forked from llorracc/SolvingMicroDSOPs
-
Notifications
You must be signed in to change notification settings - Fork 2
/
Copy pathSolvingMicroDSOPs-Slides.tex
720 lines (528 loc) · 20.3 KB
/
SolvingMicroDSOPs-Slides.tex
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
\input{./.econtexRoot}\documentclass{beamer}
\usepackage{import}
\usepackage{ulem}
\usepackage[Overlays]{optional}
\usepackage{ifthen}
\usepackage{\econtexShortcuts}
%\usepackage{bbm}
\providecommand{\Ex}{\ensuremath{\mathbb{E}}} % Expectations operator defined in econtex.cls
\usepackage{\LaTeXInputs/SolvingMicroDSOPs}
\usepackage{econark}
% if this is uncommented, bullets are shown step by step; comment out to make printable version
\beamerdefaultoverlayspecification{<+->}
% MPCMatch
\provideboolean{MPCMatchVersion}
\setboolean{MPCMatchVersion}{true}
\setboolean{MPCMatchVersion}{false}
\newcommand{\MPCMatch}{\ifthenelse{\boolean{MPCMatchVersion}}}
\newboolean{DiscountSubOn}
\setboolean{DiscountSubOn}{false}
\providecommand{\TimeFactor}{\Discount}
\ifthenelse{\boolean{DiscountSubOn}}{\Discount_{t+1}}{}
\newcommand{\ifTimeSubT}{}
\ifthenelse{\boolean{DiscountSubOn}}{\renewcommand{\ifTimeSubT}{_{T}}}{}
\newcommand{\ifTimeSubNext}{}
\ifthenelse{\boolean{DiscountSubOn}}{\renewcommand{\ifTimeSubNext}{_{t+1}}}{}
\newboolean{RfreeSubOn}
\setboolean{RfreeSubOn}{false}
\providecommand{\R}{\Rfree}
\ifthenelse{\boolean{RfreeSubOn}}{\Rfree_{t+1}}{}
\usepackage{ifthen}
\newboolean{WithOverlays}
\setboolean{WithOverlays}{true}
\usepackage{optional}
\opt{NoOverlays}{\setboolean{WithOverlays}{false}\beamerdefaultoverlayspecification{}}
\usepackage{moreverb}
\usepackage{cancel}
\usepackage{econtexShortcuts}
\usepackage{wasysym}
%\usepackage{dcolumn}
% \usepackage[notocbib]{apacite}
%\renewcommand{\frametitle}{\textbf\frametitle}
% Jirka's definitions
\usepackage[authoryear]{natbib}
\definecolor{jirkasred}{rgb}{0.9,0,0}
\newcommand{\jemph}[1]{{\color{jirkasred}#1}}
\def\newblock{\hskip .11em plus .33em minus .07em}
\mode<presentation>
{
\usetheme{default}
% or ...
