Investigating the influence of outcome utility on estimates of probability

This thesis is concerned with the rationality of human probability estimates, specifically the potential influence of outcome utility on estimates of probability. Intuitively, and normatively, the desirability of an outcome should not make that outcome seem more or less likely to occur. Chapter 1 provides a background to the subsequent empirical work by addressing some general issues surrounding a probabilistic approach to human reasoning. The major questions addressed are whether people represent uncertainty quantitatively and their competence at doing so, considered with reference to the status of extant biases in the literature on human probability judgment. Chapter 2 presents seven studies investigating the effect of negative utility on estimates of probability, using a minimal paradigm in which there is a visually defined, objective, probability. When there was an indication that future human action could influence the likelihood of an outcome (the outcome was, in some way, controllable), negative outcomes were rated as more likely to occur than neutral outcomes.. This moderating effect of control can be given a decision-theoretic explanation in terms of loss function asymmetry (e.g., Weber, 1994). Consequently, these effects can be understood as rational reactions to the recognition of the uncertainty of human cognition. Chapter 3 investigates the effects of positive utility using the same visual representation of probability. Across four studies, no effect of positive outcome utility was observed, a result consistent with the asymmetric loss function explanation proposed for the findings in Chapter 2. Chapter 4 presents a statistical-based critique of the 'unrealistic optimism' phenomenon (e.g., Weinstein, 1980). Additionally, two empirical studies failed to find any evidence that the 'unrealistic optimism' phenomenon is more than just a statistical artifact. The results from all three experimental chapters provide support for the contention that people's probability estimates are not systematically biased by utility considerations.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Investigating the influence of outcome utility on estimates of probability

This thesis is concerned with the rationality of human probability estimates, specifically the potential influence of outcome utility on estimates of probability. Intuitively, and normatively, the desirability of an outcome should not make that outcome seem more or less likely to occur. Chapter 1 provides a background to the subsequent empirical work by addressing some general issues surrounding a probabilistic approach to human reasoning. The major questions addressed are whether people represent uncertainty quantitatively and their competence at doing so, considered with reference to the status of extant biases in the literature on human probability judgment. Chapter 2 presents seven studies investigating the effect of negative utility on estimates of probability, using a minimal paradigm in which there is a visually defined, objective, probability. When there was an indication that future human action could influence the likelihood of an outcome (the outcome was, in some way, controllable), negative outcomes were rated as more likely to occur than neutral outcomes.. This moderating effect of control can be given a decision-theoretic explanation in terms of loss function asymmetry (e.g., Weber, 1994). Consequently, these effects can be understood as rational reactions to the recognition of the uncertainty of human cognition. Chapter 3 investigates the effects of positive utility using the same visual representation of probability. Across four studies, no effect of positive outcome utility was observed, a result consistent with the asymmetric loss function explanation proposed for the findings in Chapter 2. Chapter 4 presents a statistical-based critique of the 'unrealistic optimism' phenomenon (e.g., Weinstein, 1980). Additionally, two empirical studies failed to find any evidence that the 'unrealistic optimism' phenomenon is more than just a statistical artifact. The results from all three experimental chapters provide support for the contention that people's probability estimates are not systematically biased by utility considerations

Lost in translation? Interpretations of the probability phrases used by the Intergovernmental Panel on Climate Change in China and the UK

Tackling climate change is a global challenge and the Intergovernmental Panel on Climate Change (IPCC) is the organisation charged with communicating the risks, dangers and mechanisms underlying climate change to both policy makers and the general public. The IPCC has traditionally used words (e.g., ‘likely’) in place of numbers (‘70 % chance’) to communicate risk and uncertainty information. The IPCC assessment reports have been published in six languages, but the consistency of the interpretation of these words cross-culturally has yet to be investigated. In two studies, we find considerable variation in the interpretation of the IPCC’s probability expressions between the Chinese and British public. Whilst British interpretations differ somewhat from the IPCC’s prescriptions, Chinese interpretations differ to a much greater degree and show more variation. These results add weight to continuing calls for the IPCC to make greater use of numbers in its forecasts

The average laboratory samples a population of 7,300 Amazon Mechanical Turk workers

Using capture-recapture analysis we estimate the effective size of the active Amazon Mechanical Turk (MTurk) population that a typical laboratory can access to be about 7,300 workers. We also estimate that the time taken for half of the workers to leave the MTurk pool and be replaced is about 7 months. Each laboratory has its own population pool which overlaps, often extensively, with the hundreds of other laboratories using MTurk. Our estimate is based on a sample of 114,460 completed sessions from 33,408 unique participants and 689 sessions across seven laboratories in the US, Europe, and Australia from January 2012 to March 2015

