早上好，我的 Latex (Overleaf) 项目出了问题。昨晚还运行正常，但今天早上，下面的错误信息一直出现。
参数失控？{\headcommand 扫描 \@writefile 的使用时文件结束。\par l.25 \begin{document
我想知道我的日志文件出了什么问题。如果有人能帮我完成这项重要的任务，那将非常有帮助！提前谢谢您！
\documentclass{beamer}
\mode<presentation>
{
\usetheme{default} % or try Darmstadt, Madrid, Warsaw, ...
\usecolortheme{beaver} % or try albatross, beaver, crane, ...
\usefonttheme{default} % or try serif, structurebold, ...
\setbeamertemplate{navigation symbols}{}
\setbeamertemplate{caption}[numbered]
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\usepackage[english]{babel}
\usepackage[utf8x]{inputenc}
\begin{document}
\begin{frame}
\titlepage
\end{frame}
\begin{frame}{Table of Contents}
\tableofcontents
\end{frame}
\section{I. Introduction}
\begin{frame}{I. Introduction}
\begin{itemize}
\item Objective: To investigate the effect of the supply of birth control methods on fertility behavior by examining Romania's 23-year period of pronatalist policies
\item Whether family planning programs have an effect on female fertility
\end{itemize}
\begin{block}{\textbf{Romania's Distinctive History of Changes in access to Birth Control Method}}
i) 1957-1966, Very liberal abortion policy and abortion was the main method of contraception.
ii) 1966, The government abruptly made abortion and family planning illegal.
iii) December 1989, With the fall of communism, Romania reverted back to a liberal policy regarding abortion and modern contraceptives.
\end{block}
\end{frame}
\begin{frame}{I. Introduction}
\textbf{Extensions from Previous Works}
1) Romania restricted access not just to abortion but also to other birth control methods.
2) Romania's 23-year period (1967-89) of restricted access to abortion and birth control methods also allows for an evaluation of the long-term fertility impacts of supply restrictions.
3) The heterogeneous effect of the policy by educational status can be explored with detailed reproductive microdata.
\vspace{0.5cm}
\textbf{Empirical Strategy}
1) To study reproductive outcomes of women in the period 1988-1992 just before and after the policy shifts (legalizing abortion in Dec. 1989 in Romania)
2) To compare those outcomes with outcomes of similar women in neighboring Moldova.
\end{frame}
\begin{frame}{I. Introduction}
\textbf{Empirical Strategy}
3) Analyzing monthly fertility patterns in Romania during 19990 to explore immediate effects six months after the policy change.
4) To examine the longer-term patterns of fertility levels across policy regimes looking at cohorts of Romanian and Hungarian women in Romania, compared to similar cohorts from Hungary
\vspace{0.5cm}
\textbf{Main Findings}
1) The supply of birth control methods has a large effect on fertility levels.
2) A large part of the fertility differentials across educational groups is shown.
3) In the short-run, the lifting of the restrictive ban in 1989 decreased fertility by 30 percent. 23-year restrictive policies brought large increases in lifecycle fertility.
4) Bigger changes are shown among less educated women.
\end{frame}
\section{II. Abortion and Birth Control Policies Regimes in Romania}
\begin{frame}{II. Abortion and Birth Control Policies Regimes in Romania}
\begin{itemize}
\item Romania has long been an "special situation" in the field of demography and reproductive behavior because of the radical changes in policy concerning access to legal abortion.
\begin{center}
\includegraphics[scale = .55]{Figure1_Total_Fertility_Rates.png}
\end{center}
\item Potential Confounding Effect i) pronatalist incentives from 1966 ii) Transition Process
\end{itemize}
\end{frame}
\section{III. Data and Econometric Framework}
\begin{frame}{III. Data and Econometric Framework}
\begin{itemize}
\item 1993 Romanian Reproductive Health Survey
\item The retrospective survey covers the reproductive outcomes of women both before and after the ban on abortions and birth control was lifted in December 1989.
