Sequential decision making with adaptive utility

Decision making with adaptive utility provides a generalisation to classical Bayesian decision theory, allowing the creation of a normative theory for decision selection when preferences are initially uncertain. The theory of adaptive utility was introduced by Cyert & DeGroot [27], but had since received little attention or development. In particular, foundational issues had not been explored and no consideration had been given to the generalisation of traditional utility concepts such as value of information or risk aversion. This thesis addresses such issues. An in-depth review of the decision theory literature is given, detailing differences in assumptions between various proposed normative theories and their possible generalisations. Motivation is provided for generalising expected utility theory to permit uncertain preferences, and it is argued that in such a situation, under the acceptance of traditional utility axioms, the decision maker should seek to select decisions so asto maximise expected adaptive utility . The possible applications of the theory forsequential decision making are illustrated by some small-scale examples, including examples of relevance within reliability theory

Nonparametric Predictive Utility Inference

We consider the natural combination of two strands of recent statistical research, i.e., that of decision making with uncertain utility and that of Nonparametric Predictive Inference (NPI). In doing so we present the idea of Nonparametric Predictive Utility Inference (NPUI), which is suggested as a possible strategy for the problem of utility induction in cases of extremely vague prior information. An example of the use of NPUI within a motivating sequential decision problem is also considered for two extreme selection criteria, i.e., a rule that is based on an attitude of extreme pessimism and a rule that is based on an attitude of extreme optimism

Adaptive utility and trial aversion

Decision making with adaptive utility provides a generalisation to classical Bayesian decision theory, allowing the creation of a normative theory for decision selection when preferences are initially uncertain. In this paper we address some of the foundational issues of adaptive utility as seen from the perspective of a Bayesian statistician. The implications that such a generalisation has upon the traditional utility concepts of value of information and risk aversion are also explored, with a new concept of trial aversion introduced that is similar to risk aversion, but which concerns a decision maker\u27s aversion to selecting decisions with high uncertainty over resulting utility

Predicting total global species richness using rates of species description and estimates of taxonomic effort

We found that trends in the rate of description of 580,000 marine and terrestrial species, in the taxonomically authoritative World Register of Marine Species and Catalogue of Life databases, were similar until the 1950s. Since then, the relative number of marine to terrestrial species described per year has increased, reflecting the less explored nature of the oceans. From the mid-19th century, the cumulative number of species described has been linear, with the highest number of species described in the decade of 1900, and fewer species described and fewer authors active during the World Wars. There were more authors describing species since the 1960s, indicating greater taxonomic effort. There were fewer species described per author since the 1920s, suggesting it has become more difficult to discover new species. There was no evidence of any change in individual effort by taxonomists. Using a nonhomogeneous renewal process model we predicted that 24?31% to 21?29% more marine and terrestrial species remain to be discovered, respectively. We discuss why we consider that marine species comprise only 16% of all species on Earth although the oceans contain a greater phylogenetic diversity than occurs on land. We predict that there may be 1.8?2.0 million species on Earth, of which about 0.3 million are marine, significantly less than some previous estimates

58th Congress of the International Statistical Institute

The offence risk posed by individuals who are arrested, but where subsequently no charge or caution is administered, has been used as an argument for justifying the retention of such individuals? DNA and identification profiles. Here we consider the UK Home Office arrest-to-arrest data analysis, and find it to have limited use in indicating risk of future offence. In doing so, we consider the appropriateness of the statistical methodology employed and the implicit assumptions necessary for making such inference concerning the re-arrest risk of a further individual. Additionally, we offer an alternative model that would provide an equally accurate fit to the data, but which would appear to have sounder theoretical justification. Finally, we consider the implications of using such statistical inference in formulating national policy, and highlight a number of sociological factors that could be taken into account so as to enhance the validity of any future analysis

Considerations on the UK re-arrest hazard data analysis: how model selection can alter conclusions for policy development

At time of writing, the policy of DNA profile retention for Constabularies within England and Wales is determined by the Association of Chief Police Officer’s (ACPO) 2006 Retention Guidelines for Nominal Records on the Police National Computer (PNC), which was developed following the passing of the Criminal and Police Act 2001 and the Criminal Justice Act 2003. The former of these legislations ended the requirement for Constabularies to destroy DNA records relating to persons acquitted or who had their case discontinued, whilst the latter extended powers so as to permit the taking of DNA records without consent from any individual arrested for a recordable offence. These Retention Guidelines detail a governing principle that all records held on the PNC should be maintained until the person in question reaches 100 years of age, regardless of status of conviction, caution, acquittal, or No Further Action (NFA). As such, by 2010 there were over 5 million persons with profiles on the UK National DNA database, with approximately 1 million of these having no record of conviction or caution

Data from: More taxonomists describing significantly fewer species per unit effort may indicate that most species have been discovered

Recent studies show that there are more taxonomists describing species in recent decades than before. However, whether the rate of increase in number of taxonomists is greater than the rate of new species description has been questioned. We found a statistically significant decline in the proportion of species being described per number of taxonomists (i.e. authors of recent species descriptions) during the past century for (a) families of insects that had been stated not to show this trend, and (b) a sample of over 0.5 million marine, terrestrial and freshwater species. We suggest that this decreased ‘catch’ of species per taxonomic effort, despite scientists’ greater ability to explore and sample habitats, means it is getting harder to discover new species, and supports recent studies suggesting that two-thirds of all species have been named

Workshop on Stochastic Processes for Wireless Networks

Abstract?This paper considers the use of a recently developed Bayesian statistical approximation technique that leads to very fast determination of highly accurate estimates for latent radio signal power. Following suitable data analysis, a first order non-stationary auto-regressive process is considered for latent radio signal and the fast approximation technique is then used to provide accurate estimates of the hidden model parameters. These estimates are based on having received several noisy, but spatially correlated, observations of the true latent signal. The implication of this technique for real time decision analysis and the problem of finding, and making use of, so-called radio spectrum holes is also discussed

Factors influencing when species are first named and estimating global species richness

Estimates of global species richness should consider what factors influence the rate of species discovery at global scales. However, past studies only considered regional scales and/or samples representing <0.4% of all named species. Here, we analysed trends in the rate of description for all fish species (2% of all named species). We found that the number of species described has slowed for (a) brackish compared to marine and freshwater species, (b) large compared to small sized fish, (c) geographically widespread compared to localised, (d) species occurring in the tropics and northern hemisphere compared to southern hemisphere, and (e) neritic (coastal) species compared to pelagic (offshore) species. Most (68%) of the variation in year of description was related to geographic location and depth, and contrary to expectations, body size was a minor factor at just 6% (on a standardised scale). Thus most undiscovered species will have small geographic ranges, but will not necessarily be of smaller body size than currently known species. Accordingly, global assessments of how many species may exist on Earth need to account for geographic variation