I’m having some problems in computing the steady state under optimal policy with ramsey policy. Can you help me, please?
My problem is the following:
1. I have derived by hand the optimal values for the steady state of all endogenous variables (55 variables) given the optimal value of the policy instruments (6 instruments). I have entered these values in the “steady state model” block.
2. I have provided the optimal values of the instruments in the “initval” block. Actually, these values are the steady state values.
3. I have declared the name of the endogenous variables that are the instruments within the ramsey policy command (instruments=()).
4. I ran the .mod file with dynare unstable version: 13-Jun-2016. I’m using the unstable version because I read in the forum that the stable version 4.4.3. has a bug related to auxiliary variables when using instruments. The results I obtain are:
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evaluate_steady_state: The steady state for the Ramsey problem could not be computed.
evaluate_steady_state: The steady state computation stopped with the following instrument values::
tauIVA_sec2 0.100000
tauIVA_sec3 0.100000
tauK_dec2 0.300000
tauK_dec3 0.300000
tauL_dec2 0.250000
tauL_dec3 0.300000
evaluate_steady_state: The following equations have non-zero residuals:
Auxiliary Ramsey equation number 1: -0.032906
Auxiliary Ramsey equation number 2: -0.033535
Auxiliary Ramsey equation number 3: 0.017759
Auxiliary Ramsey equation number 4: 0.017131
Auxiliary Ramsey equation number 5: -0.015146
Auxiliary Ramsey equation number 6: -0.016404
Auxiliary Ramsey equation number 7: 0.012183
Auxiliary Ramsey equation number 8: 0.003006
Auxiliary Ramsey equation number 9: 0.003866
Auxiliary Ramsey equation number 10: 0.000507
Auxiliary Ramsey equation number 11: 0.008317
Auxiliary Ramsey equation number 12: 0.002499
Auxiliary Ramsey equation number 13: 0.074317
Auxiliary Ramsey equation number 14: -0.003846
Auxiliary Ramsey equation number 15: -0.017203
Auxiliary Ramsey equation number 16: -0.003085
Auxiliary Ramsey equation number 17: -0.013428
Auxiliary Ramsey equation number 18: 0.000196
Auxiliary Ramsey equation number 19: 0.000070
Auxiliary Ramsey equation number 20: -0.000171
Auxiliary Ramsey equation number 21: -0.000172
Auxiliary Ramsey equation number 22: -0.006400
Auxiliary Ramsey equation number 23: 0.001580
Auxiliary Ramsey equation number 24: -0.025349
Auxiliary Ramsey equation number 25: 0.039403
Auxiliary Ramsey equation number 26: -0.001604
Auxiliary Ramsey equation number 27: -0.001282
Auxiliary Ramsey equation number 28: 0.002554
Auxiliary Ramsey equation number 29: 0.015522
Auxiliary Ramsey equation number 30: 0.002554
Auxiliary Ramsey equation number 31: -0.009827
Auxiliary Ramsey equation number 32: -0.003846
Auxiliary Ramsey equation number 33: 0.017102
Auxiliary Ramsey equation number 34: 0.044655
Auxiliary Ramsey equation number 35: 0.038571
Auxiliary Ramsey equation number 36: 0.044655
Auxiliary Ramsey equation number 37: 0.038762
Auxiliary Ramsey equation number 38: 0.039403
Auxiliary Ramsey equation number 39: 0.039403
Auxiliary Ramsey equation number 40: 0.005252
Auxiliary Ramsey equation number 41: -0.000832
Auxiliary Ramsey equation number 42: -0.003386
Auxiliary Ramsey equation number 43: 0.014827
Auxiliary Ramsey equation number 44: 0.020721
Auxiliary Ramsey equation number 45: 0.074847
Auxiliary Ramsey equation number 46: 0.080740
Auxiliary Ramsey equation number 47: 0.003053
Auxiliary Ramsey equation number 48: 0.000400
Auxiliary Ramsey equation number 49: 0.003121
Auxiliary Ramsey equation number 50: 0.000938
Auxiliary Ramsey equation number 51: 0.074318
Auxiliary Ramsey equation number 52: 0.074318
Auxiliary Ramsey equation number 53: 0.074313
Auxiliary Ramsey equation number 54: 0.074317
Auxiliary Ramsey equation number 55: -0.003386
Equation number 1: 0.049710
Equation number 2: 0.041753
Equation number 3: -0.028472
Equation number 4: -0.028475
Equation number 5: -0.039529
Equation number 6: -0.086000
HOWEVER, when I use dynare version 4.4.3 and I (i) set the optimal values for the steady state of all endogenous variables (including the 6 intruments) in the “initval” block instead of setting the optimal values in the “steady state model” block, and (ii) deleting the option “instruments” within the ramsey policy command, Dynare solves the model and reaches the steady state. Nevertheless, the “resid” command reports the following:
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Residuals of the static equations:
Equation number 1 : -0.03276
Equation number 2 : -0.033378