\setbeamercovered{transparent}
}
% if this is on, bullets are shown step by step
% \beamerdefaultoverlayspecification{<+->}
%\setbeamertemplate{navigation symbols}{} % Take away navigation symbols
\usetheme{Frankfurt}
%_____________ Opening slide _______________________
\begin{document}
%\begin{verbatimwrite}{./SolvingMicroDSOPs-Slides-body.tex}
\title[SolvingMicroDSOPs]{\textbf{Structural Estimation of Dynamic Stochastic\\ Optimizing Models of Intertemporal Choice \\ \LARGE{For Dummies!}}}
\author[Carroll]{Christopher Carroll\inst{1}}
\institute{
\inst{1} Johns Hopkins University and NBER\\ \texttt{[email protected]} \and
}
\date{June 2012 \\ {\tiny \url{http://www.econ2.jhu.edu/people/ccarroll/SolvingMicroDSOPs-Slides.pdf}}
}
\begin{frame}[plain]
\titlepage
\end{frame}
\section{Introduction}
\begin{frame}
\begin{itemize}
\item Efficient Solution Methods for Canonical $C$ problem
\begin{itemize}
\item CRRA utility
\item Plausible (microeconomically calibrated) uncertainty
\item Life cycle or infinite horizon
\end{itemize}
\item How To Add a Second Choice Variable
\item Method of Simulated Moments Estimation of Parameters
\end{itemize}
\end{frame}
\section{The Problem}
\begin{frame}[label=MaxProb]
\frametitle{\large\textbf{The Basic Problem at Date $t$}}
\input{./Equations/MaxProb.tex}
\begin{equation}\begin{gathered}\begin{aligned}
{\yLev}_{t} & = {\pLev}_{t}\TranShkEmp_{t}
\end{aligned}\end{gathered}\end{equation}
\input{./Equations/ExogVars.tex}
\end{frame}
\begin{frame}[label=vrecurse]
\frametitle{\large\textbf{Bellman Equation}}
\input{./Equations/vrecurse.tex}
\begin{equation*}\begin{gathered}\begin{aligned}
\mLev & - & \text{ `market resources' (net worth plus current income)}
\\ \pLev & - & \text{ permanent labor income }
\end{aligned}\end{gathered}\end{equation*}
\end{frame}
\section{Tricks}
\subsection{Normalization}
\begin{frame}[label=Normalize]
\frametitle{\large\textbf{Trick: Normalize the Problem}}
\input{./Equations/vNormed.tex}
where nonbold variables are bold ones normalized by $\pLev$:
\begin{equation}\begin{gathered}\begin{aligned}
\mRat_{t} & = \mLev_{t}/\pLev_{t}
\end{aligned}\end{gathered}\end{equation}
Yields $\cFunc_{t}(m)$ from which we can obtain
\begin{equation}\begin{gathered}\begin{aligned}
\cLev_{t}(\mLev_{t},\pLev_{t}) & = \cFunc_{t}(\mLev_{t}/\pLev_{t})\pLev_{t}
\end{aligned}\end{gathered}\end{equation}
\end{frame}
\begin{frame}[label=Normalize]
\frametitle{\large\textbf{When Doesn't Normalization Work?}}
\begin{itemize}
\item Non-CRRA utility
\item Non-Friedman (transitory/permanent) income process
\begin{itemize}
\item e.g., AR(1)
\item But micro evidence is consistent with Friedman
\end{itemize}
\end{itemize}
\end{frame}
\subsection{View Problem from End of Period}
\begin{frame}[label=Normalize]
\frametitle{Trick: View Everything from End of Period}
Define
\input{./Equations/vEndtdefn.tex}
so
\begin{equation}\begin{gathered}\begin{aligned}
\vFunc_{t}(\mRat_{t}) & = \max_{\cNrm_{t}}~~ \util(\cNrm_{t}) + \vEnd_{t}(\mRat_{t}-\cNrm_{t})
\end{aligned}\end{gathered}\end{equation}
with FOC
\input{./Equations/upEqbetaOp.tex}
and Envelope relation
\input{./Equations/Envelope.tex}
\end{frame}
\subsection{Discretization of Risks}
\begin{frame}[label=DiscretizeFig]
\frametitle{Trick: Discretize the Risks}
E.g.\ use an equiprobable 7-point distribution:\medskip\medskip
\includegraphics[width=4in]{./Figures/discreteApprox.pdf}
\end{frame}
\begin{frame}[label=DiscretizeEqn]
\frametitle{Trick: Discretize the Risks}
\begin{equation}\begin{gathered}\begin{aligned}
