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20 | 20 | \textcolor{columbiadarkblue}{ECON G6905\\ |
21 | 21 | Topics in Trade\\ |
22 | 22 | Jonathan Dingel\\ |
23 | | -Autumn \the\year, Week 11} |
| 23 | +Spring \the\year, Week 11} |
24 | 24 | \vfill |
25 | 25 | \includegraphics[width=0.4\textwidth]{../images/Columbia_logo.png} |
26 | 26 | \end{center} |
|
54 | 54 | \item {Estimating logit model by Poisson regression is Guimar{\~a}es, Figueiredo, Woodward ``\href{https://ideas.repec.org/a/tpr/restat/v85y2003i1p201-204.html}{A Tractable Approach To The Firm Location Decision Problem}'' (2003)\par} |
55 | 55 | }\end{itemize} |
56 | 56 | Plain-vanilla logit case: |
57 | | -individual $i$ considers choice $j$ (see \href{https://eml.berkeley.edu/books/choice2.html}{Train 2009}) |
| 57 | +individual $i$ considers choice $j$ (see \href{https://eml.berkeley.edu/books/choice2.html}{Train 2009} Ch. 3) |
58 | 58 | \begin{itemize} |
59 | 59 | \item Utility $U_{ij} = V_{ij} + \epsilon_{ij}$ |
60 | | - \item Assume error is iid Gumbel (T1EV): $F\left(\epsilon_{ij}\right)=\exp(-\exp(-\epsilon_{ij}))$ |
| 60 | + \item Assume error is iid standard Gumbel (T1EV): $F\left(\epsilon_{ij}\right)=\exp(-\exp(-\epsilon_{ij}))$ |
61 | 61 | \item Choice probabilities are |
62 | 62 | \begin{equation*}\Pr(U_{ij}>U_{ij'} \ \forall j' \neq j) = \frac{\exp(V_{ij})}{\sum_{j'}\exp(V_{ij'})} \end{equation*} |
63 | 63 | \end{itemize} |
64 | 64 | \end{frame} |
65 | 65 | % ----------------------------------------- |
66 | 66 | \begin{frame}{Import-sourcing decisions are discrete-choice problems} |
67 | | -Trade models feature discrete-choice problems |
| 67 | +Neoclassical trade models feature discrete-choice problems |
68 | 68 | \begin{itemize} |
69 | | -\item Selecting the least-cost provider of each good/variety is at the heart of neoclassical trade models |
| 69 | +\item Selecting the least-cost provider of each good is at the heart of the model |
70 | 70 | \item In the Eaton and Kortum (2002) formulation, this is probabilistic and a discrete-choice problem |
71 | 71 | \end{itemize} |
72 | 72 | \smallskip |
|
76 | 76 | \item Cost $\ln c_{ji} = \ln c_j + \ln \tau_{ji} - \epsilon_{j}$ |
77 | 77 | \item Least-cost probability |
78 | 78 | \begin{align*} |
79 | | - \Pr(-\ln c_{ji}> -\ln c_{j'i} \ \forall j' \neq j) \\ |
80 | | - = \Pr(\ln c_{ji}<\ln c_{j'i} \ \forall j' \neq j) |
81 | | - & |
82 | | - = \frac{1/(c_j\tau_{ji})}{\sum_{j'}1/(c_{j'}\tau_{j'i})} \\ |
| 79 | + \Pr(\ln c_{ji}<\ln c_{j'i} \ \forall j' \neq j) |
| 80 | + = |
| 81 | + \Pr(-\ln c_{ji}> -\ln c_{j'i} \ \forall j' \neq j) |
| 82 | + = |
| 83 | + \frac{1/(c_j\tau_{ji})}{\sum_{j'}1/(c_{j'}\tau_{j'i})} |
83 | 84 | \end{align*} |
84 | 85 | \end{itemize} |
| 86 | +\textcolor{gray}{Gumbel CDF is $F\left(\epsilon\right)=\exp(-\exp((\mu-\epsilon)/\beta))$. Standard Gumbel is $\mu=0,\beta=1$.} |
85 | 87 | \textcolor{gray}{The Frechet distribution is the log-Gumbel distribution.} |
86 | 88 | \end{frame} |
87 | 89 | % ----------------------------------------- |
|
200 | 202 | \end{itemize} |
201 | 203 | \end{frame} |
202 | 204 | \begin{frame} |
203 | | -\frametitle{Behavioral model} %TODO |
| 205 | +\frametitle{Behavioral model} |
204 | 206 | \begin{itemize} |
205 | 207 | \item Individual $i$ decides at time $t$ whether to visit venue $j$ in choice set $\mathcal{J}$. |
206 | 208 | \item Trip may originate from one of six locations $l$, $l \in \mathcal{L} = \left\{\textnormal{car},\textnormal{public transit}\right\} \times \{\textnormal{home, work, commute}\}$ |
|
246 | 248 | \Pr(d_{ijt}^{r}=1|d_{ijt}=1,\cdot;\cdot) \times \Pr(d_{ijt}=1|\cdot;\cdot) |
247 | 249 | \\ |
248 | 250 | &= |
249 | | -w_{it} \times \mathbbm{1}\{j\neq 0,j\notin D_{it}^{r}\} \times \Pr(d_{ijt}=1|\cdot;\cdot) |
| 251 | +w_{it} \times \mathbf{1}\{j\neq 0,j\notin D_{it}^{r}\} \times \Pr(d_{ijt}=1|\cdot;\cdot) |
