¹ Throughout this article, the term ‘mediation’ (mediate) and ‘intervention’ (intervene) are used interchangeably.

² See, for example, Bercovitch, Jacob, Theodore Anagnoson, J. and Wille, Donnette L., ‘Some Conceptual Issues and Empirical Trends in the Study of Successful Mediation in International Relations’, Journal of Peace Research, 28 (1991), 7–17CrossRefGoogle Scholar; Bercovitch, Jacob and Schneider, Gerald, ‘Who Mediates? The Political Economy of International Conflict Management’, Journal of Peace Research, 37 (2000), 145–165CrossRefGoogle Scholar; Gent, Stephen E. and Shannon, Megan, ‘It's Not Who but How: Third Parties and the Peaceful Settlement of Territorial Claims’ (paper prepared for the Annual Meeting of the American Political Science Association, Chicago, 2007)Google Scholar.

³ Crocker, Chester A., Hampson, Fen O. and Aall, Pamela, eds, Herding Cats: Multiparty Mediation in a Complex World (Washington, D.C.: USIP, 1999), p. 9Google Scholar; see also Crocker, Chester A., Hampson, Fen O. and Aall, Pamela, ‘Is More Better? The Pros and Cons of Multiparty Mediation’, in Chester A. Crocker, Fen O. Hampson and Pamela Aall, eds, Turbulent Peace: The Challenges of Managing International Conflict (Washington, D.C.: USIP, 2001)Google Scholar.

⁴ See Aydin, Aysegul and Regan, Patrick, ‘Networks of Third-Party Interveners and Civil War Duration’ (unpublished paper, available from the authors, 2010), p. 2Google Scholar.

⁵ Crocker, Chester A., Hampson, Fen Osler and Aall, Pamela, ‘A Crowded Stage: Liabilities and Benefits of Multiparty Mediation’, International Studies Perspectives, 2 (2001), 51–67CrossRefGoogle Scholar.

⁶ Ki-Moon, Ban, Report of the Secretary-General on Enhancing Mediation and its Support Activities (New York: United Nations Security Council, Document S/2009/189, 2009)Google Scholar.

⁷ Beardsley, Kyle and Michael Greig, J., ‘Disaggregating the Incentives of Conflict Management: An Introduction’, International Interactions, 35 (2009), 243–248CrossRefGoogle Scholar, p. 247.

⁸ See Crocker, Hampson and Aall, Herding Cats; Crocker, Hampson and Aall, ‘Is More Better?’ Greig, Michael J. and Diehl, Paul F., ‘Softening Up: Making Conflicts More Amenable to Diplomacy’, International Interactions, 32 (2006), 355–384CrossRefGoogle Scholar, pp. 363ff.; Kydd, Andrew, ‘When Can Mediators Build Trust?’ American Political Science Review, 100 (2006), 449–462CrossRefGoogle Scholar, pp. 450f.

⁹ Buchanan, James M. and Tullock, Gordon, The Calculus of Consent: Logical Foundations of Constitutional Democracy (Ann Arbor: University of Michigan Press, 1962)CrossRefGoogle Scholar; Snidal, Duncan, ‘The Politics of Scope: Endogenous Actors, Heterogeneity, and Institutions’, Journal of Theoretical Politics, 6 (1994), 449–472CrossRefGoogle Scholar; see also Olson, Mancur Jr, The Logic of Collective Action – Public Goods and the Theory of Groups (Cambridge, Mass.: Harvard University Press, 1965)Google Scholar.

¹⁰ See Axelrod, Robert and Keohane, Robert O., ‘Achieving Cooperation under Anarchy: Strategies and Institutions’, World Politics, 38 (1985), 226–254CrossRefGoogle Scholar; Crescenzi, Mark J. and Enterline, Andrew J., ‘Time Remembered: A Dynamic Model of Interstate Interaction’, International Studies Quarterly, 45 (2001), 409–431CrossRefGoogle Scholar; Crescenzi, Mark J., Enterline, Andrew J. and Long, Stephen B., ‘Bringing Cooperation Back In: A Dynamic Model of Interstate Interaction’, Conflict Management and Peace Science, 25 (2008), 264–280CrossRefGoogle Scholar; Keohane, Robert O., After Hegemony: Cooperation and Discord in the World Political Economy (Princeton, N.J.: Princeton University Press, 1984)Google Scholar.