Chandra Discovery of a 300 kpc X-ray Jet in the GPS Quasar PKS1127-145

We have discovered an X-ray jet with Chandra imaging of the z=1.187 radio-loud quasar PKS1127-145. In this paper we present the Chandra X-ray data, follow-up VLA observations, and optical imaging using the HST WFPC2. The X-ray jet contains 273+/-5 net counts in 27ksec and extends ~30 arcsec, from the quasar core, corresponding to a minimum projected linear size of ~330/h_50 kpc. The evaluation of the X-ray emission processes is complicated by the observed offsets between X-ray and radio brightness peaks. We discuss the problems posed by these observations to jet models. In addition, PKS1127-145 is a Giga-Hertz Peaked Spectrum radio source, a member of the class of radio sources suspected to be young or ``frustrated'' versions of FRI radio galaxies. However the discovery of an X-ray and radio jet extending well outside the host galaxy of PKS1127-145 suggests that activity in this and other GPS sources may be long-lived and complex.Comment: 22 pages, 11 ps figures, 1 figure in a JPG file, 3 tables. AASTEX. Accepted by The Astrophysical Journa

Rotational Variation of Daughter Species Production Rates in Comet 103P/Hartley: Implications for the Progeny of Daughter Species and the Degree of Chemical Heterogeneity

We present analysis of high spectral resolution optical spectra of Comet 103P/Hartley taken during its Fall 2010 apparition. These spectra include transitions belonging to CN, C2, CH, NH2, and OI. We measure production rates and mixing ratios from these spectra. We find evidence for large changes in production rates (factors of a few) over the course of a nucleus rotation, in agreement with other measurements. We also measure variability with rotational phase in the CN/H2O and C2/CN ratios, which has not been previously reported for any comet. There may also be variability in the NH2/H2O ratio with rotational phase, but this trend is not as clear as for CN/H2O. We interpret the changing mixing ratios as due to H2O and C2 being released primarily from the icy grain halo, while the CN parent molecule comes directly from the nucleus. There is evidence that the CH/CN ratio is higher pre-perihelion than post-perihelion. We conclude that the observed CN and NH2 abundances are consistent with HCN and NH3 being the dominant parent molecules for these species. The C2 and CH abundances are higher than those of candidate parent molecules (C2H2 and CH4 respectively), so there must be another source for these molecules in 103P's coma. Carbonaceous dust grains could serve as this source

Optimal technical management of stump closure following distal pancreatectomy: a retrospective review of 215 cases.

BACKGROUND: Pancreatic fistula (PF) is a major source of morbidity following distal pancreatectomy (DP). Our aim was to identify risk factors related to PF following DP and to determine the impact of technique of transection and stump closure. METHODS: We performed a retrospective review of 215 consecutive patients who underwent DP. Perioperative and postoperative data were collected and analyzed with attention to PF as defined by the International Study Group of Pancreatic Fistula. RESULTS: PF developed in 36 patients (16.7%); fistulas were classified as Grade A (44.4%), B (44.4%), or C (11.1%). The pancreas was transected with stapler (n = 139), cautery (n = 70), and scalpel (n = 3). PF developed in 19.8% of remnants which were stapled/oversewn and 27.7% that were stapled alone (p = 0.4). Of the 69 pancreatic remnants transected with cautery and oversewn, a fistula developed in 4.3% (p = 0.004 compared to stapled/oversewn; p = 0.006 compared to stapled/not sewn). The median length of postoperative hospital stay was significantly increased in patients who developed PF (10 vs. 6 days, p = 0.002) CONCLUSION: The method of transection and management of the pancreatic remnant plays a critical role in the formation of PF following DP. This series suggests that transection using electrocautery followed by oversewing of the pancreatic remnant has the lowest risk of PF

CD70 (TNFSF7) is expressed at high prevalence in renal cell carcinomas and is rapidly internalised on antibody binding

In order to identify potential markers of renal cancer, the plasma membrane protein content of renal cell carcinoma (RCC)-derived cell lines was annotated using a proteomics process. One unusual protein identified at high levels in A498 and 786-O cells was CD70 (TNFSF7), a type II transmembrane receptor normally expressed on a subset of B, T and NK cells, where it plays a costimulatory role in immune cell activation. Immunohistochemical analysis of CD70 expression in multiple carcinoma types demonstrated strong CD70 staining in RCC tissues. Metastatic tissues from eight of 11 patients with clear cell RCC were positive for CD70 expression. Immunocytochemical analysis demonstrated that binding of an anti-CD70 antibody to CD70 endogenously expressed on the surface of A498 and 786-O cell lines resulted in the rapid internalisation of the antibody–receptor complex. Coincubation of the internalising anti-CD70 antibody with a saporin-conjugated secondary antibody before addition to A498 cells resulted in 50% cell killing. These data indicate that CD70 represents a potential target antigen for toxin-conjugated therapeutic antibody treatment of RCC