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	pdftitle={Appendix: Political Ambition and Opposition Legislative Review: Bill Scrutiny as an Intra-Party Signaling Device},
	pdfauthor={Lion Behrens, Dominic Nyhuis, Thomas Gschwend},
	pdfsubject={Legislative Behavior, Opposition strategies},
	pdfkeywords={Opposition strategies, legislative amendments, automated text analysis, Germany},
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\author{
	Lion Behrens\\University of Mannheim\\Department of Political Science\\behrens@uni-mannheim.de\\
	\and
    Dominic Nyhuis\\University of Hannover\\Institute of Political Science\\d.nyhuis@ipw.uni-hannover.de
	\and
	Thomas Gschwend\\University of Mannheim\\Department of Political Science\\gschwend@uni-mannheim.de
}

\date{}

\title{Appendix: Political Ambition and Opposition Legislative Review:\\Bill Scrutiny as an Intra-Party Signaling Device}

 

\begin{document}
\maketitle
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\tableofcontents

\newpage 
\onehalfspacing


\section{The Landtag Baden-Württemberg in Comparative Perspective}

There are several advantages of studying the \textit{Landtag Baden-Württemberg}. While the concept of political ambition easily travels across legislatures, as even politicians in national legislatures can strive for career advancement within their assemblies, a state-level parliament provides us with an excellent opportunity to measure political ambition as the potential for advancement is greater in state-level parliaments. As state-level politicians can strive for a national or a European career, we are likely to observe progressive ambition among MPs who hope for horizontal or vertical career advancement.

Three factors make our case particularly suitable. First, the \textit{Landtag Baden-Württemberg} is one of the largest state-level legislatures in Germany, with comparatively high levels of professionalization and legislative capacity (\citealt{Appeldorn2022}). This allows us take advantage of its state-level nature for measuring political ambition, while simultaneously studying a full-time professionalized parliament with similar proceedings as national legislatures. Second, the \textit{Landtag} is subject to high fluctuations in governing coalitions in the time frame of the analysis, making horizontal promotions available to a wide range of MPs. In the three legislative terms, there were three different coalition governments between CDU and FDP (2006-2011), Greens and SPD (2011-2016), as well as between Greens and CDU (2016-2021). Except for the right-wing AfD, which entered the parliament for the first time in 2016, all parties have served in government and opposition at least once since 2006. Therefore, in addition to vertical career trajectories, there is considerable potential for horizontal career mobility. Third, the \textit{Landtag} provides fine-grained data on MPs' behavior. In other parliaments, amendments are often signed by numerous legislators or even the entire party group, making it difficult to attribute amendments to specific MPs in order to measure their individual legislative behavior. In the \textit{Landtag}, only few MPs work on amendments, with most proposals being signed by less than four (mean = 3.67) legislators. Hence the possibility of constructing measures of political ambition as well as individual amendments sets our case apart from other legislatures.

How does our case compare to other parliaments? Table \ref{nationalcomparison} compares the \textit{Landtag} (i) to all German state-level parliaments (ii) and to 18 Western European national assemblies across a range of relevant features. First, it is worth noting that like the \textit{Landtag}, all German state-level parliaments with the exception of the city-states Hamburg and Bremen are full-time parliaments with high levels of professionalization and legislative capacity. Yet, professional subnational parliaments are by no means unique to Germany. In recent decades, scholars have noted that in many federal countries, ``a state (or regional) mandate has [\ldots] become a full-time, long-term, fully paid political job similar to that of national deputies at the federal level'' (\citealt{Borchert2011}). A second trend is the regionalization of formerly unitary states like the UK, Spain or France which has weakened the differences between federal and unitary systems (\citealt{Borchert2011}; \citealt{Capua2022}). State-level parliaments in Germany and a variety of other countries are increasingly similar to national assemblies in terms of compensation, staff, session lengths, and legislative proceedings (see \citealt{Bundi2017}; \citealt{Capua2022}; \citealt{Borchert2011}; \citealt{Moncrief1994}).

