published_or_final_version / Public Health / Master / Master of Public Health

This thesis includes two essays on equity analysts’ agent role and one essay on investors’ inattention to good news. From a broader economic perspective, equity analysts are essentially agents acting on behalf of multiple principals including their employers, investors and issuers (Fisch & Sale, 2003). Classic agency theory predicts that analysts selectively provide coverage and report their expectations. In the first essay, I examine empirically if incremental investment value can be uncovered from analysts’ choices between silence and speech, measured as the level of analyst reporting not explained by size or turnover. I find that “silence” negatively, and “speech” positively predicts future stock returns. More importantly, as “speech is silver, silence is golden”, the observed price shift is mainly driven by silence, providing evidence that analysts’ inaction can impede price discovery process. This is consistent with the claims that analysts’ expectations are based on valid information, that analyst self-selection is pervasive due to the principal-agent conflicts, and that the loss of information with analyst silence has resulted in some mis-valuation which can be viewed as a form of classic agency cost. The second essay tests if analysts are systematically less forthcoming in reporting bad earnings news when the principal-agent conflicts are exacerbated. I find that analysts’ downward consensus earnings forecast revisions are less informative than their upward revisions; that less is more when analysts report bad news - extreme downward revisions contain little incremental information beyond momentum compared with moderate downward revisions; and that the differential richness of information in good and bad news revisions is more pronounced among bigger, more heavily covered stocks and stocks with higher institutional holdings, namely, stocks that are typically more prone to the analyst agency problem. Thus the loss of information in bad news revisions and extreme bad news revisions’ lagging behind price action can be viewed as another form of agency cost. In the third essay, I investigate how negativity bias in information processing affects the positive-negative-asymmetry in the stock price continuation phenomenon. Psychology literature document that negative stimuli elicit more attention and negative information is generally processed more thoroughly and is weighed more heavily in impression formation, memory, learning and decision making than positive information (Baumeister, Bratslavsky, Finkenauer, & Vohs, 2001; Rozin & Royzman, 2001). Insofar as people are cognitive misers, all else being equal, investors tend to pay less attention to good news than to bad news. Using earnings announcement as the information shock, I document evidences that investors incorporate bad earnings news to fuller extent than they do with good earnings news. Furthermore, given that psychological biases are typically increased when there is more uncertainty (Hirshleifer, 2001) and ambiguity or uncertainty is often associated with higher risk and the possibility of hostile manipulation, I also find more pronounced asymmetry in post announcement drift when information uncertainty is greater. / published_or_final_version / Business / Doctoral / Doctor of Philosophy

Background: Jaw corrective surgery can cause significant psychosocial impacts on patients. This prospective study aimed to investigate the longitudinal changes of psychosocial characteristics of patients with dentofacial deformities after corrective surgery and the factors that predict the psychological resilience of Hong Kong Chinese undergoing this type of surgery. Materials and Methods: A prospective cohort study was carried out from 1st June 2011 to 31st December 2012 on Hong Kong Chinese patients, who had corrective surgery as treatment for their dentofacial deformities. Self-completed questionnaires, including Brief Symptom Inventory (BSI), Adult Trait Hope Scale (AHS), Hospital Anxiety and Depression Scale (HADS), Life Orientation Test (LOT), Social Avoidance and Distress Scale (SADS) and Satisfaction with Life Scale (SWLS), were administered to each patient at the surgical consent signing date (T1), one pre-operative day (T2), 1-2 post-operative week (T3) and 3rd post-operative month (T4). Psychological outcome trajectories were established using the BSI General Severity index (GSI) at T1, T3 and T4. Five patterns of outcome trajectories were created using specified outcome measures of psychological distress level, including chronic dysfunction, recovery, delayed dysfunction, resilience and others. They were then categorized into two patterns of outcome trajectories (resilience and non-resilience groups) for analysis. Independence sample t-test and logistic regression analyses were conducted to investigate the significance of life orientation level at baseline to predict resilience. Results: 67 participants (23 males, 44 females; mean age 25.6) were recruited in the study. Highest hope level and psychological distress level was noted pre-operatively at the surgical consent signing date. The levels then dropped post-operatively in the first 3 months. No statistically significant difference was noted on the depression and anxiety level, social avoidance and distress level, optimism level and life satisfaction level from pre-operative to post-operative stages. The proportion of the five patterns of outcome trajectories was chronic dysfunction (22.4%), recovery (7.5%), delayed dysfunction (3%), resilience (43.3%) and others (23.8%). The logistic regression analyses showed that the pre-operative baseline optimism level of LOT was a significant predictor on the resilience characteristic of a patient after orthognathic corrective surgery. Conclusion: Patients with dentofacial deformities have high level of hope and equally high level of psychological distress at the surgical consent stage of orthognathic surgery. Their psychological distress and hope levels tend to drop during the first three post-operative months. There is no expected peri-operative change on the depression and anxiety symptoms, social avoidance and distress, optimism level as well as life satisfaction level in these patients. Optimism level can predict the psychological resilience of a Hong Kong Chinese in going through orthognathic surgery. Brief Symptom Inventory (BSI) and Life Orientation Test (LOT) are recommended as preoperative psychological screening tools. / published_or_final_version / Dental Surgery / Master / Master of Dental Surgery

