Detection of outliers in simple circular regression models using the mean circular error statistic

The investigation on the identification of outliers in linear regression models can be extended to those for circular regression case. In this paper, we propose a new numerical statistic called mean circular error to identify possible outliers in circular regression models by using a row deletion approach. Through intensive simulation studies, the cut-off points of the statistic are obtained and its power of performance investigated. It is found that the performance improves as the concentration parameter of circular residuals becomes larger or the sample size becomes smaller. As an illustration, the statistic is applied to a wind direction data set.     

Error catastrophe in mutant mitochondria

The error catastrophe theory of aging, proposed by Orgel in 1963, predicted a decrease in the fidelity of information transfer that accelerated as aging progressed, until properly functioning macromolecules could no longer be reliably made. The theory was extensively tested by comparing DNA polymerases, transfer RNAs, and proteins derived from aging versus young animals, but it did not prove to have general applicability to the process of aging. Recently, the heritable eye disorder progressive external ophthalmoplegia has been found to result from mutation of the gene encoding DNA polymerase gamma, which replicates mitochondrial DNA. The mutant form of the polymerase replicates DNA less accurately than the wild-type enzyme, providing an explanation for the accumulation of mutations in the mitochondrial DNA of patients with this disorder. The affected mitochondria appear to exhibit an age-dependent error catastrophe. It is possible that other genetic diseases might result in error catastrophes in mitochondria as well.     

Political Competence and Mass Media Use

Relationships are examined between feelings of political competenceand cumulative media usage in five Western nations. Wide differentiationamong the nations studied is found, suggesting that multivariateanalysis is needed to establish whether media usage makes aunique contribution to feelings of political competence, oracts as a surrogate for other background variables.     

The influence of macroeconomic variables on the probability of union decertification

This study focuses on the role macroeconomic factors play in explaining the proportion of decertification elections lost by the union movement in the postwar period. Previous research has neglected the importance of such macroeconomic variables. Our results indicate that the union-nonunion wage differential, inflation, strikes, state of the labor market, and union density are related to the phenomenon of decertification. The authors would like to thank Greg Hundley, Mike Bognanno, Paul Schumann, Jim Scoville, the editor, and a reviewer for valuable comments and Michael Wachter and William Wascher for providing some unpublished data.