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- The Lucas and Stokey (1983) plan is easy to calculate because it is essentially static. This is due to its history-independence property for variables like consumption, labor and the tax rate, xt(gt , 0, 0) = x(gt, 0, 0).13 The expansion is focused on the calculation of the partial derivatives xi t(0), i = R, A, which are random variables in most cases. Substantial simplification comes from the fact that, without doubts about the model, the conditional and unconditional likelihood ratios become unity, mâ t (0) = nâ t (0) = Mâ t (0) = Nâ t (0) = Ît(0) = 1. Furthermore, there is no room for price manipulation through continuation utilities, so Ë Î¾t(0) = 0, and the governmentâs and householdâs utility coincide, Wt(0) = Vt(0), since both the government and the household share the same reference model.
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- X i=0 rx,i + Ë Î¾iux,i Îi . (B.26) The interesting feature of the âNKâ case is that the sign of the multiplier ÏÌt depends now on the details of the application.11 Therefore, the amplification or mitigation of beliefs depends both on the sign of the multipliers and on the correlation of x with shocks. Signing the derivatives rx and ux may not be necessarily straightforward. For example, if we had a New-Keynesian model, rx can be positive or negative depending on where inflation is relative to the target and this may be changing over time depending on the history of shocks stâ1 .12 10 The formula for the optimal tax rate in proposition 1 is derived effectively by expressing (B.24) in terms of the policy instrument for the case of r = u. 11 Note that depending on the application, the return functions can be the same or different. For example, in Benigno and Paciello (2014) the firm is owned by the household, leading to a setup where r = u is natural.
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