بوردهای بانک مرکزی در سراسر جهان : چرا اندازه عضویت متفاوت است؟

This paper analyzes empirically differences in the size of central bank boards (or monetary policy committees) across countries. We discuss the possible determinants of a board's size. The empirical relevance of these factors is examined using a new dataset that covers the de jure membership size of 84 central bank boards at the end of 2003. We find that larger and more heterogeneous countries, countries with stronger democratic institutions, countries with floating exchange rate regimes, and independent central banks with more staff tend to have larger boards.

Size matters, in particular when it comes to central bank boards or monetary policy committees (MPCs).1 While monetary policy may be a “science,” it is hardly an exact one; it operates in an environment surrounded by considerable uncertainty. As a result, the way MPCs exploit information and agree on decisions may be critical for the quality and success of monetary policy. Current research has particularly emphasized the importance of central bank organization – and especially the size of central bank boards or MPCs – in this regard.2 Specifically, academics and policy makers have recently stressed the advantages of larger MPCs.3 For instance, Blinder (2006) and Blinder and Morgan (2005) argue that multiple decision makers make fewer mistakes and better decisions when information is incomplete—an argument that is loosely based on Condorcet's jury theorem. Gerling et al. (2005) summarize a larger literature from a game theoretic perspective; they argue that larger MPCs are particularly attractive if information is not public in nature. Auriol and Gary-Bobo (2007) note that, in general, true representation of a politically and economically diverse area will require a larger number of representatives. The surveys by Fujiki (2005), Sibert (2006), Vandenbussche (2006), and Berger (2006) provide a comprehensive overview over this rapidly expanding literature.4 As Goodfriend (2005, p. 85) remarks, however, “the efficient size of a policy committee might vary across countries.” Countries differ along various economic, political, and institutional dimensions and (some of) these characteristics may also shape the advantages of larger MPCs. For instance, the argument to increase board size to achieve better information processing appears to be of particular relevance when an economy is large or characterized by considerable diversity across regions and industries. Similarly, a country's political institutions may matter for MPC size, with less democratic regimes perhaps preferring a smaller board (since a large MPC could effectively provide insulation from political pressures).5,6 Finally, MPC size is probably also affected by other elements of central bank design such as the institutional functions performed by a central bank. For instance, if the central bank enjoys full autonomy over both policy targets and instruments, the MPC may be larger than when the central bank's autonomy is more limited. A case in point is the recent discussion of the design of the European Central Bank's (ECB's) 19-member Governing Council, in which there is at least one representative from each member country of the monetary union (see, for instance, Baldwin et al., 2001 and Berger et al., 2004). In light of the ongoing increase in euro area membership, the ECB has limited the (future) number of voting members to 21. Even with this restriction, however, the Council appears to be relatively large; most of the 82 central banks surveyed by Fry et al. (2000) have an MPC with about 5–10 members. It is still unclear, though, whether the ECB Governing Council is indeed exceptionally large or just a manifestation of a general pattern where larger countries tend to endow their central banks with larger MPCs. Despite the considerable interest in MPC size, there is surprisingly little evidence about the cross-country variation in central bank boards and their determinants. Fry et al. (2000) document differences in MPC size across countries but provide no explanations. Erhart and Vasquez-Paz (2007) review a small number of potential determinants of MPC size. However, to the best of our knowledge, a systematic, broad-based empirical analysis of differences in MPC size is missing. In this paper, we aim to fill this void by systematically characterizing differences in the membership size of decision-making bodies of central banks around the world. Since central banks often operate various boards, committees, and councils, we focus on the central bank's implementation board (or MPC) that makes decisions on whether and when to change policy instruments to achieve a given monetary policy target.7 Our results indicate that board size is indeed strongly and plausibly associated with a number of country-specific characteristics. We find, for instance, that board size is related to country size and country heterogeneity as well as to a country's political institutions. Also, MPC size is often associated with other central bank characteristics. The remainder of the paper is organized as follows. In Section 2, we provide a detailed discussion of possible determinants of MPC size. Section 3 presents the data and the empirical results, and Section 4 provides a brief conclusion.

Recent research emphasizes the importance of central bank design for the success of monetary policy. One of the features that have received particular interest is the membership size of the central bank's decision-making body—that is, how many people should decide whether to take measures to achieve a specified monetary policy target? In theory, the membership size of an MPC depends on the costs and benefits of appointing members. On the benefit side, larger MPCs promise improvements in information processing along the lines of Condorcet's jury theorem. At the same time, decision making typically becomes more difficult and time consuming as the number of MPC members increases. Also, members may have a stronger incentive to “freeride” on the information-processing efforts of others in larger MPCs. Since factors affecting the costs and benefits of board size are likely to differ across countries (e.g., the information-processing requirement might vary with the size and diversity of the economy), it seems reasonable to assume that also “the efficient size of a policy committee might vary across countries” (Goodfriend, 2005, p. 85). Around the world, central bank boards do indeed come in different sizes. In New Zealand, for instance, the governor alone is responsible for policy-making, while the European Central Bank (ECB) Governing Council currently comprises 19 members. Moreover, the pending increase in euro area membership has triggered a preemptive ECB reform that generally limits the overall number of voting members to 21. This, however, still seems to be a relatively large number compared with the membership size of other central bank decision-making bodies such as the U.S. Federal Reserve's Federal Open Market Committee. The average MPC in our sample of central banks has 7–9 members. In this paper, we characterize differences in the structure of central bank governance. Our analysis is based on a dataset that covers the (de jure) membership size of 84 central bank boards around the world at the end of 2003 that make decisions on whether to increase or decrease interest rates to achieve a specified target.40 We find that board size is indeed significantly and plausibly correlated to various country and central bank characteristics. For instance, MPC size tends to increase with country size and population heterogeneity, thereby providing empirical support for the notion that information-processing requirements affect central bank board size. There is also evidence that MPC size is correlated to political institutions, with more democratic countries having, on average, larger boards. For some variables, we find a hump-shaped effect on MPC size. Finally, although the size of the central bank's policy committee has been the focus of much debate recently, there are indications that it should not be viewed as independent of other features of central bank design. MPC size is often associated with other central bank characteristics. For instance, central banks tend to have larger MPCs if they have more staff or higher operational expenditure. More importantly, countries with floating exchange rate regimes, which typically have more complicated monetary policy frameworks, also seem to operate larger boards. Along similar lines, we find that more independent central banks often have larger MPCs. Viewed in conjunction with the results discussed previously, this suggests that the institutional setup of central banks may indeed be tailored to reflect country-specific factors.