The Effects of Rounding on the Consumer Price Index

The Bureau of Labor Statistics rounds the Consumer Price Index (CPI) to a single decimal place before releasing it, and the published CPI inflation series is calculated from those rounded index values. While rounding has only a relatively small effect on the level of the CPI series at present, it can have a significant effct on CPI inflation, the monthly percent changes in the CPI. This paper estimates the impact of rounding error on the published CPI inflation for both contemporaneous and historical data. Using an unrounded CPI series from January 1986 to July 2005 as a benchmark, I find that published CPI inflation differs from its full-precision counterpart approximately 25% of the time, and that reporting the CPI levels to three decimal places would reduce these discrepancies to under 0.5%. Further, the variance introduced by rounding error is large when compared to the sampling variation in CPI inflation. I find that the BLS could reduce total CPI inflation error variance by 42% by simply reporting more digits in the CPI index, resulting in a significantly more accurate reflection of monthly inflation. In order to extend these results to the CPI historical series, I derive the distribution of the rounding error component of inflation. From this analysis, it is possible to estimate the probability of large rounding errors for a given CPI level and rounding precision. Three regimes emerge. Before the 1970’s inflation, discrepancies due to rounding were both frequent and frequently large relative to the underlying inflation rate. During the inflationary period of the mid-1970’s to mid-1980’s, both the probability and relative magnitude of discrepancies decrease dramatically. Finally, the last twenty years are characterized by a slowly falling probability of any rounding-induced error, but a roughly constant probability of an error of a given size.Consumer Price Index, Variance, Rounding, Inflation

The importance of collegiality and reciprocal learning in the professional development of beginning teachers

This paper discusses factors which enhance induction experiences for beginning teachers. It reports the findings from case studies which explore the impact of new entrants to the teaching profession in Scotland. The data suggest that the most supportive induction processes mix both formal and informal elements, but that the informal elements such as collegiality, good communication and a welcoming workplace environment should not be underestimated. The study also highlights the potential benefits of a more collegiate environment for teachers across the career phases. Experienced teachers and new entrants had a range of experience to offer each other, thus creating more cohesive professional working which was supportive of early career teachers while encouraging reflection on practice among the more experienced professionals

Gastrointestinal parasites of feral cats from Christmas Island

Objective To investigate the gastrointestinal parasites present in feral cats on Christmas Island, with particular interest in the protozoan parasite Toxoplasma gondii. Procedure Faecal and serum samples were collected from 28 and 25 cats respectively that were trapped as part of an ongoing eradication program being run on Christmas Island by the Department of Environment and Conservation. Faecal samples were screened microscopically for helminth and protozoan parasites. Serum samples were screened for antibodies to T gondii using a commercial indirect immunofluorescence assay (IFA) and a latex agglutination test (LAT). Results The most common helminth parasites detected were Toxocara cati (present in 15 of 28 faecal samples), Strongyloides sp (13/28), Aelurostrongylus abstrusus, (7/28), an unidentified capillarid (6/28) and Ancylostoma sp (4/28). Based on serology, T gondii was the most common parasite detected (protozoan or otherwise) with antibodies detected in 24 serum samples by IFA and 23 serum samples by LAT. Conclusion Cats on Christmas Island harbour many of the helminth and protozoan parasites reported from feral cats elsewhere in Australia. The high seroprevalence of T gondii in these cats indicates a high level of exposure to the parasite in this environment

Temperature Effects on Development of Three Cereal Aphid Parasitoids (Hymenoptera: Aphidiidae)