The \textit{Landtag} is elected using a single vote in a mixed member electoral system without party lists, where district winners receive their seats and the remaining seats are distributed among the best performing runner-ups. While this electoral system is rather unique, in the context of our research question this renders the \textit{Landtag} closer to a least-likely case. The absence of party lists incentivizes ambitious MPs to focus their resources on legislative activities that are directly visible to the electorate such as speeches or parliamentary questions instead of technical amendments in closed committee meetings. Hence, we believe that evidence from the \textit{Landtag} generalizes well to other list systems where the career of MPs depends even more on the party leadership. 

The \textit{Landtag} shares various institutional features with other European legislatures (\citealt{Strom1995}) which are relevant for the study of legislative review. First, the \textit{Landtag} is characterized by a strong committee system, where standing committees shadow ministerial jurisdictions, and the party composition of the committee members is proportional to the plenary. Across the three legislative periods in our study, between ten and twelve standing committees were created per term and, as is common practice in Western European democracies, virtually every piece of legislation was reviewed by at least one committee. In a comparison of national European legislatures provided in Table \ref{internationalcomparison}, we show that national legislatures employ between six (France, Greece) and 29 (Netherlands) legislative committees (median = 12). In the \textit{Landtag} and in virtually all national assemblies, committees either have the right to rewrite bills or to propose bill amendments which are considered and voted upon side-by-side with the original bill (see also \citealt{Strom1995}). This is similar to the findings by \citet{Zubek2021} who documents that it is predominantly the Eastern European national assemblies who often lack rewriting authority.

In sum, while there is considerable variation in the design of legislative institutions, our case is comparable with most other European legislatures in terms of the committee design and rewriting authority which is crucial for the study of legislative review. The aspects where we observe deviations, such as the electoral system, place the \textit{Landtag} closer to a least-likely case. Additionally, since we are dealing with a professionalized parliament composed of full-time politicians, the results generalize well to national-level legislatures, while keeping the advantages that stem from studying a sub-national case.

\newpage

\begin{landscape}


\begin{table}[H]
\caption{The Landtag Baden-Württemberg in national comparison}
\label{nationalcomparison}
\resizebox{1.4\textwidth}{!}{
\begin{tabular}{llllll}
\hline
\textit{Landtag}       & \textit{Full-time} & \textit{Electoral system}                                                                    & \textit{\begin{tabular}[c]{@{}l@{}}Number of \\ permanent committees\end{tabular}} & \textit{\begin{tabular}[c]{@{}l@{}}Committee meetings\\ open to the public\end{tabular}}                           & \textit{\begin{tabular}[c]{@{}l@{}}Existence of \\ subcommittees\end{tabular}} \\ \hline
\rowcolor[HTML]{C0C0C0} 
Baden-Württemberg      & Yes                & \begin{tabular}[c]{@{}l@{}}MMS\end{tabular} & 16                                                                                 & Closed                                                                                                             & Yes                                                                            \\
Bayern                 & Yes                & MMS                                                                                          & 14                                                                                 & Open to public                                                                                                     & Yes                                                                            \\
Berlin                 & Yes                & MMS                                                                                          & 16                                                                                 & \begin{tabular}[c]{@{}l@{}}Open to public, except for petition \\ committee and several subcommittees\end{tabular} & Yes                                                                            \\
Brandenburg            & Yes                & MMS                                                                                          & 15                                                                                 & Open to public                                                                                                     & Yes                                                                            \\
Bremen                 & No                 & PR with open lists                                                                                 & 18                                                                                 & NA                                                                                                                 & Yes                                                                            \\
Hamburg                & No                 & PR with open lists                                                                                   & 26                                                                                 & \begin{tabular}[c]{@{}l@{}}Open to public, except for petition \\ committee\end{tabular}                           & Yes                                                                            \\
Hessen                 & Yes                & MMS                                                                                          & 17                                                                                 & Closed                                                                                                             & Yes                                                                            \\
Mecklenburg-Vorpommern & Yes                & MMS                                                                                          & 9                                                                                  & Closed                                                                                                             & NA                                                                             \\
Niedersachsen          & Yes                & MMS                                                                                          & 11                                                                                 & Open to public                                                                                                     & Yes                                                                            \\
Nordrhein-Westfalen    & Yes                & MMS                                                                                          & 24                                                                                 & Open to public                                                                                                     & Yes                                                                            \\
Rheinland-Pfalz        & Yes                & MMS                                                                                          & 18                                                                                 & NA                                                                                                                 & Yes                                                                            \\
Saarland               & Yes                & MMS                                                                                          & 13                                                                                 & NA                                                                                                                 & Yes                                                                            \\
Sachsen                & Yes                & MMS                                                                                          & 11                                                                                 & Closed                                                                                                             & Yes                                                                            \\
Sachsen-Anhalt         & Yes                & MMS                                                                                          & 12                                                                                 & Open to public                                                                                                     & Yes                                                                            \\
Schleswig-Holstein     & Yes                & MMS                                                                                          & 8                                                                                  & \begin{tabular}[c]{@{}l@{}}Open to public, except for petition \\ committee\end{tabular}                           & Yes                                                                            \\
Thüringen              & Yes                & MMS                                                                                          & 12                                                                                 & \begin{tabular}[c]{@{}l@{}}Depends on decision of the \\ respective committee\end{tabular}                         & Yes                                                                            \\ \hline
\end{tabular}
}
\textit{Source:} Own research. MMS = Mixed Member Proportional Representation. PR = Proportional Representation. 
\end{table}