¹¹ See Dixon, William J., ‘Democracy and the Peaceful Settlement of International Conflict’, American Political Science Review, 88 (1994), 14–32CrossRefGoogle Scholar; Raymond, Gregory A., ‘Democracies, Disputes, and Third-Party Intermediaries’, Journal of Conflict Resolution, 38 (1994), 24–42CrossRefGoogle Scholar; Bercovitch, Jacob and Houston, Allison, ‘Why Do They Do It Like This? An Analysis of the Factors Influencing Mediation Behavior in International Conflicts’, Journal of Conflict Resolution, 44 (2000), 170–202CrossRefGoogle Scholar; McLaughlin Mitchell, Sara, ‘A Kantian System? Democracy and Third-Party Conflict Resolution’, American Journal of Political Science, 46 (2002), 749–759CrossRefGoogle Scholar.

¹² Hensel, Paul R. and Mitchell, Sara McLaughlin, Issues Correlates of War Project: User Manual for ICOW Data, Version 1.1 (available at http://www.icow.org, 2007)Google Scholar; see also Hensel, Paul R., ‘Contentious Issues and World Politics: The Management of Territorial Claims in the Americas, 1816–1992’, International Studies Quarterly, 45 (2001), 81–109CrossRefGoogle Scholar; Hensel, Paul R., Sara McLaughlin, Mitchell, Sowers, Thomas E. and Thyne, Clayton L., ‘Bones of Contention: Comparing Territorial, Maritime, and River Issues’, Journal of Conflict Resolution, 52 (2008), 117–143CrossRefGoogle Scholar.

¹³ Crocker, Hampson and Aall, Herding Cats; Crocker, Hampson and Aall, ‘Is More Better?’; see also Nan, Susan A. and Strimling, Andrea, ‘Coordination in Conflict Prevention, Conflict Resolution and Peacebuilding’, International Negotiation, 11 (2006), 1–6CrossRefGoogle Scholar.

¹⁴ See Nan, Susan A., ‘Track I Diplomacy’, in Guy Burgess and Heidi Burgess, eds, Beyond Intractability. (Boulder, Colo.: Conflict Research Consortium, University of Colorado, 2003)Google Scholar.

¹⁵ Crocker, Hampson and Aall, Herding Cats; Crocker, Hampson and Aall, ‘Is More Better?’; Crocker, Hampson and Aall, ‘A Crowded Stage’. For a detailed overview about the potential benefits and costs of multiparty mediation, see also Beber, Bernd, ‘The (Non-) Efficacy of Multi-Party Mediation in Wars Since 1990’ (unpublished paper, available from the author, 2010)Google Scholar.

¹⁶ Crocker, , Hampson, and Aall, , Herding Cats, p. 210Google Scholar; Crocker, Hampson and Aall, ‘Is More Better?’

¹⁷ The other two categories are of minor theoretical importance and I leave their examination to future research. Still, the data I use for the succeeding empirical analysis comprise cases of these two categories as well, and although I do not specifically address them in my research, controlling for these influences does not seem to have any substantial effect. Furthermore, in the following, I only focus on states’ multiparty mediation due to the limited availability of data and the fact that states remain ‘the most successful and enduring forms of social and political organization’ (Bercovitch and Schneider, ‘Who Mediates?’ p. 147).

¹⁸ Crocker, Hampson and Aall, ‘A Crowded Stage’, p. 59.

¹⁹ Crocker, , Hampson, and Aall, , Herding Cats, p. 230Google Scholar.

²⁰ Crocker, , Hampson, and Aall, , ‘A Crowded Stage’, p. 63Google Scholar.

²¹ Crocker, , Hampson, and Aall, , Herding Cats, p. 22Google Scholar.

²² Crocker, , Hampson, and Aall, , Herding Cats, pp. 33Google Scholar, 38f.

