The Powers of Australian Teachers in the Political System of School Government

The views of a sample of Australian teachers were obtained regarding the powers exercised by teachers and administrators in decisions relevant to internal school government. The teachers perceived themselves as playing a delegated-leadership role within the classroom and a subordinate role in decision areas external to classroom management. On the other hand, they expressed a desire to extend their delegated-leadership role to important matters concerning the instructional organization and administration of the school. The evidence suggested that teachers wished to change the perceived balance of power in schools in the direction of a more ‘democratic’ style of school government.     

Easy-to-construct confidence bands for comparing two simple linear regression lines

This paper shows how to construct confidence bands for the difference between two simple linear regression lines. These confidence bands provide directly the information on the magnitude of the difference between the regression lines over an interval of interest and, as a by-product, can be used as a formal test of the difference between the two regression lines. Various different shapes of confidence bands are illustrated, and particular attention is paid towards confidence bands whose construction only involves critical points from standard distributions so that they are consequently easy to construct.     

On the power of durbin-watson statistic against fractionally integrated processes

This paper provides the theoretical explanation and Monte Carlo experiments of using a modified version of Durbin-Watson ( D W ) statistic to test an 1 ( 1 ) process against I ( d ) alternatives, that is, integrated process of order d, where d is a fractional number. We provide the exact order of magnitude of the modified D W test when the data generating process is an I ( d ) process with d E (0. 1.5). Moreover, the consistency of the modified DW statistic as a unit root test against I ( d ) alternatives with d E ( 0 , l ) U ( 1 , 1.5) is proved in this paper. In addition to the theoretical analysis, Monte Carlo experiments show that the performance of the modified D W statistic reveals that it can be used as a unit root test against I ( d ) alternatives.     

The Prospects for Digital Radio

Digital audio broadcasting is a major innovation in radio, one that is at its most advanced in Europe. It has the potential to deliver high-quality audio reception and to increase significantly the capacity of the radio spectrum, with the possibility of an expansion of both the range and diversity of radio programming. Nevertheless, in the UK and elsewhere it remains relatively unknown and under-adopted in comparison with other consumer technologies like digital television. This article examines the origins of digital radio, and considers how this technology is expected to become a mass communications technology, eventually supplanting analogue radio. However, in its present form, there is little that is novel currently being offered on digital radio, and the economic and political contexts in which it is being developed may encourage further concentration of ownership and reduce diversity of choice in listening. Unlike previous innovations then, such as FM broadcasting, there appear to be few compelling advantages of digital radio that will persuade listeners to adopt this new technology. If this new technological system is to succeed, alternative uses must be found for it, and one area for which it might be suited is mobile data communications. The article concludes by suggesting that this might mean that radio becomes of secondary importance to this potentially lucrative application of digital audio broadcasting technology.     

Markov Chain Monte Carlo in small worlds

As the number of applications for Markov Chain Monte Carlo (MCMC) grows, the power of these methods as well as their shortcomings become more apparent. While MCMC yields an almost automatic way to sample a space according to some distribution, its implementations often fall short of this task as they may lead to chains which converge too slowly or get trapped within one mode of a multi-modal space. Moreover, it may be difficult to determine if a chain is only sampling a certain area of the space or if it has indeed reached stationarity. In this paper, we show how a simple modification of the proposal mechanism results in faster convergence of the chain and helps to circumvent the problems described above. This mechanism, which is based on an idea from the field of “small-world” networks, amounts to adding occasional “wild” proposals to any local proposal scheme. We demonstrate through both theory and extensive simulations, that these new proposal distributions can greatly outperform the traditional local proposals when it comes to exploring complex heterogenous spaces and multi-modal distributions. Our method can easily be applied to most, if not all, problems involving MCMC and unlike many other remedies which improve the performance of MCMC it preserves the simplicity of the underlying algorithm.     

Statisticians in stained glass houses

Statistics and stained glass may seem an odd combination, but the windows of Gonville & Caius College, Cambridge, say otherwise. Anthony Edwards explains.     

Local information and the design of sequential hypothesis tests

Various results on sequential hypotheses testing are reviewed. Optimal stopping rules are related to a local measure of statistical information. In some cases, local information can be approximated by L-numbers discovered by Lorden, and simple rules based on these approximations are asymptotically optimal to better order than the cost for a single observation.