\newpage 

\begin{table}[]
\caption{The Landtag of Baden-Württemberg in international comparison}
\label{internationalcomparison}
\resizebox{1.4\textwidth}{!}{
\begin{tabular}{llllll}
\hline
\textit{Parliament (Lower House)}                                                                    & \textit{Electoral system}     & \textit{\begin{tabular}[c]{@{}l@{}}Number of permanent committees\\ (legislative by function/specialized/\\ non-legislative)\end{tabular}} & \textit{\begin{tabular}[c]{@{}l@{}}Size of legislative \\ committees\\ (Min/Avg./Max)\end{tabular}} & \textit{Meetings open to the public}                                                                                                                                               & \textit{Rewrite authority}                                                                                                                    \\ \hline
\rowcolor[HTML]{9B9B9B} 
Baden-Württemberg   &MMS                          &16      &22/22/22  &Closed          & Yes\\
Germany             &MMS                          &0/19/2  &13/28/42  &Open to all MPs & \begin{tabular}[c]{@{}l@{}}Committees are free to rewrite \\ government text\end{tabular}\\
Austria             & PR with preferential vote   &0/17/8  &11/21/33  & Other rules    & \begin{tabular}[c]{@{}l@{}}Redraft of bill when substantial \\ amendments are recommended\end{tabular}                                        \\
\begin{tabular}[c]{@{}l@{}}Belgium \end{tabular} & PR with preferential vote   & 1/11/4                                                                                                                                     & 10/22/23                                                                                            & Other rules                                                                                                                                                                        & \begin{tabular}[c]{@{}l@{}}Committees are free to rewrite \\ government text\end{tabular}                                                     \\
\begin{tabular}[c]{@{}l@{}}Denmark\end{tabular}                          & PR with preferential vote   & 0/22/2                                                                                                                                     & 17/17/21                                                                                            & Open to certain MPs                                                                                                                                                                & \begin{tabular}[c]{@{}l@{}}House considers original \\ bill with amendments added\end{tabular}                                     \\
\begin{tabular}[c]{@{}l@{}}Finland\end{tabular}                          & PR with preferential vote   & 1/12/0                                                                                                                                     & 11/17/21                                                                                            & Closed                                                                                                                                                                             & \begin{tabular}[c]{@{}l@{}}Committees are free to rewrite \\ government text\end{tabular}                                                     \\
\begin{tabular}[c]{@{}l@{}}France\end{tabular}                 & Second ballot majority runoff & 1/6/1                                                                                                                                      & 73/97/145                                                                                           & Open to all MPs                                                                                                                                                                    & \begin{tabular}[c]{@{}l@{}}House considers original \\ bill with amendments added\end{tabular}                                     \\
Greece                                                                                 & PR with preferential vote   & 0/6/2                                                                                                                                      & 19/40/55                                                                                            & Open to all MPs                                                                                                                                                                    & \begin{tabular}[c]{@{}l@{}}If redrafted text is not accepted \\ by the relevant minister, chamber \\ considers the original bill\end{tabular} \\
\begin{tabular}[c]{@{}l@{}}Iceland\end{tabular}               & NA                            & 0/9/1                                                                                                                                      & Up to 7                                                                                             & Closed                                                                                                                                                                             & \begin{tabular}[c]{@{}l@{}}Committees are free to rewrite \\ government text\end{tabular}                                                     \\
Ireland                                                                         & STV                           & 0/0/3                                                                                                                                      & 11/19/20                                                                                            & \begin{tabular}[c]{@{}l@{}}Ad-hoc committees are open to public; \\ permanent committees do not consider bills\end{tabular}                                                    & \begin{tabular}[c]{@{}l@{}}House considers original \\ bill with amendments added\end{tabular}                                     \\