²³ Garb, Paula and Nan, Susan A., ‘Negotiating in a Coordination Network of Citizen Peacebuilding Initiatives in the Georgian-Abkhaz Peace Process’, International Negotiation, 11 (2006), 7–35CrossRefGoogle Scholar.

²⁴ Strimling, Andrea, ‘Stepping Out of the Tracks: Cooperation between Official Diplomats and Private Facilitators’, International Negotiation, 11 (2006), 91–127, p. 94CrossRefGoogle Scholar; see also Kelman, Herbert C., ‘The Role of an International Facilitating Service for Conflict Resolution’, International Negotiation, 11 (2006), 209–223CrossRefGoogle Scholar.

²⁵ Strimling, , ‘Stepping Out of the Tracks’, p. 92Google Scholar.

²⁶ Crocker, Hampson and Aall, Herding Cats; see also Crocker, Hampson and Aall, ‘Is More Better?’.

²⁷ Crocker, , Hampson, and Aall, , Herding Cats, pp. 39fGoogle Scholar.

²⁸ Crocker, , Hampson, and Aall, , ‘Is More Better?’, p. 507Google Scholar.

²⁹ See, for example, Crocker, , Hampson, and Aall, , Herding Cats, p. 22; Crocker, Hampson and Aall, ‘Is More Better?’; Greig and Diehl, ‘Softening Up’, pp. 363f; Kydd, ‘When Can Mediators Build Trust?’, pp. 450fGoogle Scholar.

³⁰ Touval, Saadia and Zartman, William I., eds, International Mediation in Theory and Practice (Boulder, Colo.: Westview Press, 1985), at p. 40Google Scholar.

³¹ See Frazier, Derrick and Dixon, William, ‘Third-Party Intermediaries and Negotiated Settlements, 1946–2000’, International Interactions, 32 (2006), 385–408CrossRefGoogle Scholar, pp. 391ff; Kaye, Dalia, ‘Track Two Diplomacy and Regional Security in the Middle East’, International Negotiation, 6 (2001), 49–77CrossRefGoogle Scholar, p. 64.

³² Crocker, , Hampson, and Aall, , Herding Cats, p. 40Google Scholar.

³³ See Buchanan and Tullock, The Calculus of Consent; Olson, The Logic of Collective Action, pp. 46ff; Chamberlain, John, ‘Provision of Collective Goods as a Function of Group Size’, American Political Science Review, 68 (1974), 707–716CrossRefGoogle Scholar.

³⁴ Snidal, ‘The Politics of Scope’.

³⁵ Beardsley, Kyle, ‘Pain Pressure and Political Cover: Explaining Mediation Incidence’, Journal of Peace Research, 47 (2010), 395–406CrossRefGoogle Scholar.

³⁶ Fearon, James D., ‘Bargaining, Enforcement, and International Cooperation’. International Organization, 52 (1998), 269–306CrossRefGoogle Scholar, p. 270; see also Crocker, Hampson and Aall, ‘A Crowded Stage’.

³⁷ Axelrod, and Keohane, , ‘Achieving Cooperation under Anarchy’, p. 235Google Scholar; North, Douglass, Institutions, Institutional Change and Economic Performance (Cambridge: Cambridge University Press, 1990), p 57CrossRefGoogle Scholar; Olson, , The Logic of Collective Action, pp. 45fGoogle Scholar.

³⁸ See Axelrod and Keohane, ‘Achieving Cooperation under Anarchy’, pp. 234ff; Frohlich, Norman and Oppenheimer, Joe A., ‘I Get by with a Little Help from my Friends’, World Politics, 23 (1970), 104–120CrossRefGoogle Scholar; North, Institutions, Institutional Change and Economic Performance, p. 57; Olson, The Logic of Collective Action, p. 36.

³⁹ See also Buchanan and Tullock, The Calculus of Consent.

⁴⁰ See Crescenzi and Enterline, ‘Time Remembered’. See also Aydin and Regan, Networks of Third-Party Interveners and Civil War Duration.

