Certifying the restricted isometry property is hard

This paper is concerned with an important matrix condition in compressed sensing known as the restricted isometry property (RIP). We demonstrate that testing whether a matrix satisfies RIP is NP-hard. As a consequence of our result, it is impossible to efficiently test for RIP provided P \neq NP

Merger activity and unemployment in the USA

This article presents estimates of the effect of merger activity on the unemployment rate in the US economy using time-series data from 1895 to 1992. Utilizing the methodology suggested by Wickens and Breusch (Economic Journal, Supplement, 189-205, 1988), both the short-run and long-run impacts are estimated. The estimated results suggest that merger activity had a significant negative effect on the unemployment rate in the long run. Even in the short run, merger activity, at the margin, has helped to reduce the unemployment rate.

More on testing the normality assumptionin the Tobit Model

In a recent volume of this journal, Holden [Testing the normality assumption in the Tobit Model, J. Appl. Stat. 31 (2004) pp. 521-532] presents Monte Carlo evidence comparing several tests for departures from normality in the Tobit Model. This study adds to the work of Holden by considering another test, and several information criteria, for detecting departures from normality in the Tobit Model. The test given here is a modified likelihood ratio statistic based on a partially adaptive estimator of the Censored Regression Model using the approach of Caudill [A partially adaptive estimator for the Censored Regression Model based on a mixture of normal distributions, Working Paper, Department of Economics, Auburn University, 2007]. The information criteria examined include the Akaike's Information Criterion (AIC), the Consistent AIC (CAIC), the Bayesian information criterion (BIC), and the Akaike's BIC (ABIC). In terms of fewest 'rejections' of a true null, the best performance is exhibited by the CAIC and the BIC, although, like some of the statistics examined by Holden, there are computational difficulties with each.Censored Regression Model, departures from normality,

Toddler economicus: childhood habit cessation in a Beckerian Model of pacifier use

As a test of elements of Gary Becker's model of habitual behaviours, the present study examines another potential example of a habit - pacifier use - within the youngest segment of the population, infants and toddlers. To explore the facets of a child's pacifier habit, we make use of an extensive questionnaire on the effectiveness of several proposed methods for stopping a child's pacifier consumption. Results indicate that children's pacifier use approaches the habit/addiction threshold, and it is best alleviated with abrupt cessation, or 'cold turkey.' Interestingly, our empirical finding that 'cold turkey' dominates or is superior to other methods of getting children to stop relying on pacifier use (e.g. limiting time of use, altering the pacifier's tip, etc.) has two implications. First, it supports the Beckerian notion that a child's pacifier habit approaches the habit/addiction threshold, as stated above. Second, it contradicts suggestions from many in the health profession to seek methods other than 'cold turkey' to stop a child's pacifier use.

Relation of early career performance and recognition to the probability of winning the Nobel Prize in economics

© 2017, Akadémiai Kiadó, Budapest, Hungary. To explore the relation between early career performance or recognition and receiving the Nobel Prize in Economic Sciences, we compare winners of the John Bates Clark Medal, the most prestigious early career recognition for economists, with other successful scholars. The initial comparison combines JBCM winners with scholars published in leading economics journals, controlling for educational background (institution conferring the Ph.D.) and publication and citation success. We then narrow the comparison group down to those given relatively early recognition (based on age category) in the form of other major awards. Lastly, we compare the JBCM awardees with synthetic counterfactuals that best resemble their pre-award academic career performance. All three analyses provide strong support for the notion that winning the JBCM is related to receiving the Nobel Prize, the award of which is also correlated with early career performance success as measured by number of publications and citations

Touchdowns and test scores: exploring the relationship between athletics and academics

This article examines the relationship between college football success and SAT scores using an updated data series on football winning percentages. The finding here of a positive and significant relationship supports the idea that collegiate athletics, namely football, serves the institution's admissions process. Selective institutions are able to enhance the quality of their student populations. The spinoff benefit of winning teams is such a well-known phenomenon among university administrators that they even have a name for it - 'the Flutie factor,' for the 33 percent increase in applications that Doug Flutie helped bring Boston College when he was a football star there in the early 1980s. (Allen, 1999: 2)