\item In 1993, abortion had already been legalized for a number of years thus women were more likely to report their use of illegal abortions prior to 1989.
\item For the robustness of the results, this analysis will include data from \textbf{1) 1997 Moldova Reproductive Health Survey} - (i) No restriction on access to abortion or modern contraception (ii) Majority in Moldova is Romanian (iii) Experience of economic and political transition from communism in the 1990s (iv) Similar format
\item \textbf{2) Sample of the 1992 Romanian Census 3) the 1990 Hungarian Census}
\end{itemize}
\end{frame}
\begin{frame}{III. Data and Econometric Framework}
\begin{center}
\includegraphics[scale=.55]{Table_1.png}
\end{center}
\end{frame}
\begin{frame}{III. Data and Econometric Framework}
\begin{flalign*}
OUTCOME_{it}
& = \beta_{0} + \beta_{1} \cdot education + \beta_{2} \cdot after_{t} + \beta_{3} \cdot education_{it} \cdot after_{t}
& + \beta_{4} \cdot agegroup_{it} + \beta_{5} \cdot agegroup_{it} \cdot after_{t} + \epsilon_{it}
\end{flalign*}
\begin{itemize}
\item $OUTCOME_{it}$ : the number of pregnancies/births/abortions that occur to a particular person (\textit{i}) in a given year (\textit{t})
\item $education$ : 1 if an individual had more than primary school
\item $after$: 1 if an event occurred between 1991 and 1992, 0 otherwise
\item $agegroup$ : 5 dummies with the 20-24 years dummy dropped
\item $\beta_{2}$ : The overall impact of the change in abortion and modern contraception regime on the reproductive outcome of interest for the less educated
\item $\beta_{2}+\beta_{3}$ : the effect on the educated
\item $\beta_{1}$ : difference between less educated and more educated women prior to reform
\item $\beta_{1}+\beta_{3}$ : difference across educational groups after the reform
\end{itemize}
\end{frame}
\section{IV. Results}
\begin{frame}{IV. Results}
\begin{block}{A. Graphical analysis and regression results}
\begin{center}
\includegraphics[scale=.35]{Figure_234.png}
\end{center}
\end{block}
\end{frame}
\begin{frame}{IV. Results}
\begin{center}
\includegraphics[scale=.25]{Table_2.png}
\end{center}
\begin{tabular}{lll|rr}
Category & Before & After & Difference\\\hline
Uneducated & 0 & $\beta_{2}$ = -0.068 & -0.068\\
Educated & $\beta_{1}$ = 0.051 &$\beta_{1}$ + $\beta_{2}$ + $\beta_{3}$ = -0.089 & -0.038
\end{tabular}
\begin{itemize}
\item(1) The supply of birth control methods has a large impact on fertility levels.
\item(2) It explains a large part of the fertility differential between educated and uneducated women
\end{itemize}
\end{frame}
\begin{frame}{IV. Results}
\begin{center}
\includegraphics[scale=.35]{Table_3.png}
\begin{itemize}
\item \textbf{Women tend to underreport unwanted births} given that the coefficients on \textit{after} and the interaction of \textit{education} and \textit{after} are much larger for births than for unwanted births.
\end{itemize}
\end{center}
\end{frame}
\begin{frame}{IV. Results}
\begin{center}
\includegraphics[scale=.12]{Table_4.png}
\end{center}
\begin{itemize}
\item \textbf{Controls for SES} Basic household amenities as well as urban, region, and religion dummies \item \textbf{Reverse Causality} Restricting the sample to individuals aged 20 or higher during each risk period \item \textbf{Fixed Effects Regressions}
\end{itemize}
\end{frame}
\begin{frame}{IV.Results}
\textbf{B.Economic transition vs. Birth Control Access: Comparison with Moldova}
\begin{itemize}
\item Changes in the demand for children due to the different social and economic environment following the fall of communism. (Decrease in fertility during the transition year)
\item Similar micro data from Romania and Moldova
\begin{flalign*}
OUTCOME_{itr}
& = \theta_{0} + \theta_{1} \cdot education_{itr} + \theta_{2} \cdot after_{t} \\
& + \theta_{3} \cdot education_{itr} \cdot after_{t} + \theta_{4} \cdot romania_{r} \\
& + \theta_{5} \cdot romania_{r} \cdot after_{t} + \theta_{6} \cdot romania_{r} \cdot education_{itr} \\
& + \theta_{7} \cdot education_{itr} \cdot after_{t} \cdot education_{itr} \\
& + \theta_{8} \cdot agegroup_{it} + \theta_{9} \cdot agegroup_{it} \cdot after_{t} \\
& + \epsilon_{it}
\end{flalign*}
\item $\theta_{5}$, $\theta_{6}$, $\theta_{7}$ : The responses in reproductive behavior after 1990 for different educational groups that are particular for Romania after controlling for common trends in the two countries.