\vEnd_{t}^{\prime}({a}_{t}) & = \Discount \Rfree \PermGroFac_{t+1}^{-\CRRA} \left(\frac{1}{n}\right) \sum_{i=1}^{n} \util^{\prime}\left(\cFunc_{t+1}(\RNrm_{t+1} {a}_{t} + \TranShkEmp_{i})\right)
\end{aligned}\end{gathered}\end{equation}
%\input{./Equations/vDiscrete.tex}
\pause
So for any particular $\mRat_{T-1}$ the corresponding $\cNrm_{T-1}$ can be found
using the FOC:
\input{./Equations/upEqbetaOp.tex}
\end{frame}
\subsection{Interpolate a Consumption Rule}
\begin{frame}
\frametitle{Trick: Interpolate a Consumption Rule}
\begin{enumerate}
\item Define a grid of points $\vec{\mRat}$ (indexed $\mRat[i]$)
\item Use numerical rootfinder to solve
$\util^{\prime}(\cNrm) = \vEnd^{\prime}_{t}(\mRat[i]-\cNrm)$
\begin{itemize}
\item The $\cNrm$ that solves this becomes $\cNrm[i]$
\end{itemize}
\item Construct interpolating function $\grave{\cFunc}$ by linear interpolation
\begin{itemize}
\item `Connect-the-dots'
\end{itemize}
\end{enumerate}
\end{frame}
\begin{frame}[label=DiscretizeEqn]
\frametitle{Trick: Interpolate a Consumption Rule}
Example: $\vec{\mRat}_{T-1} = \{0.,1.,2.,3.,4.\}$ (solid is `correct' soln)
\includegraphics[width=4.0in]{./Figures/PlotcTm1Simple.pdf}
\end{frame}
\begin{frame}[label=vEndtSlow]
\frametitle{Problem: Numerical Rootfinding is {\it Slow}}
Numerical search for values of $\cNrm_{T-1}$ satisfying
$\util^{\prime}(\cNrm) = \vEnd^{\prime}_{t}(\mRat[i]-\cNrm)$ at, say,
6 gridpoints of $\vec{\mRat}_{T-1}$ may require hundreds or even thousands of
evaluations of
\begin{equation}\begin{gathered}\begin{aligned}
\vEnd^{\prime}_{T-1}(\overbrace{{m}_{T-1}-{\cNrm}_{T-1}}^{\aRat_{T-1}}) & = \Discount_{T} \PermGroFac_{T}^{1-\CRRA}\left(\frac{1}{n}\right)\sum_{i=1}^{n} \left( \RNrm_{T} {a}_{T-1} + \TranShkEmp_{i}\right)^{-\CRRA} \notag
\end{aligned}\end{gathered}\end{equation}
\end{frame}
\begin{comment}
\begin{frame}[label=vApprox]
\frametitle{Solution: Approximate $\vEnd$?}
\pause Given $\{\vec{\aRat}_{T-1},\vec{\vEnd}_{T-1}\}$, an approximate function $\grave{\vEnd}_{T-1}$
can be constructed by linear interpolation among the points:
\includegraphics[width=4in]{./Figures/PlotOTm1RawVsInt.pdf}
\end{frame}
\begin{frame}
\frametitle{Using $\grave{\vEnd}_{T-1}$ In Optimization}
\begin{equation*}\begin{gathered}\begin{aligned}
\vFunc_{t}(\mRat_{t}) & = \max_{\cNrm_{t}}~~ \util(\cNrm_{t}) + \grave{\vEnd}_{t}(\mRat_{t}-\cNrm_{t})
\end{aligned}\end{gathered}\end{equation*}
is {\it much} faster, but result is bad:
\begin{center}
\includegraphics[width=3in]{./Figures/PlotComparecTm1AB}
\end{center}
\end{frame}
\begin{frame}
\frametitle{Approximate $\vEnd_{t}^{\prime}(\aRat)$?}
Better ... but still violates first two principles:
\includegraphics[width=4in]{./Figures/PlotOPRawVSFOC.pdf}
\end{frame}
\end{comment}
\subsection{The Method of Endogenous Gridpoints}
\begin{frame}
\frametitle{Solution: The Method of Endogenous Gridpoints}
\pause
\begin{itemize}
\item Define vector of {\it end-of-period} asset values $\vec{\aRat}$
\item For each $\aRat[j]$ compute $\vEnd_{t}^{\prime}(\aRat[j])$
\end{itemize}
\pause
Each of these $\vEnd_{t}^{\prime}[j]$ corresponds to a unique
$\cNrm[j]$ via FOC:
\begin{equation}\begin{gathered}\begin{aligned}
\cNrm[j]^{-\CRRA} & = \vEnd_{t}^{\prime}(\aRat[j])
\\ \cNrm[j] & = \left(\vEnd_{t}^{\prime}(\aRat[j])\right)^{-1/\CRRA}
\end{aligned}\end{gathered}\end{equation}
\pause
But the DBC says
\begin{equation}\begin{gathered}\begin{aligned}
\aRat_{t} & = \mRat_{t} - \cNrm_{t}
\\ \mRat[j] & = \aRat[j]+\cNrm[j]
\end{aligned}\end{gathered}\end{equation}
\pause
So computing $\vEnd_{t}^{\prime}$ at a vector of $\vec{\aRat}$ values has produced for us the corresponding $\vec{\cNrm}$ and $\vec{\mRat}$
values at virtually no cost!