\begin{tabular}[c]{@{}l@{}}Italy\end{tabular}                  & Additional member system      & 0/13/6                                                                                                                                     & 25/43/48                                                                                            & Other rules                                                                                                                                                                        & \begin{tabular}[c]{@{}l@{}}Committees are free to rewrite \\ government text\end{tabular}                                                     \\
\begin{tabular}[c]{@{}l@{}}Luxembourg\end{tabular}             & PR with vote-splitting        & 0/19/4                                                                                                                                     & 11/11/13                                                                                            & Closed                                                                                                                                                                             & \begin{tabular}[c]{@{}l@{}}Committees may present substitute texts \\ which are considered with the original text\end{tabular}             \\
\begin{tabular}[c]{@{}l@{}}The Netherlands\end{tabular}               & PR with closed lists          & 0/29/5                                                                                                                                     & 9/22/25                                                                                             & \begin{tabular}[c]{@{}l@{}}Open to public\end{tabular}                                                                                          & \begin{tabular}[c]{@{}l@{}}House considers original \\ bill with amendments added\end{tabular}                                      \\
\begin{tabular}[c]{@{}l@{}}Norway\end{tabular}                            & NA                            & 0/12/4                                                                                                                                     & 10/14/20                                                                                            & Closed                                                                                                                                                                             & Committees are free to rewrite government text                                                                                                \\
\begin{tabular}[c]{@{}l@{}}Portugal \end{tabular}          & PR with closed lists          & 0/12/2                                                                                                                                     & 21/24/35                                                                                            & \begin{tabular}[c]{@{}l@{}}Open to all MPs. Open to the mass media when \\ dealing with legislation. Meetings can be made \\ open to the public by committee decision\end{tabular} & \begin{tabular}[c]{@{}l@{}}Committees may present substitute texts \\ which are considered with the original text\end{tabular}             \\
\begin{tabular}[c]{@{}l@{}}Spain\end{tabular}            & Additional member system      & 0/11/8                                                                                                                                     & 8/41/45                                                                                             & Open to all MPs and the mass media                                                                                                                                                 & Committees are free to rewrite government text                                                                                                \\
\begin{tabular}[c]{@{}l@{}}Sweden\end{tabular}                             & PR with closed lists          & 0/16/1                                                                                                                                     & 15/17/17                                                                                            & Closed                                                                                                                                                                             & Committees are free to rewrite government text                                                                                                \\
\begin{tabular}[c]{@{}l@{}}Switzerland\end{tabular}                    & NA                            & 0/12/0                                                                                                                                     & 11/19/20                                                                                            & Closed                                                                                                                                                                             & Committees are free to rewrite government text                                                                                                \\
\begin{tabular}[c]{@{}l@{}}UK\end{tabular}                        & Simple Majority Vote (FPTP)   & 4/0/19                                                                                                                                     & 11/19/20                                                                                            & Open to public                                                                                                                                                                     & \begin{tabular}[c]{@{}l@{}}House considers original \\ bill with amendments added\end{tabular}                                     \\ \hline
\end{tabular}
}
\textit{Source:} Own research. Similar comparisons can be found in \citet{Strom1995}. STV = Single Transferable Vote. MMS = Mixed Member Proportional Representation. PR = Proportional Representation. FPTP = First Past the Post.
\end{table}