\end{itemize}
\end{frame}
\begin{frame}{IV. Results}
\begin{center}
\includegraphics[scale=.5]{Table_5.png}
\begin{itemize}
\item Decrease in fertility was larger in Romania relative to Moldova.
\item Decrease in births was more pronounced for the uneducated group in Romania.
\item Moldova also experienced decreases in fertility during this time.
\end{itemize}
\end{center}
\end{frame}
\begin{frame}{IV. Results}
\textbf{C. The immediate fertility response in Romania in 1990}
\begin{itemize}
\item Analyze the fertility response in the months immediately following the policy.
\item \textbf{Effects from the economic and political transition:} i) The change in expectations about the future as the result of the change to a democratic society. ii) How the continuing worsening in socioeconomic conditions affects the decision to have children.
\begin{center}
\includegraphics[scale=.5]{Figure_5.png}
\end{center}
\end{itemize}
\end{frame}
\begin{frame}{IV. Results}
\begin{center}
\includegraphics[scale=.38]{Figure_6.png}
\end{center}
\begin{itemize}
\item The fertility response was a lot larger for women with primary education.
\item Large reduction in the fertility gap between educational groups following the reform.
\item Fertility rates are stable and not trending in the period prior to the policy change.
\end{itemize}
\end{frame}
\begin{frame}{IV. Results}
\textbf{D. Long-term impact of the restrictive policy}
\begin{itemize}
\item To track changes in fertility levels over time for women who have spend different fractions of their reproductive years during the 23-year period of restrictive access to contraception.
\item What would have happened in the absence of the restrictive policy by selecting a comparison population that displays close similarities to the treated group.
\item Comparison between Hungarian population living in Romania and the population of Hungary.
\end{itemize}
\end{frame}
\begin{frame}{IV. Results}
\begin{center}
\includegraphics[scale=.3]{Figure_7.png}
\begin{itemize}
\item Difference in fertility between two cohorts is 0.4 children
\item Similar trends in fertility for Hungarians in both countries for women born prior to 1930
\item Women who spent most of their reproductive years under the restrictive regime had a lifetime increase in fertility of about 0.5 children or a 25percent increase
\end{itemize}
\end{center}
\end{frame}
\begin{frame}{IV. Result}
\begin{center}
\includegraphics[scale=0.13]{Figure_8.png}
\begin{itemize}
\item Differential shows a gradual decline over time for cohorts born prior to 1930 followed by a gradual increase for cohorts born afterward.
\item The important role played by the supply birth control methods in explaining fertility levels and the relationship between education and fertility.
\end{itemize}
\end{center}
\end{frame}
\section{V. Conclusion}
\begin{frame}{V. Conclusion}
\begin{itemize}
\item Large increase in fertility by pronatalist policies in Romania
\item Larger fertility increases for less-educated women after birth control restrictions were introduced
\item Larger fertility decreases when access restrictions were lifted after 1989.
\item The significant importance that the supply of birth control methods play in understanding fertility levels and the effect of education on fertility.
\item A 30 percent reduction in fertility in Romania six months after the lifting of the ban and a 25 percent reduction in lifetime fertility.
\end{itemize}
\end{frame}
\end{document}