\pause
\medskip
From these we can interpolate as before to construct $\grave{\cFunc}_{t}(\mRat)$.
\end{frame}
\begin{frame}
\frametitle{Why Directly Approximating $\vFunc_{t}$ is a Bad Idea}
Principles of Approximation
\begin{itemize}
\item Hard to approximate things that approach $\infty$ for relevant $\mRat$
\begin{itemize}
\item Not a prob for Rep Agent models: `relevant' $\mRat$'s are $\approx$ SS
\end{itemize}
\item Hard to approximate things that are highly nonlinear
%\item Best to approximate things that directly govern behavior
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Approximate Something That Would Be Linear in PF Case}
\medskip
Perfect Foresight Theory:
\begin{equation}\begin{gathered}\begin{aligned}
\cFunc_{t}(\mRat) & = (\mRat+\hEnd_{t})\MPCmin_{t}
\end{aligned}\end{gathered}\end{equation}
for market resources $\mRat$ and end-of-period human wealth $\hEnd$.
\medskip\medskip
\pause
This is why it's a good idea to approximate $\cFunc_{t}$
\pause \medskip\medskip
Bonus: Easy to debug programs by setting $\sigma^{2} = 0$ and
testing whether numerical solution matches analytical!
\end{frame}
\subsection{Approximate Inverted Functions}
\begin{frame}%[ValFnApprox]
\frametitle{But What if You {\it Need} the Value Function?}
Perfect foresight value function:
\input{./Equations/vFuncPF.tex}
which is linear.
\medskip\medskip
\pause If you need the value function, approximate the {\it inverted} value function to generate $\grave{\vInv}_{t}$
and then obtain your approximation from
\begin{equation}\begin{gathered}\begin{aligned}
\grave{\vFunc}_{t} & = \util(\grave{\vInv}_{t})
\end{aligned}\end{gathered}\end{equation}
\end{frame}
\subsection{Derivatives}
\begin{frame}
\frametitle{Approximate Slope Too}
\cite{BufferStockTheory} shows that $\cFunc^{\mRat}_{t}$ exists everywhere.
