On optimality of one‐bug‐look‐ahead policies for a software testing model

The optimality of the One‐Bug‐Look‐Ahead (OLA) software release policy proposed by Morali and Soyer ( 15 ) is re‐examined in this paper. A counterexample is constructed to show that OLA is not optimal in general. The optimal stopping approach is then called upon to prove that OLA possesses weaker sense of optimality under conditional monotonicity and the strong sense of optimality holds under a more restrictive sample‐wise monotonicity condition. The NTDS data are analyzed for illustration, and OLA is shown to be robust with respect to model parameters. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007.     

Testing goodness of fit to the increasing failure rate family

One branch of the reliability literature is concerned with devising statistical procedures with various nonparametric “restricted family” model assumptions because of the potential improved operating characteristics of such procedures over totally nonparametric ones. In the single-sample problem with unknown increasing failure rate (IFR) distribution F, (1) maximum-likelihood estimators of F have been calculated, (2) upper or lower tolerance limits for F have been determined, and (3) tests of the null hypothesis that F is exponential have been constructed. Barlow and Campo proposed graphical methods for assessing goodness of fit to the IFR model when the validity of this assumption is unknown. This article proposes several analytic tests of the IFR null hypothesis based on the maximum distance and area between the cumulative hazard function and its greatest convex minorant (GCM), and the maximum distance and area between the total time on test statistic and its GCM. A table of critical points is provided to implement a specific test having good overall power properties.     

Testing goodness of fit to the increasing failure rate family with censored data

One important thrust in the reliability literature is the development of statistical procedures under various “restricted family” model assumptions such as the increasing failure rate (IFR) and decreasing failure rate (DFR) distributions. However, relatively little work has been done on the problem of testing fit to such families as a null hypothesis. Barlow and Campo proposed graphical methods for assessing goodness of fit to the IFR model in single-sample problems. For the same problem with complete data, Tenga and Santner studied several analytic tests of the null hypothesis that the common underlying distribution is IFR versus the alternative that it is not IFR for complete data. This article considers the same problem for the case of four types of censored data: (i) Type I (time) censoring, (ii) Type I1 (order statistic) censoring, (iii) a hybrid of Type I and Type I1 censoring, and (iv) random censorship. The least favorable distributions of several intuitive test statistics are derived for each of the four types of censoring so that valid small-sample-size α tests can be constructed from them. Properties of these tests are investigated.     

Naw Bahar District 2010–11: A case study of counterinsurgency Conducted by Naval Special Warfare in Afghanistan

This article provides a critical analysis of counterinsurgency in Afghanistan at the tactical level. The efforts of several Naval Special Warfare detachments deployed to Naw Bahar district in Zabul Province, Afghanistan are examined in detail to identify key successes and failures in planning and execution. It defines the operating environment in which the detachments worked and identifies the goals and outcomes of the first and second phases of the counterinsurgency effort. The article concludes by placing the tactical effort in the context of the overall strategy in Afghanistan and suggests that time is the limiting factor to success.     

Stopping Suicide Attacks: Optimal Strategies and Unintended Consequences

We study the behavior of defense spending in Switzerland over 1975–2001. Our main interest is in determining how neutrality in international affairs (non‐membership in military alliances) affects defense spending. We find that neutrality is associated with a perception of lower levels of external threat; hence it confers economic benefits in the form of a smaller defense burden. However, neutrality does not fully insulate a country from variations in the level of external threat in the global system as perceived by members of military alliances. Swiss defense spending has tracked very closely the spending trends – but at a lower average level – of the United States and other NATO countries. To the extent that post‐Cold War threats, such as international terrorism, materialize primarily in the context of existing security alliances, Swiss military spending patterns observed in 1975–2001 are likely to remain the same in the future.     

Causal Linkages Between Domestic Terrorism and Economic Growth

We use the Hsiao–Granger method to test for terrorism–growth causality for seven Western European countries. In bivariate settings, the impact of economic performance on domestic terrorism is very strong. In trivariate settings, the impact of performance on terrorism diminishes. In general, we find that economic performance leads terrorist violence in robust ways only for three out of seven countries. Terrorism is almost never found to causally influence growth in bivariate and trivariate specifications. Our findings indicate that the role of economic performance in determining terrorist violence appears to have been important for some countries, whereas all attacked economies have been successful in adjusting to the threat of terrorism.     

Book review

Steven L. Burg and Paul S. Shoup, The War in Bosnia‐Herzegovina: Ethnic Conflict and International Intervention.New York: M.E. Sharpe, 1999. Pp.xviii + 499, maps, tables, notes, biobliog., index. NP. ISBN 1–56324–308–3.     

Winning hearts and minds in the ‘war on terrorism’

Ten days after the attacks on the World Trade Center and Pentagon US President George W Bush addressed a joint session of Congress. In an emotional speech he declared war on terrorism and vowed that the US would not rest until all of the perpetrators were brought to justice and A1 Qaeda destroyed. In virtually the next breath he hastened to add that the US-led campaign would not be a war on Islam, a promise Muslims might have found more reassuring had the President not sounded so much like a Baptist preacher. Whatever its propaganda value, the speech distorted the reality of the struggle facing the West while tacitly acknowledging an important truth. Since terror is merely a weapon in a larger struggle, there can be no war on terrorism per se. The West faces a counterinsurgency campaign on a global scale. Winning the hearts and minds of disaffected people in lands where terrorism thrives must be central to conducting this campaign.