\end{landscape}

\newpage


\section{Associating different measures of political ambition}


\begin{figure}[H]
\singlespacing
  \begin{center}
  \caption{Legislators with and without a Professional Social Media Profile}
\label{twomeasures}
  \includegraphics[width=0.9\textwidth]{ambition.pdf}
\end{center}
\textit{Note: Presented are the shares of MPs who run a professional social media profile on Facebook or Twitter against their candidacy-based classification as exhibiting discrete, static and progressive ambition. The plot is created based on the term $\times$ MP dataset and includes opposition and coalition MPs. Integers in parentheses report the absolute numbers of MPs per group.}
 \end{figure}
 
Figure \ref{twomeasures} relates MPs' social media accounts with the candidacy-based classification as exhibiting discrete, static and progressive ambition. The figure shows a strong association between our two measures of political ambition. Most MPs who are classified as ambitious using our candidacy-based measure receive the same classification based on our social media measure (Cramer’s V= 0.30 [0.21 ; 0.39]\footnote{Reported is the 95\% confidence interval based on 1,000 bootstrap samples.}). As both measures approach political ambition from different perspectives, the strong association between them provides evidence that they measure the same latent trait.


\section{Descriptives on Political Careers of Members of Parliament}

\begin{table}[H]
\singlespacing
\caption{Political Careers of MPs in the Landtag Baden-Württemberg}
\resizebox{\textwidth}{!}{
\begin{tabular}{llllllll}
\hline
\textit{Term}    & \textit{MPs} & \textit{\begin{tabular}[c]{@{}l@{}}Higher Elected \\ Office\end{tabular}} & \textit{\begin{tabular}[c]{@{}l@{}}Executive \\ Leadership\end{tabular}} & \textit{\begin{tabular}[c]{@{}l@{}}Parliamentary \\ Leadership\end{tabular}} & \textit{\begin{tabular}[c]{@{}l@{}}Party Group \\ Leadership\end{tabular}} & \textit{\begin{tabular}[c]{@{}l@{}}Landtag \\ Backbench\end{tabular}} & \textit{Dropout} \\ \hline
14 (2006-2011)   & 154          & 1                                                                         & 16                                                                       & 12                                                                           & 7                                                                          & 51                                                                    & 67               \\
15 (2011-2016)   & 147          & 3                                                                         & 11                                                                       & 16                                                                           & 6                                                                          & 46                                                                    & 65               \\
16 (2016-2021) & 154          & 4                                                                         & 13                                                                       & 11                                                                           & 10                                                                         & 56                                                                    & 60               \\ \hline \hline 
\end{tabular}
}
\label{tab:careers}
\end{table}

Table \ref{tab:careers} describes the career paths of members of the \textit{Landtag Baden-Württemberg} after the legislative term. `Dropout' refers to MPs who did not continue their political career at the state-level or higher. `Landtag Beckbanch' describes members who re-gained a mandate in the \textit{Landtag}, but did not take on a leadership position. `Higher elected office' includes mandates in the Bundestag and the European Parliament. `Executive leadership' includes positions as head of government, minister, or junior minister. `Parliamentary leadership' includes the parliamentary (vice-)presidency, parliamentary chairmen and standing committee chairs. `Party group leadership' includes (co-)managers of party groups. 

\newpage

\section{Investigating the nexus between policy- and vote-motivations and legislative review}

\subsection{Policy motivations}

The paper argues that policy- and vote-motivations are unlikely to underlie the amendment behavior of MPs from non-government parties. Policy-motivations are unlikely as the success rates of opposition amendment proposals are close to zero and MPs are generally well aware of this fact. 

However, the fact that opposition amendments are usually rejected by the parliamentary majority does not preclude that some MPs might use amendment proposals for policy motivations. Specifically, not all MPs might be aware of the dismal success rates of opposition amendments at the beginning of their terms in office. New MPs may believe that they can change policy, but become more realistic over the course of their time in office. Hence, if policy motivations are observed at all, these should be particularly prevalent among new MPs who are unfamiliar with legislative proceedings. In this section, we investigate this alternative individual-level explanation for legislative review. We report three empirical observations.

First, we provide a descriptive analysis contrasting the amendment behavior of new MPs (serving in their first term) and established legislators (see Figures \ref{fig:policy1} and \ref{fig:policy2}). The descriptive patterns are similar for new and experienced MPs. If anything, new MPs are less, not more active. 