\medskip
\pause
Define {\it consumed} function and its derivative as
\begin{equation}\begin{gathered}\begin{aligned}
\cEndFunc_{t}(\aRat) & = (\vEnd^{\prime}_{t}(\aRat))^{-1/\CRRA}
\\ \cEndFunc_{t}^{\aRat}(\aRat) & = -(1/\CRRA)\left(\vEnd_{t}^{\prime}({a})\right)^{-1-1/\CRRA} \vEnd_{t}^{\prime\prime}(\aRat)
\end{aligned}\end{gathered}\end{equation}
\pause
and using chain rule it is easy to show that
\begin{equation}\begin{gathered}\begin{aligned}
\cFunc^{\mRat}_{t} & = \cEndFunc^{\aRat}_{t}/(1+\cEndFunc^{\aRat}_{t})
\end{aligned}\end{gathered}\end{equation}
\end{frame}
\begin{frame}
\frametitle{To Implement: Modify Prior Procedures in Two Ways}
\begin{enumerate}
\item Construct $\vec{\cFunc}^{\mRat}_{t}$ along with $\vec{\cFunc}_{t}$ in EGM algorithm
\item Approximate $\cFunc_{t}(m)$ using piecewise Hermite polynomial
\begin{itemize}
\item Exact match to both level and derivative at set of points
\end{itemize}
\end{enumerate}
\end{frame}
\subsection{Improving the $\aRat$ Grid}
\begin{frame}
\frametitle{Problem: $\Alt{\cFunc}$ Below Bottom $\mRat$ Gridpoint and Extrapolation}
Consider what happens as ${a}_{T-1}$ approaches $\underline{a}_{T-1}\equiv-\underline{\TranShkEmp}\RNrm_{T}^{-1}$,
\begin{equation*}\begin{gathered}\begin{aligned}
\lim_{{\aRat} \downarrow \underline{a}_{T-1}} \vEnd_{T-1}^{\prime}({\aRat})
& = \lim_{{\aRat} \downarrow \underline{a}_{T-1}} \Discount \Rfree \PermGroFac_{T}^{-\CRRA} \left(\frac{1}{n}\right) \sum_{i=1}^{n} \left( {\aRat} \RNrm_{T}+ \TranShkEmp_{i}\right)^{-\CRRA}
\\ & = \infty
\end{aligned}\end{gathered}\end{equation*}
This means our lowest value in $\vec{\aRat}_{T-1}$ should be $> \underline{\aRat}_{T-1}$.
\medskip
Suppose we construct $\Alt{\cFunc}$ by linear interpolation:
\begin{equation*}\begin{gathered}\begin{aligned}
\Alt{\cFunc}_{T-1}(\mRat) & = \Alt{\cFunc}_{T-1}(\vec{\mRat}_{T-1}[1])+\Alt{\cFunc}_{T-1}^{\prime}(\vec{\mRat}_{T-1}[1])({\mRat}-\vec{\mRat}_{T-1}[1]) \label{eq:ExtrapLin}
\end{aligned}\end{gathered}\end{equation*}
True $\cFunc$ is strictly concave
$\Rightarrow \exists \mRat^{-} > \underline{\mRat}_{T-1}$ for which $\mRat^{-}-\Alt{\cFunc}_{T-1}(\mRat^{-}) < \underline{\aRat}_{T-1}$
\end{frame}
\begin{frame}
\frametitle{Solution: Hard-Code the Bottom Point}
Theory says that
\begin{equation}\begin{gathered}\begin{aligned}
\lim_{\mRat \downarrow \underline{\mRat}_{T-1}} \cFunc_{T-1}(\mRat) & = 0
\\ \lim_{\mRat \downarrow \underline{\mRat}_{T-1}} \cFunc_{T-1}^{\mRat}(\mRat) & = \MPCmax_{T-1}
\end{aligned}\end{gathered}\end{equation}
\medskip
\begin{enumerate}
\item Redefine $\vec{\aRat}$ {\it relative} to $\uline{\aRat}_{T-1}$
\item Construct corresponding $\vec{\mRat}_{T-1}$ and $\vec{\cNrm}_{T-1}$
\item Prepend $\uline{\mRat}_{T-1}$ to $\vec{\mRat}_{T-1}$
\item Prepend $0.$ to $\vec{\cNrm}_{T-1}$
\item Prepend $\MPCmax_{T-1}$ to $\vec{\MPC}_{T-1}$
\end{enumerate}
then proceed as before.
\end{frame}
\begin{frame}
\frametitle{Trick: Improving the $\aRat$ Grid}
Grid Spacing: Uniform
\includegraphics[width=4in]{./Figures/GothVInvVSGothC.pdf}
\end{frame}
\begin{frame}
\frametitle{Trick: Improving the $\aRat$ Grid}
Grid Spacing: Same $\{\uline{\aRat},\bar{\aRat}\}$ But Triple Exponential $e^{e^{e^{...}}}$ Growth
\includegraphics[width=4in]{./Figures/GothVInvVSGothCEEE.pdf}
\end{frame}
\subsection{The Method of Moderation}
\begin{frame}[label=MoM]
\frametitle{The Method of Moderation}
\begin{itemize}
\item Further improves speed and accuracy of solution
\item See my talk at the conference!