⁴¹ Crescenzi and Enterline, ‘Time Remembered’. See also Goertz, Gary and Diehl, Paul F., ‘Enduring Rivalries: Theoretical Constructs and Empirical Patterns’, International Studies Quarterly, 37 (1993), 147–171CrossRefGoogle Scholar, pp. 159f.

⁴² Crescenzi, and Enterline, , ‘Time Remembered’, p. 410Google Scholar.

⁴³ Garb and Nan, ‘Negotiating in a Coordination Network of Citizen Peacebuilding Initiatives in the Georgian-Abkhaz Peace Process’.

⁴⁴ Kelman, ‘The Role of an International Facilitating Service for Conflict Resolution’.

⁴⁵ See Keohane, After Hegemony; Axelrod and Keohane, ‘Achieving Cooperation under Anarchy’.

⁴⁶ For example, Oneal, John R. and Russett, Bruce, ‘The Kantian Peace: The Pacific Benefits of Democracy, Interdependence, and International Organizations, 1885–1992’, World Politics, 52 (1999), 1–37CrossRefGoogle Scholar. See also Leng, Russell J. and Regan, Patrick M., ‘Social and Political Cultural Effects on the Outcomes of Mediation in Militarized Interstate Disputes’, International Studies Quarterly, 47 (2003), 431–452CrossRefGoogle Scholar.

⁴⁷ For example, Dixon, ‘Democracy and the Peaceful Settlement of International Conflict’; Raymond, ‘Democracies, Disputes, and Third-Party Intermediaries’; Bercovitch and Houston, ‘Why Do They Do It Like This?’ Mitchell, ‘A Kantian System?’. Note that autocracies also share a common structural background, although they certainly lack the thereby induced shared norm of peaceful conflict settlement.

⁴⁸ Dixon, ‘Democracy and the Peaceful Settlement of International Conflict’.

⁴⁹ Simmons, Beth A., ‘See You in ‘Court’? The Appeal to Quasi-Judicial Legal Processes in the Settlement of Territorial Disputes’ in Paul F. Diehl, ed., A Roadmap to War: Territorial Dimensions of International Conflict (Nashville, Tenn.: Vanderbilt University Press, 1999), pp. 205–237Google Scholar.

⁵⁰ McLaughlin Mitchell, Sara, Kadera, Kelly M. and Crescenzi, Mark J., ‘Practicing Democratic Community Norms: Third Party Conflict Management and Successful Settlements’, in Jacob Bercovitch and Scott Sigmund Gartner, eds, Empirical Studies in International Mediation (New York: Routledge, 2005), p. 8Google Scholar.

⁵¹ Dorussen, Han and Ward, Hugh, ‘Inter Governmental Organizations and the Kantian Peace – A Network Perspective’, Journal of Conflict Resolution, 52 (2008), 189–212CrossRefGoogle Scholar, p. 193.

⁵² Crescenzi, Mark J., Kadera, Kelly M., Mitchell, Sara McLaughlin and Thyne, Clayton L., ‘A Supply Side Theory of Mediation’ (forthcoming in International Studies Quarterly, but available from www.unc.edu/home/crescenz/publications), p. 13Google Scholar.

⁵³ Olson, Mancur, ‘Dictatorship, Democracy, and Development’, American Political Science Review, 87 (1993), 567–576CrossRefGoogle Scholar, p. 571.

⁵⁴ Choi, Ajin, ‘The Power of Democratic Cooperation’, International Security, 28 (2003), 142–153CrossRefGoogle Scholar, p. 145.

⁵⁵ Keohane, Robert O., ‘The Demand of International Regimes’, in Stephen D. Krasner, ed., International Regime (Ithaca, N.Y.: Cornell University Press, 1983), pp. 162–163Google Scholar.

⁵⁶ Strimling, ‘Stepping Out of the Tracks’.

⁵⁷ Touval and Zartman, eds, International Mediation in Theory and Practice; see also Bercovitch, Anagnoson and Wille, ‘Some Conceptual Issues and Empirical Trends in the Study of Successful Mediation in International Relations’. I have paraphrased Touval and Zartman to present the broadest possible definition of mediation.

⁵⁸ Note, however, that this approach only excludes direct or ‘pure’ military interventions. If conflicts comprise both military interventions and third-party mediations, for example, I do consider these settlement attempts in my analysis.