Much research has looked into how aerobic exericse is important to physical and psychological well-being. However, research is less sure of the how exercise produces psychological benefits. To explore this, running is a form of exercise that deserves particular attention given its possible usefulness to public policy discussions. Running is one of the most accessible and inexpensive forms of exercise, and its popularity is demonstrated by the trend of more and more people participating in local annual marathons. This study performed a longitudinal test to better define the conditions under which average people might enjoy psychological benefits from exercise like running. From self-determination theory (Deci & Ryan, 1985), motivation is fueled by three basic psychological needs: perceived competence, perceived relatedness and perceived autonomy. In this study, key factors influencing psychological outcomes included runners’ degree of motivation, perceived relatedness and the intensity of their training program. The present study had 59 average runners fill in questionnaires before and after a 12 week marathon training program. The results showed that stress and depression levels were significantly reduced, and perceived relatedness among runners increased. Runners’ degree of motivation, which refers to the degree to which runners felt intrinsically motivated, predicts depression and stress levels after training. It suggested that a higher degree of motivation maximizing stress and depression reduction. In addition, higher levels of perceived relatedness among runners also positively predicts stress reduction. The depression reduction of runners who joined only training was significantly higher than those who joined marathon competition after finishing training. The present study found that this competition effect was fully mediated by the number of long runs runners attended during their training. This finding is tied to the question of how much exercise people need in order to optimally reduce depression. Overall, the present study highlights that a threshold of exercise intensity exists beyond which depression reduction becomes insignificant. In the context of the marathon training under study, four or fewer long runs were the recommended threshold. The present study provided a good overview of the psychological benefits of running for a non-clinical population, and also identified how people might maximize such gains. Application of the findings to the promotion of marathon culture for the betterment of public mental health is discussed. / published_or_final_version / Clinical Psychology / Master / Master of Social Sciences

 Rumination is generally defined as a repetition of a theme in thoughts. Rumination has been consistently associated with psychopathologies. Among these psychopathologies, the relationship between depression and rumination is likely the most widely researched. Rumination was found able to predict onset of depression and duration of depressive symptoms. Rumination was also suggested to be a maladaptive coping to stress and distress, which enhance avoidant coping strategies and then further increase depression. Hence, understanding the neural basis of rumination would shed important insight into the mechanisms underpinning the regulation and dysregulation of emotion that would guide the development of cost-effective interventions. Study One was conducted to understand the sex-related differences in the rumination subtypes’ relationships with negative affect and avoidance. Thirty-six healthy participants (23 females, 13 males) were recruited in the community. We found a positive association between brooding and negative affect in both males and females. We also found, as hypothesized, a positive association between brooding and avoidance, and a negative association between reflective pondering and depression in females. A negative association between reflective pondering and avoidance was also found in males. However, reflective pondering was found to be positively associated with depression in males in this study. The findings suggest a gender difference in their emotional regulation. The brain structural correlation with this sex-related behavioral data was investigated through a voxel-based morphometry study. The sex-related difference of rumination subtypes and their relationship with negative affect, avoidance and brain volumes were explored. We found males having a larger gray matter volume over left anterior cingulate than females, and gray matter volume of this region was found to be associated with brooding in the literature. A significant interaction effect of gender and brooding was found over gray matter volume of left lateral parietal, while a significant interaction effect of gender and reflective pondering was found over gray matter volume of the several frontal regions. Consistent with the behavioral study findings, the left inferior temporal, left postcentral and right anterior cingulate were found to be associated with the significant associations between rumination and negative affect found in Study One. We also found the left inferior temporal and right precentral positively associated with brooding and behavioral-nonsocial avoidance in females. This was also found to be consistent with results from Study One. In this study, the sex-related differences among rumination, negative affect and avoidant coping strategies were found to be correlated to the regional gray matter volumes. These findings do not only help us better understand the neural associates behind the sex-related behavioral differences often discussed and found in previous studies, they also give us further information and direction on the management plans of the emotional and avoidance problems associated with rumination. / published_or_final_version / Psychology / Doctoral / Doctor of Philosophy

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