Temperature is an important climatological variable that influences the biology and ecology of insects. Poor climatic adaptation can limit the effectiveness of parasitic insects in biological control. Two exotic parasites (Syrian Diaeretiella rapae (M\u27Intosh) and Argentinean Aphidius colemani Viereck) imported for biological control of the Russian wheat aphid, Diuraphis noxia (Mordvilko), and one native parasite (Diaeretiella rapae) were reared in growth chambers in three fluctuating temperature regimes with average daily temperatures of 12, 18, and 24°C. Estimates of temperature thresholds for immature development were 3.3, 3.5, and 2.8°C, for Oklahoman D. rapae, Syrian D. rapae, and A. colemani, respectively. Estimates of thermal require- ments for development from egg to adult were 297, 278, and 301 degree-days for the three parasitoids. Dry weights of adults reared in different fluctuating temperature regimes did not differ significantly among sexes, but adults from regimes with low average temperatures of 12 and 18°C had significantly greater weights than those reared in a regime with an average temperature of 24°C. Results suggest that developmental response to temperature will not limit the effectiveness of the exotic parasites in biological control

DScent Final Report

DScent was a joint project between five UK universities combining research theories in the disciplines of computational inference, forensic psychology and expert decision-making in the area of counter-terrorism. This document discusses the work carried out by Leeds Metropolitan University which covers the research, design and development work of an investigator support system in the area of deception using artificial intelligence. For the purposes of data generation along with system and hypothesis testing the project team devised two closed world games, the Cutting Corners Board Game and the Location Based Game. DScentTrail presents the investigator with a ‘scent trail’ of a suspect’s behaviour over time, allowing the investigator to present multiple challenges to a suspect from which they may prove the suspect guilty outright or receive cognitive or emotional clues of deception (Ekman 2002; Ekman & Frank 1993; Ekman & Yuille 1989; Hocking & Leathers 1980; Knapp & Comadena 1979). A scent trail is a collection of ordered, relevant behavioural information over time for a suspect. There are links into a neural network, which attempts to identify deceptive behavioural patterns of individuals. Preliminary work was carried out on a behavioural based AI module which would work separately alongside the neural network, with both identifying deception before integrating their results to update DScentTrail. Unfortunately the data that was necessary to design such a system was not provided and therefore, this section of research only reached its preliminary stages. To date research has shown that there are no specific patterns of deceptive behaviour that are consistent in all people, across all situations (Zuckerman 1981). DScentTrail is a decision support system, incorporating artificial intelligence (AI), which is intended to be used by investigators and attempts to find ways around the problem stated by Zuckerman above

A generalized vortex lattice method for subsonic and supersonic flow applications

If the discrete vortex lattice is considered as an approximation to the surface-distributed vorticity, then the concept of the generalized principal part of an integral yields a residual term to the vorticity-induced velocity field. The proper incorporation of this term to the velocity field generated by the discrete vortex lines renders the present vortex lattice method valid for supersonic flow. Special techniques for simulating nonzero thickness lifting surfaces and fusiform bodies with vortex lattice elements are included. Thickness effects of wing-like components are simulated by a double (biplanar) vortex lattice layer, and fusiform bodies are represented by a vortex grid arranged on a series of concentrical cylindrical surfaces. The analysis of sideslip effects by the subject method is described. Numerical considerations peculiar to the application of these techniques are also discussed. The method has been implemented in a digital computer code. A users manual is included along with a complete FORTRAN compilation, an executed case, and conversion programs for transforming input for the NASA wave drag program

Genetic Diversity in an Invasive Clonal Plant? A Historical and Contemporary Perspective

Introduced populations of Eichhornia crassipes (Pontederiaceae) possess extremely low levels of genetic diversity due to severe bottleneck events and clonal reproduction. While populations elsewhere have been well studied, North American populations of E. crassipes remain understudied. We used Amplified Fragment Length Polymorphism markers to assess genetic diversity and population structure in North American E. crassipes populations. Patterns of diversity over the past fifty years were analyzed using herbarium specimens. Furthermore, we sampled populations across the Gulf Coast of the United States throughout a year to determine contemporary genetic diversity and assess potential seasonal effects. Genetic diversity was found to be scant in the United States without population structure, agreeing with previous studies from other regions. Genetic diversity has remained consistently low over the past fifty years despite significant changes in selection pressure. However, evidence for and against population structure between seasons was found and the consequences of this are discussed