Second, we mapped the number of submitted amendments for new MPs across the legislative term (see Figure \ref{fig:policy3}). If MPs start out policy-motivated, but become disillusioned over the course of the legislative term, we should see a greater legislative review effort in the early stages of the legislative period which fades as the term goes on. The figure shows that this is not the case, casting doubt on the possible policy motivation of new MPs who start out unaware of legislative procedures. 

Finally, we have explicitly incorporated the variable ``First Term'' in the statistical models M1-M4 reported in Table 4 in the main text. The coefficient is not statistically different from zero.

\begin{figure}
    \centering
    \includegraphics{policy1.png}
    \caption{Descriptive analysis of legislative efforts for new vs. experienced MPs: Number of submitted amendments}
    \label{fig:policy1}
\end{figure}

\begin{figure}
    \centering
    \includegraphics{policy2.png}
    \caption{Descriptive analysis of legislative efforts for new vs. experienced MPs: Number of submitted article changes}
    \label{fig:policy2}
\end{figure}

\begin{figure}
    \centering
    \includegraphics{policy3.png}
    \caption{Frequency of submitted amendment proposals of first term MPs mapped across the legislative period}
    \label{fig:policy3}
\end{figure}


\subsection{Vote motivations}

We argued that vote-motivations are unlikely as amendment proposals are technical, usually not picked up by the media, and not visible to the electorate. However, MPs may believe that proposing amendments will get them more votes, even if amendments are practically invisible to the public. In this section, we investigate the possibility of vote motivations as an individual-level explanation for legislative review. Again, we report three empirical observations. 

Regarding measurement, our main rationale is that it is straightforward to assume that vote motivations follow from the closeness of the electoral race of an MP. If vote seeking manifests in legislative review, we expect MPs from strongly contested districts to be more active in filing amendments than MPs who won their district by a large margin. Once more, we split the analysis into a descriptive analysis and explicitly incorporate the vote motivation into the models reported in the main text.

First, Figures \ref{fig:vote1} and \ref{fig:vote2} plot the absolute vote share distance between the district winners and the second-placed candidates against their efforts in legislative review. The patterns do not indicate a vote motivation that manifests in amendment behavior, as the extent of legislative review does not systematically vary by the closeness of the electoral race. 

\begin{figure}
    \centering
    \includegraphics{vote1.png}
    \caption{Absolute vote share distance between the district winners and the second-placed candidates versus percentage of bills amended}
    \label{fig:vote1}
\end{figure}

\begin{figure}
    \centering
    \includegraphics{vote2.png}
    \caption{Absolute vote share distance between the district winners and the second-placed candidates versus number of submitted article changes}
    \label{fig:vote2}
\end{figure}

Second, we incorporate the variable ``Closeness of the electoral race'' plotted in Figures \ref{fig:vote1} and \ref{fig:vote2} into the statistical models M1-M4 reported in Table 4 in the main text. All coefficients remain non-significant, which we interpret as robust evidence against vote motivations underlying individual legislative review.

Third, we try out different dummy operationalizations of electoral closeness, binarily separating close districts from uncontested districts. We re-fit models M1-M4 as reported in Table 4 in the main text and create dummy variables separating uncontested districts from contested districts based on different thresholds, ranging from a 15 percentage point gap to a two percentage point gap as cut-off. We plot the coefficients for ``Closeness of the Electoral Race'' and their confidence intervals in Figure \ref{fig:vote3}. By and large, the effects remain non-significant. MPs from uncontested and contested districts are similar in their amendment behavior, which speaks against vote motivations in legislative review by opposition MPs. 

\begin{figure}
    \centering
    \includegraphics{vote3.png}
    \caption{Closeness of the electoral race and opposition legislative review. Re-fitting models M1-M4 from Table 4 under different dummy operationalizations of ``Closeness of the Electoral Race''}
    \label{fig:vote3}
\end{figure}

\section{The relationship between candidacies and legislative review: Probing the causal mechanism}

In the empirical analysis, one of the main measures of political ambition is constructed via candidacies. Drawing on Schlesinger's (\citeyear{Schlesinger1966}) typology of discrete, static and progressive ambition, we measure political ambition via MP’s candidacies separating those who do not get nominated for a political office at the end of the term (discrete ambition), those who aim to return to the \textit{Landtag} (static ambition) and those who aim to rise to a higher-level parliament (progressive ambition).