⁵⁹ Hensel and Mitchell, Issues Correlates of War Project; see also Hensel, ‘Contentious Issues and World Politics’; Hensel, Mitchell, Sowers and Thyne, ‘Bones of Contention’. The advantages of the ICOW data are twofold. First, they allow comparison across various issues of contention. Secondly, since the data's cases are not constrained to situations that become militarized at some point, we are able to circumvent the problem of selection bias to some extent.

⁶⁰ Crescenzi and Enterline, ‘Time Remembered’; see also Crescenzi, Enterline and Long, ‘Bringing Cooperation Back In’; note that there are also alternative operationalizations for conflicting and co-operative relationships. Previous studies, for example, rely on the similarity of alliance portfolios as measured by Kendall's τ_b ( de Mesquita, Bruce Bueno, ‘Systematic Polarization and the Occurrence and Duration of War’, Journal of Conflict Resolution, 22 (1978), 241–267CrossRefGoogle Scholar; de Mesquita, Bruce Bueno, The War Trap (New Haven, Conn.: Yale University Press, 1981)Google Scholar or the S-score ( Signorino, Curtis S. and Ritter, Jeffrey M., ‘Tau-b or not Tau-b: Measuring the Similarity of Foreign Policy Positions’, International Studies Quarterly, 43 (1999), 115–144CrossRefGoogle Scholar). With regard to the former, however, I believe that this item it theoretically too far from my claimed mechanism, since τ_b essentially measures states’ associations via alliances. With regard to the latter, Bennett, D. Scott and Rupert, Matthew C. (‘Comparing Measures of Political Similarity: An Empirical Comparison of S versus τ_b in the Study of International Conflict’, Journal of Conflict Resolution, 47 (2003), 367–393Google Scholar) demonstrate that the S-score suffers from measurement errors and is artificially skewed towards higher dyadic similarity. In other words, although Crescenzi and Enterline's (‘Time Remembered’) dynamic model of interstate interaction is the primary reason for my constrained temporal domain, the potential bias and measurement error is likely to be lower.

⁶¹ See Crescenzi, Enterline and Long, ‘Bringing Cooperation Back In’.

⁶² Crescenzi, Enterline and Long (‘Bringing Cooperation Back In’) emphasize that the form of this function constantly drives the value of i_td towards zero over time; also, the exponential decay is accelerated by increases in Event Temporal Dist, but decelerated by increases in Event History.

⁶³ Crescenzi and Enterline, ‘Time Remembered’.

⁶⁴ Pevehouse, Jon, Nordstrom, Timothy and Warnke, Kevin, ‘The Correlates of War 2 International Governmental Organizations Data Version 2.0’, Conflict Management and Peace Science, 21 (2004), 101–119CrossRefGoogle Scholar; Crescenzi, Enterline and Long, ‘Bringing Cooperation Back In’.

⁶⁵ Marshall, Monty G. and Jaggers, Keith, POLITY IV Project: Political Regime Characteristics and Transitions, 1800–2002. Dataset User's Manual (College Park: University of Maryland, 2002)Google Scholar.

⁶⁶ Bercovitch, Jacob and Langley, Jeffrey, ‘The Nature of the Dispute and the Effectiveness of International Mediation’, Journal of Conflict Resolution, 37 (1993), 670–691CrossRefGoogle Scholar; Kleiboer, Marieke, ‘Understanding Success and Failure of International Mediation’, Journal of Conflict Resolution, 40 (1996), 360–389CrossRefGoogle Scholar.

⁶⁷ For example, Dixon, ‘Democracy and the Peaceful Settlement of International Conflict’; Raymond, ‘Democracies, Disputes, and Third-Party Intermediaries’; Bercovitch and Houston, ‘Why Do They Do It Like This?’ Mitchell, ‘A Kantian System?’.

⁶⁸ Marshall and Jaggers, POLITY IV Project.