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Imposing `Artificial' Borrowing Constraints}
\input{./Equations/ConstrArt.tex}
\pause
Define $\grave{\cFunc}^{*}_{t}$ as soln to unconstrained problem. Then
\input{./Equations/LiqCons.tex}
\end{frame}
\begin{frame}
\frametitle{Imposing `Artificial' Borrowing Constraints}
Point where constraint makes transition from binding to not is
\begin{equation*}\begin{gathered}\begin{aligned}
\util^{\prime}(\mRat_{T-1}^{\#}) & = \vEnd^{\prime}_{T-1}(0.)
\\ \mRat_{T-1}^{\#} & = \left(\vEnd^{\prime}_{T-1}(0.)\right)^{-1/\CRRA}
\end{aligned}\end{gathered}\end{equation*}
\pause\medskip
Procedure is very easy:
\begin{itemize}
\item Add $0.$ as first point in $\vec{\aRat}$
\item $\Rightarrow \vec{\mRat}[1] = \mRat_{T-1}^{\#}$
\item Above $\mRat_{T-1}^{\#}$, $\grave{\cFunc}_{T-1}(\mRat)$ obtained as before
\item Below $\mRat_{T-1}^{\#}$, $\grave{\cFunc}_{T-1}(\mRat)=\mRat$
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Imposing `Artificial' Borrowing Constraints}
\begin{figure}
\includegraphics[width=4in]{./Figures/cVScCon.pdf}
\caption{Constrained (solid) and Unconstrained (dashed) Consumption}
\label{fig:cVScCon}
\end{figure}
\end{frame}
\begin{frame}%[Recursion]
\frametitle{Recursion: Period $t$ Solution Given Period $t+1$}
\begin{enumerate}
\item Construct
\input{./Equations/vEndeq.tex}
\item Call the result $\vec{\cNrm}_{t}$ and generate the corresponding $\vec{\mRat}_{t}=\vec{\cNrm}_{t}+\vec{\aRat}_{t}$
\item Interpolate to create $\grave{\cNrm}_{t}(\mRat)$
\end{enumerate}
\end{frame}
\begin{frame}%[Convergence]
\frametitle{Consumption Rules $\grave{\cFunc}_{T-n}$ Converge}
\begin{figure}
\includegraphics[width=4in]{./Figures/PlotCFuncsConverge.pdf}
\caption{Converging $\grave{\cFunc}_{T-n}({\mRat})$ Functions for $n=\{1,5,10,15,20\}$}
\label{fig:PlotCFuncsConverge}
\end{figure}
\end{frame}
\section{Multiple Control Variables}
\begin{frame}
\frametitle{Portfolio Choice}
Now the consumer has a choice between a risky and a safe asset. \pause The portfolio
return is
\input{./Equations/Rport.tex}
\pause so (setting $\PermGroFac=1$) the maximization problem is \pause
\input{./Equations/PortProb.tex}
\end{frame}
\begin{frame}
\frametitle{Portfolio Choice}
The FOC with respect to $\cNrm_{t}$ now yields an Euler equation
\input{./Equations/EulercRiskyR.tex}
\pause
while the FOC with respect to the portfolio share yields
\input{./Equations/FOCw.tex}
\end{frame}
\section{The Infinite Horizon}
\subsection{Convergence}
\begin{frame}
\frametitle{Convergence}
When the problem satisfies certain conditions~(\cite{BufferStockTheory}),
it defines a `converged' consumption rule with a `target' ratio $\check{\mRat}$
that satisfies:
\begin{equation}\begin{gathered}\begin{aligned}
\Ex_{t}[\mRat_{t+1}/\mRat_{t}] & = 1 \text{~if $\mRat_{t} = \check{\mRat}$}
\end{aligned}\end{gathered}\end{equation}
\pause
Define the target $\mRat$ implied by the consumption rule $\cFunc_{t}$ as $\check{\mRat}_{t}$.