Equation number 3 : 0.017772
Equation number 4 : 0.017153
Equation number 5 : -0.014988
Equation number 6 : -0.016224
Equation number 7 : 0.011865
Equation number 8 : 0.002914
Equation number 9 : 0.0034553
Equation number 10 : 0.00036206
Equation number 11 : 0.0084097
Equation number 12 : 0.0025519
Equation number 13 : 0.0743
Equation number 14 : -0.0040414
Equation number 15 : -0.01709
Equation number 16 : -0.0032417
Equation number 17 : -0.013339
Equation number 18 : 0.0001925
Equation number 19 : 6.8891e-05
Equation number 20 : -0.00016844
Equation number 21 : -0.00016878
Equation number 22 : -0.0064069
Equation number 23 : 0.0015816
Equation number 24 : -0.025375
Equation number 25 : 0.039392
Equation number 26 : -0.0016012
Equation number 27 : -0.0012908
Equation number 28 : 0.0023655
Equation number 29 : 0.015537
Equation number 30 : 0.0023655
Equation number 31 : -0.0098379
Equation number 32 : -0.0040414
Equation number 33 : 0.017119
Equation number 34 : 0.044649
Equation number 35 : 0.038559
Equation number 36 : 0.044649
Equation number 37 : 0.03875
Equation number 38 : 0.039392
Equation number 39 : 0.039392
Equation number 40 : 0.0052569
Equation number 41 : -0.00083322
Equation number 42 : -0.0033918
Equation number 43 : 0.014724
Equation number 44 : 0.020623
Equation number 45 : 0.074932
Equation number 46 : 0.080831
Equation number 47 : 0.0054035
Equation number 48 : 0.00056621
Equation number 49 : 0.0062487
Equation number 50 : 0.0018961
Equation number 51 : 0.0743
Equation number 52 : 0.0743
Equation number 53 : 0.074295
Equation number 54 : 0.074299
Equation number 55 : -0.0033918
Equation number 56 : 0.049704
Equation number 57 : 0.041739
Equation number 58 : -0.028463
Equation number 59 : -0.028466
Equation number 60 : -0.039472
Equation number 61 : -0.08606
I double checked the file “ed3_static.m” after running the 4.4.3 version and I founded the following similarities between the “resid” reports of the unstable and stable dynare versions:
(i) residual(1) to residual(55) equations correspond to the residuals of the Lagrange multipliers of my 55 endogenous variables (equivalent to the “Auxiliary Ramsey equation number 1 to 55”, in the resid report of the unstable version).
(ii) residual(56) to residual(61) equations are the Lagrange multipliers of my instruments (equivalent to “Equation number 1 to 6”, in the resid report of the unstable version).
(iii) residual(62) to residual(116) are the residuals of my 55 model equations. These residuals are zero according to the “ans” report generated in the matlab workspace. Consequently, the optimal values I derived for the steady state of all the endogenous variables (55 variables), given the value of the 6 policy instruments, are correct!. Moreover, when I disable the ramsey policy command and solve my model with the steady command (in both stable and unstable versions) I obtain the optimal steady state, residuals of the static equations are zero, and the rank condition is verified. It is, my initial values are right.
(iv) residual(117) to residual(124) are the residuals of the 8 auxiliary equations (all of them zero according to the “ans” report generated in the matlab workspace) generated by dynare. These equations are included in the “ed3_set_auxiliary_variables.m”
IT’S MY IMPRESSION AND I COULD BE WRONG, THAT THE dynare version 4.4.3 IGNORES THE RESULTS OF THE RESIDUAL EQUATIONS OF THE LAGRANGE MULTIPLIERS, AND ONLY TAKES INTO CONSIDERATION THAT THE RESIDUALS OF ALL ENDOGENOUS VARIABLES ARE ZERO FOR PROVIDING A SOLUTION. IT SEEMS THAT THE OPPOSITE HAPPENS FOR THE UNSTABLE VERSION…
QUESTIONS/HELP:
1. Is there a way of ignoring the residuals of the lagrange multipliers when using the unstable version?, or
2. Is there a way in which dynare can compute/solve with more precision the optimal values of the lagrange multipliers such that their residual equations be zero?
I know that probably one solution could be to use the stable version, set the optimal values of my entire endogenous variables and instruments in the initialval block, set the ramsey policy command without instruments, let that Dynare solves the problem, and don’t pay attention to the residuals of the auxiliary variables… However, I’m going to run a large model and I prefer to reduce computing time when setting the optimal values in the steady state model block, and let Dynare solve the problem with only as many unkowns as there are instruments, rather than solving the model with as many unknowns as there are endogenous variables in the case of setting the optimal values in the initialval block…
Thanks in advance,
Eduardo