250 | 252 | \end{align*} |
251 | 253 | \pause |
252 | 254 | If $\Pr(d_{ijt}^{r}=1|d_{ijt}=1,\cdot;\cdot)$ depends on some restaurant characteristic in $Z$ |
253 | 255 | \begin{itemize} |
254 | 256 | \item Coefficient on that characteristic would be biased |
255 | 257 | \item Estimates of spatial and social frictions could still be asymptotically unbiased |
256 | 258 | \end{itemize} |
| 259 | +\only<2>{} |
257 | 260 | \end{frame} |
258 | 261 | %------------------------------------------------------------------------------------------- |
259 | 262 | \begin{frame} |
|
284 | 287 | \begin{align*} |
285 | 288 | \Pr(d_{ijt}^{*}=1|d_{it}^{*}=1X,Z,\mathcal{J};\gamma,\beta) |
286 | 289 | &= |
287 | | -\mathbbm{1}\{j\neq 0,j\notin D_{it}^{r}\} \times \Pr(d_{ijt}=1|\cdot;\cdot) |
| 290 | +\mathbf{1}\{j\neq 0,j\notin D_{it}^{r}\} \times \Pr(d_{ijt}=1|\cdot;\cdot) |
288 | 291 | %= |
289 | 292 | %& |
290 | 293 | \\ |
291 | 294 | \implies |
292 | 295 | \Pr(d_{ijt}^{*}=1|d_{it}^{*}=1,X_{i},Z_{i},S_{it};(\gamma,\beta)) |
293 | 296 | &= |
294 | | -\frac{\mathbbm{1}\{j\in S_{it}\}\sum_{l\in\mathcal{L}}\exp(V_{ijl})}{\sum_{j'\in S_{it}}\sum_{l\in\mathcal{L}}\exp(V_{ij'l})} |
| 297 | +\frac{\mathbf{1}\{j\in S_{it}\}\sum_{l\in\mathcal{L}}\exp(V_{ijl})}{\sum_{j'\in S_{it}}\sum_{l\in\mathcal{L}}\exp(V_{ij'l})} |
295 | 298 | \end{align*} |
296 | 299 | is the probability that $i$ reviews restaurant $j$ at period $t$ conditional on a randomly drawn set $S_{it}$ and that $i$ writes a review at $t$. |
297 | 300 | McFadden (1978) shows that maximizing this likelihood is a consistent estimator (obviously larger standard errors from not using all observations). |
|
370 | 373 | % ----------------------------------------- |
371 | 374 | \begin{frame}{Parametric bootstrap for confidence intervals in DDMM} |
372 | 375 | \vspace{-1mm} |
373 | | -\begin{itemize} |
| 376 | +\begin{itemize}{\small |
374 | 377 | \item Draw 500 samples from estimated model (same size as estimation sample) |
375 | 378 | \item Estimate the model on each generated sample |
376 | 379 | \only<1-2>{\item Distributions for social frictions and restaurant characteristics look like asymptotic normal distribution} |
377 | 380 | \only<3-5>{\item Distributions for spatial frictions have fat tails because of collinearity of same-origin modes (\href{https://davegiles.blogspot.com/2011/09/micronumerosity.html}{see Goldberger} on multicollinearity and micronumerosity)} |
378 | | -\end{itemize} |
| 381 | +}\end{itemize} |
379 | 382 | \vspace{-3mm} |
380 | 383 | \begin{center} |
381 | 384 | \only<1>{Asian reviewers: Social frictions\\ \includegraphics[height=0.6\textheight]{../images/week11/bootstrap_param_mainspec_social_asian.png} } |
|
385 | 388 | \only<5>{Spatial frictions in minimum-time specification $\nu_{ijlt} = \nu_{ijt} \ \forall l$\\ \includegraphics[width=1.0\textwidth]{../images/week11/bootstrap_param_mintime_spatial.png} } |
386 | 389 | \\ \includegraphics[width=0.4\textwidth]{../images/week11/bootstrap_param_legend.png} |
387 | 390 | \end{center} |
| 391 | +\only<5>{} |
388 | 392 | \end{frame} |
389 | 393 | % ----------------------------------------- |
390 | 394 | \begin{frame}{Parametric bootstrap of dissimilarity indices in DDMM} |
|
606 | 610 | \item Smart choices can speed your computations by orders of magnitude |
607 | 611 | \item Econometrics by simulation is often a good starting point |
608 | 612 | \end{itemize} |
609 | | -\end{frame} |
610 | | -% ----------------------------------------- |
611 | | -\begin{frame}{Next week} |
612 | | -\begin{itemize} |
613 | | -\item Spatial policies |
614 | | -\item Any requests? |
615 | | -\end{itemize} |
| 613 | +Next week: Spatial environmental economics |
616 | 614 | \end{frame} |
617 | 615 | % ----------------------------------------- |
618 | 616 | \end{document} |
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