The reselection of candidates by their local selectorates requires the ambition to put one’s candidature forward, the anticipation that one will be reselected and the actual selection. We argue that our measure grasps the first among these as it is well-documented that the re-nomination of German MPs is not competitive. \citet{Reiser2011} concludes that there was no intra-party challenger in 91.5\% of the district nominations for the \textit{Bundestag}. When considering data from the German Longitudinal Election Study, this figure is 74.77\%. Moreover, \citet{Baumann2017} studied intra-party competition in the re-nomination of German \textit{Bundestag} district candidates and conclude that ``a contested renomination procedure is a relatively rare event for incumbent MPs who seek reelection: Across all parties only slightly more than 10\% of MPS had to compete against one or more contenders.'' (986). In their case study of German MPs for state-level parliaments, the \textit{Bundestag} and the European Parliament, \citet{Best2011} reach the same conclusion. They outline how German parties try to recruit skilled and loyal representatives by minimizing the influence of selectorates on the duration of individual mandates and make MP careers as low-risk as possible (177). If incumbent MPs know that their renomination is secure, the anticipation to be reselected is undisputed. 

There is concern that a causal-order problem might be underlying our measure of ambition through candidacies. We measure ambition throughout the term via candidacies at the end of the term. We then use this measure to predict efforts in legislative review. It may be that MPs who submit fewer amendments are less likely to be reselected or anticipate that they are less likely to be reselected. In that case their behavior leads to this outcome and the causal order would be reversed. Whether these challenges to our empirical measure are present in the case that we study is an empirical question. We investigate this question in the following and find robust evidence against a causal order problem.

As the re-nominations take place some time in the last year of the legislative term, we restrict our statistical models to bills that were introduced in the last year of the legislative term. In these cases, the renomination decisions have already taken place. For this last period, our measure of political ambition (candidatures) is by definition exogenous to our dependent variable, allowing us to check whether the effects are stable. Figure \ref{fig:order1} visualizes the subsample of bills that this analysis is based on; Table \ref{tab:lastyear} summarizes the re-estimation of models M1-M4. This drastically reduces our sample size which is why the full model including 17 covariates can no longer be estimated. Therefore, we present a model only including the candidacy measure alongside a simplified model. The magnitude and direction of all effects remains the same, with statistically significant results across various models and operationalizations. We interpret this as evidence for our measure of candidacies and against a causal order problem. 

\begin{figure}
    \centering
    \includegraphics{order1.png}
    \caption{Visualization of the subsample for the re-estimation of models M1-M4}
    \label{fig:order1}
\end{figure}