⁶⁹ Bennett, D. Scott and Stam, Allan C., ‘The Duration of Interstate Wars, 1816–1985’, American Political Science Review, 90 (1996), 1260–1288CrossRefGoogle Scholar; Mason, David T. and Fett, Patrick J., ‘How Civil Wars End: A Rational Choice Approach’, Journal of Conflict Resolution, 40 (1996), 546–568CrossRefGoogle Scholar, p. 550.

⁷⁰ Singer, David, ‘Reconstructing the Correlates of War Dataset on Material Capabilities of States, 1816–1985’, International Interactions, 14 (1988), 115–132CrossRefGoogle Scholar.

⁷¹ Singer, David, Bremer, Stuart and Stuckey, John, ‘Capability Distribution, Uncertainty, and Major Power War, 1820–1965’, in Bruce Russett, ed., Peace, War, and Numbers (Beverly Hills, Calif.: Sage, 1972)Google Scholar.

⁷² Hensel, ‘Contentious Issues and World Politics’; see Hensel, Mitchell, Sowers and Thyne, ‘Bones of Contention’. See also Bercovitch, Jacob and Gartner, Scott S., ‘Is There Method in the Madness of Mediation? Some Lessons for Mediators from Quantitative Studies of Mediation’, International Interactions, 32 (2006), 329–354CrossRefGoogle Scholar; Quinn, David, Wilkenfeld, Jonathan, Smarick, Kathleen and Asal, Victor, ‘Power Play: Mediation in Symmetric and Asymmetric International Crises’, International Interactions, 32 (2006), 442–470CrossRefGoogle Scholar, p. 454.

⁷³ Hensel, and Mitchell, , Issues Correlates of War Project, p. 5Google Scholar.

⁷⁴ Bercovitch and Langley, ‘The Nature of the Dispute and the Effectiveness of International Mediation’; Kleiboer, ‘Understanding Success and Failure of International Mediation’, pp. 362f.

⁷⁵ Touval and Zartman, eds, International Mediation in Theory and Practice.

⁷⁶ For example, Bercovitch and Gartner, ‘Is There Method in the Madness of Mediation?’ Quinn, Wilkenfeld, Smarick and Asal, ‘Power Play’; Kleiboer, ‘Understanding Success and Failure of International Mediation’. Despite the huge consistence, however, one critical difference between my models and the existing ones in the literature is that the latter usually examine mediations of only violent conflicts, while the ICOW data also include many low-intensity disputes that never turn violent. My inferences could be influenced by this coding decision and I thank an anonymous reviewer for highlighting this to me.

⁷⁷ This result is, for example, mainly consistent with Gent and Shannon, It's Not Who but How: Third Parties and the Peaceful Settlement of Territorial Claims, pp. 18ff.

⁷⁸ Crocker, Hampson and Aall, ‘Is More Better?’.

⁷⁹ Gent, Stephen and Shannon, Megan, ‘The Effectiveness of International Arbitration and Adjudication: Getting Into a Bind’, Journal of Politics, 72 (2010), 366–380CrossRefGoogle Scholar. In this context, Kydd ( Kydd, Andrew, ‘Which Side are You On? Bias, Credibility, and Mediation’, American Journal of Political Science, 47 (2003), 597–611CrossRefGoogle Scholar) argues that a mediator must be biased towards a belligerent if it is to communicate with it honestly. Rauchhaus ( Rauchhaus, Robert W., ‘Asymmetric Information, Mediation, and Conflict Management’, World Politics, 58 (2006), 207–241CrossRefGoogle Scholar) obtains evidence that although biased mediators may be effective, impartial mediators are even more so. In a subsequent paper, Kydd (‘When Can Mediators Build Trust?’) discovers that if a mediator is to help resolve a conflict caused by mutual mistrust, it must be unbiased. However, Savun's results (Burcu Savun, ‘Information, Bias, and Mediation Success’, International Studies Quarterly, 52 (2008), 25–47) suggest that biased mediators and interveners with relevant information yield more effective mediation outcomes. Due to the ambiguity of both theory and empirical evidence and since my explanation is of a rather ad-hoc nature, I leave this issue and a more thorough investigation of it to further research.