\medskip\pause
Then a plausible metric for convergence is to define some value $\epsilon$ and to declare
the solution to have converged when
\begin{equation}\begin{gathered}\begin{aligned}
|\check{\mRat}_{t+1}-\check{\mRat}_{t}| & < \epsilon
\end{aligned}\end{gathered}\end{equation}
\end{frame}
\subsection{Tricks}
\begin{frame}
\frametitle{Trick: Coarse then Fine $\TranShkEmp$}
\begin{enumerate}
\item Start with coarse grid for $\TranShkEmp$ (say, 3 points)
\item Solve to convergence; call period of convergence $n$
\item Construct finer grid for $\TranShkEmp$ (say, 7 points)
\item Solve for period $T-n-1$ assuming $\Alt{\cFunc}_{T-n}$
\item Continue to convergence
\end{enumerate}
\end{frame}
\begin{frame}
\frametitle{Trick: Coarse then Fine $\vec{\aRat}_{T-1}$}
\begin{enumerate}
\item Start with coarse grid for $\vec{\aRat}$ (say, 5 gridpoints)
\item Solve to convergence; call period of convergence $n$
\item Construct finer grid for $\vec{\aRat}$ (say, 20 points)
\item Solve for period $T-n-1$ assuming $\Alt{\cFunc}_{T-n}$
\item Continue to convergence
\end{enumerate}
\end{frame}
\section{Structural Estimation}
\subsection{Life Cycle Model}
\begin{frame}
\frametitle{Life Cycle Maximization Problem}
\input{./Equations/LifeCycleMaxNormed.tex}
\input{./Equations/subjectTo.tex}
\end{frame}
\begin{frame}
\frametitle{Details follow~\cite{cagettiWprofiles}}
\begin{itemize}
\item Parameterization of Uncertainty
\item Probability of Death
\item Demographic Adjustments to $\Discount$
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Empirical Wealth Profiles}
\begin{figure}
\includegraphics[width=3.5in]{./Figures/PlotMeanMedianSCFcollegeGrads.pdf}
\caption{$\mRat$ from SCF (means (dashed) and medians (solid))}
\label{fig:MeanMedianSCF}
\end{figure}
\end{frame}
\begin{frame}
\frametitle{Simulated Moments}
Given a set of parameter values $\{\CRRA,\beth\}$:
\begin{itemize}
\item Start at age 25 with empirical $\mRat$ data
\item Draw shocks using calibrated $\sigma^{2}_{\PermShk}$,$\sigma^{2}_{\TranShkEmp}$
\item Consume according to solved $\cFunc_{t}$
\end{itemize}
\pause
$\Rightarrow \mRat$ distribution by age
\end{frame}
\begin{frame}
\frametitle{Choose What to Simulate}
\input{./Equations/GapEmpiricalSimulatedMedians.tex}
\end{frame}
\begin{frame}
\frametitle{Calculate Match Between Theory and Data}
\begin{equation}\begin{gathered}\begin{aligned}
\xi & = \{\CRRA,\beth\}
\end{aligned}\end{gathered}\end{equation}
solve
\input{./Equations/StructEstim.tex}
\end{frame}
\begin{frame}
\frametitle{Bootstrap Standard Errors (\cite{horowitzBootstrap})}
Yields estimates of
\input{./Tables/EstResults.tex}
\end{frame}
\begin{frame}
\frametitle{Contour Plot}
\begin{figure}
\includegraphics[width=2.5in]{./Figures/PlotContourMedianStrEst.pdf}
\caption{Point Estimate and Height of Minimized Function}
\label{fig:PlotContourMedianStrEst}
\end{figure}
\end{frame}
\beamerdefaultoverlayspecification{<*>}
\begin{frame}[allowframebreaks]
\frametitle{\textbf{References}}
\tiny
\input handoutBibMake
\end{frame}
\end{document}