\begin{table}[H]  
\singlespacing
   \caption{Determinants of individual legislative review, last year of legislative term only} 
  \label{tab:lastyear} 
 \begin{center}
\resizebox{\textwidth}{!}{
\begin{tabular}{@{\extracolsep{5pt}}lcccccccc} 
\\[-1.8ex]\hline 
\hline \\[-1.8ex] 
 & \multicolumn{8}{c}{\textit{Dependent variable:}} \\ 
\cline{2-9} 
\\[-1.8ex] & \multicolumn{4}{c}{Bill Amendment} & \multicolumn{4}{c}{Number of Article Changes} \\ 
\\[-1.8ex] & (1a) & (1b) & (2a) & (2b) & (3a) & (3b) & (4a) & (4b)\\ 
\hline \\[-1.8ex] 
\textit{Main Independent Variables} & & & & & & & & \\
 Progressive Ambition & 2.295 & 0.857 &  &  & 3.647 & 1.314 &  &  \\ 
  & (1.865) & (0.954) &  &  & (2.026) & (1.033) &  &  \\ 
 Static Ambition & 0.739 & 0.805$^{*}$ &  &  & 1.193 & 1.075$^{**}$ &  &  \\ 
  & (0.560) & (0.395) &  &  & (0.631) & (0.414) &  &  \\ 
 Social Media Presence &  &  & 0.324 & 0.506$^{*}$ &  &  & 0.225 & 0.261 \\ 
  &  &  & (0.401) & (0.249) &  &  & (0.411) & (0.245) \\ 
  & & & & & & & & \\ 
  \textit{MP-Level Controls} & & & & & & & & \\
 Seniority &  & 0.050$^{**}$ &  & 0.043$^{*}$ &  & 0.037 &  & 0.029 \\ 
  &  & (0.019) &  & (0.019) &  & (0.021) &  & (0.021) \\ 
 First Term &  & $-$0.818$^{*}$ &  & $-$0.880$^{*}$ &  & $-$0.535 &  & $-$0.522 \\ 
  &  & (0.401) &  & (0.401) &  & (0.376) &  & (0.378) \\ 
 Committee Member &  & 2.539$^{***}$ &  & 2.562$^{***}$ &  & 2.228$^{***}$ &  & 2.311$^{***}$ \\ 
  &  & (0.279) &  & (0.279) &  & (0.298) &  & (0.297) \\ 
 Leadership Position &  & 1.139$^{***}$ &  & 1.141$^{***}$ &  & 1.143$^{**}$ &  & 1.202$^{***}$ \\ 
  &  & (0.328) &  & (0.325) &  & (0.358) &  & (0.363) \\ 
 Closeness of Electoral Race &  & 0.081$^{***}$ &  & 0.080$^{***}$ &  & 0.067$^{***}$ &  & 0.069$^{***}$ \\ 
  &  & (0.016) &  & (0.016) &  & (0.016) &  & (0.016) \\ 
  & & & & & & & & \\ 
   \textit{Bill-Level Controls} & & & & & & & & \\
 Log (Party Group Size) &  & $-$0.320 &  & $-$0.366$^{*}$ &  & $-$0.247 &  & $-$0.286 \\ 
  &  & (0.174) &  & (0.174) &  & (0.186) &  & (0.188) \\ 
  & & & & & & & & \\ 
 Opposition Chair Committee &  & 0.489 &  & 0.472 &  & 0.530 &  & 0.500 \\ 
  &  & (0.682) &  & (0.683) &  & (0.694) &  & (0.694) \\ 
  & & & & & & & & \\ 
 Log(Number of Bills in Policy Field) &  & $-$0.116 &  & $-$0.119 &  & $-$0.171 &  & $-$0.178 \\ 
  &  & (0.441) &  & (0.443) &  & (0.447) &  & (0.448) \\ 
  & & & & & & & & \\ 
 Log(Bill Length) &  & 0.862$^{*}$ &  & 0.854$^{*}$ &  & 1.017$^{**}$ &  & 1.017$^{**}$ \\ 
  &  & (0.376) &  & (0.378) &  & (0.383) &  & (0.384) \\ 
  & & & & & & & & \\ 
 Constant & $-$6.676$^{***}$ & $-$8.569$^{***}$ & $-$6.219$^{***}$ & $-$7.840$^{***}$ & $-$10.030$^{***}$ & $-$8.425$^{***}$ & $-$6.120$^{***}$ & $-$7.417$^{***}$ \\ 
  & (0.618) & (2.150) & (0.448) & (2.125) & (1.213) & (2.178) & (0.451) & (2.151) \\ 
  & & & & & & & & \\ 
\hline \\[-1.8ex] 
N (Bills $\times$ MPs) & 5,885 & 5,885 & 5,885 & 5,885 & 5,885 & 5,885 & 5,885 & 5,885 \\ 
N (Bills) & 96 & 96 & 96 & 96  & 96 & 96 & 96 & 96 \\ 
N (MPs) & 121 & 121 & 121 & 121 & 121 & 121 & 121 & 121 \\ 
\hline 
\hline \\[-1.8ex] 
\end{tabular}}
\end{center}
\textit{Note: Table presents unstandardized coefficients from cross-classified multilevel logistic and negative binomial regression models with random intercepts at the bill- and MP-level. Standard errors are reported in parentheses. $^{*}$p$<$0.05; $^{**}$p$<$0.01; $^{***}$p$<$0.001.}
\end{table} 

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