideas behind apartheid were basically good ones. (False) The struggle to preserve apartheid was just. (False) Both those struggling for and those struggling against the old apartheid system did unforgivable things to people. (True) The abuses under apartheid were largely committed by a few evil individuals, not by the state institutions themselves. (False)
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An illustration with a causal model
A and B are spuriously correlated if: A and B are NOT spuriously correlated if: Z Z A B A B
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A test of whether A and B are spurious
Look at the relationship between A and B, controlling for Z This means, that for all values of Z, you should look at the relationship between A and B.
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Scatterplot illustration of a spurious relationship
All South Africans Reconciliation Reconciliation Only racists Truth Only non- racists Reconciliation Truth Truth
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Explaining Venn Diagrams
Variance Reconciliation
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Explaining Venn Diagrams
Variance Truth
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Explaining Venn Diagrams
Variance Racism
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Plot showing positive covariance
Mean urban % Mean female literacy
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Plot showing negative covariance
Mean calorie intake Mean infant mortality
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Plot showing no covariance
Mean GDP Mean crop production
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Venn diagram showing truth is only spuriously related to reconciliation
Racism Reconciliation
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Scatterplot illustration of a spurious relationship
All South Africans Reconciliation Reconciliation Only racists Truth Only non- racists Reconciliation Truth Truth
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Scatterplot illustration of a relationship that is {not necessarily} spurious
All South Africans Reconciliation Reconciliation Only racists Truth Only non- racists Reconciliation Truth Truth
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Venn diagram showing truth has an independent impact on reconciliation
Racism Reconciliation
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