⁸⁰ Choukri-Fishere, Ezzedine, Against Conventional Wisdom: Mediating the Arab-Israeli Conflict (Oslo: Centre for Humanitarian Dialogue, 2008)Google Scholar.

⁸¹ Gent, Stephen E., ‘Strange Bedfellows: The Strategic Dynamics of Major Power Military Interventions’, Journal of Politics, 69 (2007), 1089–1102CrossRefGoogle Scholar.

⁸² See Beardsley, ‘Pain Pressure and Political Cover: Explaining Mediation Incidence’.

⁸³ Princen, Thomas, Intermediaries in International Conflict (Princeton, N.J.: Princeton University Press, 1992)Google Scholar; Young, Oran R., ‘Intermediaries: Additional Thoughts on Third-Parties’, Journal of Conflict Resolution, 16 (1972), 51–65CrossRefGoogle Scholar.

⁸⁴ Carolina Garriga, Ana, ‘Regime Type and Bilateral Treaty Formalization: Too Many Cooks Spoil the Soup?’ Journal of Conflict Resolution, 53 (2009), 698–726CrossRefGoogle Scholar.

⁸⁵ Beardsley, ‘Pain Pressure and Political Cover: Explaining Mediation Incidence’; Crocker, Hampson and Aall, ‘A Crowded Stage’, p. 58; see also Gent, ‘Strange Bedfellows’.

⁸⁶ Desch, Michael C., ‘Democracy and Victory: Why Regime Type Hardly Matters’, International Security, 27 (2002), 5–47CrossRefGoogle Scholar; see also Olson, Mancur Jr and Zeckhauser, Richard, ‘An Economic Theory of Alliances’, in Julian R. Friedman, Christopher Bladen and Steven Rosen, eds, Alliance in International Politics (Boston, Mass.: Allyn and Bacon, 1970)Google Scholar.

⁸⁷ See also Beber, , ‘The (Non-)Efficacy of Multi-Party Mediation in Wars Since 1990’, p. 18Google Scholar.

⁸⁸ Leng, Russell J., ‘Reciprocity in Recurring Crises’, International Negotiation, 3 (1998), 197–226CrossRefGoogle Scholar; Greig, Michael and Regan, Patrick M., ‘When Do They Say Yes? An Analysis of the Willingness to Offer and Accept Mediation in Civil Wars’, International Studies Quarterly, 52 (2008), 759–781CrossRefGoogle Scholar.

⁸⁹ Hensel, ‘Contentious Issues and World Politics’; Hensel, Mitchell, Sowers and Thyne, ‘Bones of Contention’.

⁹⁰ Dixon, William J., ‘Third-Party Techniques for Preventing Conflict Escalation and Promoting Peaceful Settlement’, International Organization, 50 (1996), 653–681CrossRefGoogle Scholar.

⁹¹ Favretto, Katja, ‘Should Peacemakers Take Sides? Major Power Mediation, Coercion, and Bias’, American Political Science Review, 103 (2009), 248–263CrossRefGoogle Scholar.

⁹² Singer, Bremer and Stuckey, ‘Capability Distribution, Uncertainty, and Major Power War, 1820–1965’.

⁹³ Böhmelt, Tobias, ‘The Effectiveness of Tracks of Diplomacy Strategies in Third-Party Interventions’, Journal of Peace Research, 47 (2010), 167–178CrossRefGoogle Scholar.

⁹⁴ Heckman, James, ‘Sample Selection Bias as a Specification Error’, Econometrica, 47 (1979), 153–161CrossRefGoogle Scholar.

⁹⁵ I replaced the duration item by a mediation-years variable and different sets of cubic splines. See Beck, Nathaniel, Katz, Jonathan N. and Tucker, Richard, ‘Taking Time Seriously: Time-Series Cross Section Analysis with a Binary Dependent Variable’, American Journal of Political Science, 42 (1998), 1260–1288CrossRefGoogle Scholar.

⁹⁶ This is consistent with, e.g., Beber, ‘The (Non-)Efficacy of Multi-Party Mediation on Wars Since 1990’, p. 20.

⁹⁷ A caveat here is that six countries comprise the maximum size of an intervening coalition in the ICOW data.