Alexander Tabarrok Based on Adam Glynn Does Oil

Alexander Tabarrok (Based on Adam Glynn, Does Oil Cause Civil War Because it Causes State Weakness? ) Mechanism-Specific Manski Bounds

Graphical Model for Mechanism State Weakness Oil Civil War

Oil on Civil War # of Obs Oil War Counter. Factuals War(No Oil) Potential Causal Effects War(Oil)-War(No Oil) 16 1 0 {0, 1} {0, -1} 3 1 1 {0, 1} {1, 0} Average Effect Bounds High bound: Suppose that in every case of oil and no war there would not have been a war without oil and that in every case of oil and war there would not have been a war without oil. 16/19*0+3/19*1=3/19. Low bound: Suppose that in every case of oil and no war there would have been a war without the oil and in every case of oil with war there would have been a war without oil. 16/19*-1+3/19*0=-16/19. Bounds on oil creates war {-16/19, 3/19}, i. e. data is compatible with oil having a big reduction in war or with a small positive effect on war.

Oil on State Weakness # of Obs Oil SW Counter. Factuals SW(No Oil) Potential Causal Effects SW(Oil)-SW(No Oil) 19 1 0 {0, 1} {0, -1} 9 1 1 {0, 1} {1, 0} Average Effect Bounds High bound: Suppose that in every case of oil and no SW there would have been no SW without oil and that in every case of SW with oil there would have been no SW without oil. 19/28*0+9/28*1=9/28. Low bound: Suppose that in every case of oil and no SW there would have been SW without the oil and in every case of SW with oil there would have been SW without oil. 19/28*-1+9/28*0=-19/28. Bounds on oil creates state weakness {-19/28, 9/28}, i. e. data is compatible with oil having a big reduction in SW or a fairly big positive effect on SW.

Oil on Civil War Through State Weakness # of Oil Obs SW War Potential Causal Effects SW(Oil)-SW(No Oil) War(SW)-War(No SW) Product: Oil causes War through SW 16 1 0 0 {0, -1} 3 1 0 1 {0, -1} {0, 1} 9 1 1 0 {0, 1} {0, -1} 0 1 1 1 {0, 1} Average Effect Bounds High bound: 3/28*1+0/28*1+16/28*0+9/28*0=3/28 {0, 1} Low bound: 16/28*-1+3/28*0+9/28*-1+0/28*0=-25/28 Bounds on oil creates war through state weakness {-25/28, 3/28}, i. e. data is compatible with oil having a big reduction in War through SW or a small positive effect on War through SW.

Monotone treatment assumption: Assume that SW cannot reduce chances of Oil on Civil War Through State war. Weakness # of Oil Obs SW War Potential Causal Effects SW(Oil)-SW(No Oil) Potential Causal Effects War(SW)-War(No SW) Product: Oil causes War through SW 16 1 0 0 {0, -1} 3 1 0 1 {0, -1}0} {0, 1}0} 9 1 1 0 {0, 1} {0, -1}0} 0 1 1 1 {0, 1} Note something a little odd. Where is potential evidence coming from that Oil causes War through SW? Consider the row with 3 obs. We have Oil, no SW, and war. Would seem to rule against hypothesis. But notice that the bounds are from Oil reduces SW & SW reduces War thus if Oil then SW and thus War (-1*-1=1). See also row with 9 obs. � Oil could reduce or increase SW but suppose that we rule out that SW can decrease civil war. What then? � High bound: 0 � Low bound: 16/28*-1=-16/28 Bounds {-16/28, 0}. Thus Oil is not compatible with causing war through SW. �