chicken little hypotheses null hypothesis (h 0 ): chicken little is wrong and everything is normal....
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Chicken Little hypotheses
• Null Hypothesis (H0):
Chicken Little is wrong and everything is normal.
• Alternative Hypothesis (Ha):
Chicken Little is correct and the sky is falling!
Decision:
CorrectType 1 Error
“False Positive”
Type 2 Error
“False Negative”
Null is False
Null is True
Reality:
Correct
Reject Null
Fail to Reject Null
What type of error did the birds make when they listened to Chicken Little?
Decision:
CorrectType 1 Error
“False Positive”
Type 2 Error
“False Negative”
Null is False
Null is True
Reality:
Correct
Reject Null
Fail to Reject Null
What type of error did the birds make when they listened to Chicken Little?
Cassandra
• Granted the power of prophecy by Apollo.
• Cursed so that no one would believe her
• Prophecy of the Trojan Horse and the Fall of Troy
Cassandra hypotheses• Null Hypothesis (H0):
Cassandra is wrong and the Trojans are winning the war.
• Alternative Hypothesis (Ha):
Cassandra is correct and a Greek ambush is imminent!
Decision:
CorrectType 1 Error
“False Positive”
Type 2 Error
“False Negative”
Null is False
Null is True
Reality:
Correct
Reject Null
Fail to Reject Null
What type of error did the Trojans make when they didn’t listen to Cassandra?
Decision:
CorrectType 1 Error
“False Positive”
Type 2 Error
“False Negative”
Null is False
Null is True
Reality:
Correct
Reject Null
Fail to Reject Null
What type of error did the Trojans make when they didn’t listen to Cassandra?
Thomas Malthus (~1800)
• Economist who studied populations.
• Exponential population growth, linear food production (boom and bust)
• Positive checks: famine, disease, and war (death)
• Preventative checks: Birth control, abortion, and older ages of marriage
Malthusian Growth Model
Has there been a “Malthusian
catastrophe”?
Ester Boserup• Mid to late 1900s
• “Boserupian Theory”
• Developments or inventions cause jumps in the food supply to match the growing population
Time
Time
Consequences?
Malthusian hypotheses
• Null Hypothesis (H0):
Malthus is wrong and catastrophe is not imminent.
• Alternative Hypothesis (Ha):
Malthus is correct and catastrophe IS imminent
Decision:
Correct(Malthus is right, and we agreed with him).
Type 1 Error(Malthus is wrong and we agreed with him). Chicken Little
Type 2 Error(Malthus is right and we disagreed with him). Cassandra
Null is False
Null is True
Reality:
Correct(Malthus is wrong and we disagreed with him).
Reject Null
Fail to Reject Null
What would be the consequences of a Type 2 Error?of a Type 1 Error?
Malthus
Decision:
Correct(Malthus is right, and we agreed with him).
Type 1 Error(Malthus is wrong and we agreed with him). Chicken Little
Type 2 Error(Malthus is right and we disagreed with him). Cassandra
Null is False
Null is True
Reality:
Correct(Malthus is wrong and we disagreed with him).
Reject Null
Fail to Reject Null
What would be the consequences of a Type 2 Error?of a Type 1 Error?
Malthus
Julian Simon• Economist
• Consequences of Type 1 error: slowing of economic growth
• Human ingenuity the scarcest resource
• Growth and development are the answer to our problems
Riskiness of Errors• Chicken Little?• Cassandra?• Malthus? (Overpopulation?)
• Climate Change?
Climate hypotheses• Null Hypothesis (H0):
Climate Scientists are wrong and catastrophe is not imminent.
• Alternative Hypothesis (Ha):
Climate Scientists are correct and catastrophe IS imminent
Decision:
Null is False
Null is True
Reality:
Reject Null
Fail to Reject Null
Climate Scientists are right and we agree with them. Action.
Type 1 Error (Chicken Little)“False Positive”
Consequences?Risky?
Type 2 Error(Cassandra)“False Negative”
Consequences? Risky?
Climate Scientists are wrong and we disagree with them. Inaction.