3. Chicken Little hypotheses Null Hypothesis (H 0 ): Chicken Little is wrong and everything is normal. Alternative Hypothesis (H a ): Chicken Little is correct and the sky is falling!

4. Decision: Correct Type 1 Error “False Positive” Type 2 Error “False Negative” Null is FalseNull is True Reality: Correct Reject Null Fail to Reject Null What type of error did the birds make when they listened to Chicken Little?

5. Decision: Correct Type 1 Error “False Positive” Type 2 Error “False Negative” Null is FalseNull is True Reality: Correct Reject Null Fail to Reject Null What type of error did the birds make when they listened to Chicken Little?

6. 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

7. Cassandra hypotheses Null Hypothesis (H 0 ): Cassandra is wrong and the Trojans are winning the war. Alternative Hypothesis (H a ): Cassandra is correct and a Greek ambush is imminent!

8. Decision: Correct Type 1 Error “False Positive” Type 2 Error “False Negative” Null is FalseNull 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?

9. Decision: Correct Type 1 Error “False Positive” Type 2 Error “False Negative” Null is FalseNull 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?

10. 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

11. Malthusian Growth Model

12. Has there been a “Malthusian catastrophe”?

13. Ester Boserup Mid to late 1900s “Boserupian Theory” Developments or inventions cause jumps in the food supply to match the growing population

14. Time

16. Consequences?

17. Malthusian hypotheses Null Hypothesis (H 0 ): Malthus is wrong and catastrophe is not imminent. Alternative Hypothesis (H a ): Malthus is correct and catastrophe IS imminent

18. 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 FalseNull 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

19. 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 FalseNull 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

20. 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

21. Riskiness of Errors Chicken Little? Cassandra? Malthus? (Overpopulation?) Climate Change?

22. Climate hypotheses Null Hypothesis (H 0 ): Climate Scientists are wrong and catastrophe is not imminent. Alternative Hypothesis (H a ): Climate Scientists are correct and catastrophe IS imminent

23. Decision: Null is FalseNull 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.