Controlling Restricted Random Testing: An Examination of the Exclusion Ratio Parameter

In Restricted Random Testing (RRT), the main control parameter is the Target Exclusion Ratio (R), the proportion of the input domain to be excluded from test case generation at each iteration. Empirical investigations have consistently indicated that best failure-finding performance is achieved when the value for the Target Exclusion Ratio is maximised, i.e. close to 100%. This paper explains an algorithm to calculate the Actual Exclusion Ratio for RRT, and applies the algorithm to several simulations, confirming that previous empirically determined values for the Maximum Target Exclusion Ratio do give Actual Exclusion Ratios close to 100%. Previously observed trends of improvement in failure-finding efficiency of RRT corresponding to increases in Target Exclusion Ratios are also identified for Actual Exclusion Ratios.published_or_final_versio

Insider trading and family firms

We find that CEOs of S&P 1500 family firms, founding CEOs in particular, are more active stock traders than are the CEOs of non-family firms. Importantly, the stock trades made by founding CEOs (and, to a lesser extent, those made by founders’ descendants) are more profitable than those made by the CEOs of non-family firms. This finding is more pronounced for family firms that are difficult to value or that have poor corporate governance. Founding CEOs’ excess stock trading returns arise both from trades made before earnings surprises and those made outside earnings announcement periods. Finally, founding CEOs’ trades forecast their company’s future stock returns better than those made by the CEOs of non-family firms.postprintThe 37th Annual Meeting of the European Finance Association (EFA), Frankfurt, Germany, 25-28 August 2010

Hidden Markov model analysis reveals better eye movement strategies in face recognition

Conference Theme: Mind, Technology, and SocietyHere we explored eye movement strategies that lead to better performance in face recognition with hidden Markov models (HMMs). Participants performed a standard face recognition memory task with eye movements recorded. The durations and locations of the fixations were analyzed using HMMs for both the study and the test phases. Results showed that in the study phase, the participants who looked more often at the eyes and shifted between different regions on the face with long fixation durations had better performances. The test phase analyses revealed that an efficient, short first orienting fixation followed by a more analytic pattern focusing mainly on the eyes led to better performances. These strategies could not be revealed by analysis methods that do not take individual differences in both temporal and spatial dimensions of eye movements into account, demonstrating the power of the HMM approach.postprin

Software testing education and training in Hong Kong

While the use of computer applications is widely spread in every business and, hence, the reliability of software is critical, it is believed that many organizations involved in software development do not take software testing sufficiently seriously as an important task. It is worthwhile to find out how far organizations are carrying out software testing in a systematic and structured manner or still taking on an ad-hoc approach. A survey was conducted to understand the software testing practices and the level of related education and training in Hong Kong. It was found that most testing team members did not have formal training in software testing. University curricula generally did not prepare graduates with enough coverage in software testing. It is proposed that a review of the current software engineering curricula in the universities to examine the coverage of software testing will be useful to the development of quality software. © 2005 IEEE.published_or_final_versio

Radiologist variability in assessing the position of the cavoatrial junction on chest radiographs

Objectives: To assess the variability in identifying the cavo-atrial junction (CAJ) on chest x-rays amongst radiologists. Methods: Twenty-three radiologists (13 consultants and 10 trainees) assessed 25 postero-anterior erect chest x-rays (including eight duplicates) and marked the positions of the CAJ. Differences in the CAJ position both within and between observers were evaluated and reported as limits of agreement, repeatability coefficients, intra-class correlation coefficients and displayed graphically with Bland- Altman plots. Results: The mean difference for within observer assessments was -0.2 cm (95% limits of agreement, -1.5 to +1.1 cm) and between observers was -0.3 cm (95% limits of agreement, -2.5 to +1.8 cm). Intra-observer repeatability coefficients (RC) were marginally lower for consultants when compared to trainees (1.1 versus 1.5). RCs between observers were comparable (2.1 versus 2.2) for for consultants and trainees, respectively. Conclusions: This study detected a large inter-observer variability of the CAJ position (up to 4.3 cm). This is a significant finding considering that the length of the SVC is reported to be approximately 7cm. We conclude that there is poor consensus regarding the CAJ position amongst radiologists. Advances in knowledge: No comparisons exist between radiologists in determining CAJ position from chest X-rays. This report provides evidence of the large observer variability amongst radiologists and adds to the discussion regarding the use of chest X-rays in validating catheter tip location systems

Piezoelectric micromachined ultrasonic transducers based on P(VDF-TrFE) copolymer thin films

2006-2007 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Test case selection with and without replacement

Previous theoretical studies on the effectiveness of partition testing and random testing have assumed that test cases are selected with replacement. Although this assumption has been well known to be less realistic, it has still been used in previous theoretical work because it renders the analyses more tractable. This paper presents a theoretical investigation aimed at comparing the effectiveness when test cases are selected with and without replacement, and exploring the relationships between these two scenarios. We propose a new effectiveness metric for software testing, namely the expected number of distinct failures detected, to re-examine existing partition testing strategies.postprin

Mind reading: discovering individual preferences from eye movements using switching hidden Markov models

Conference Theme: Integrating Psychological, Philosophical, Linguistic, Computational and Neural PerspectivesPoster Session 3: no. 33Here we used a hidden Markov model (HMM) based approach to infer individual choices from eye movements in preference decision-making. We assumed that during a decision making process, participants may switch between exploration and decision-making periods, and this behavior can be better captured with a Switching HMM (SHMM). Through clustering individual eye movement patterns described in SHMMs, we automatically discovered two groups of participants with different decision making behavior. One group showed a strong and early bias to look more often at the to-be chosen stimulus (i.e., the gaze cascade effect; Shimojo et al., 2003) with a short final decision-making period. The other group showed a weaker cascade effect with a longer final decision- making period. The SHMMs also showed capable of inferring participants’ preference choice on each trial with high accuracy. Thus, our SHMM approach made it possible to reveal individual differences in decision making and discover individual preferences from eye movement data.postprin

Cancer pain managment: experience of 702 consecutive cases in a teaching hospital in Hong Kong

Effective pain control is essential in the management of patients with cancer. We present here our experience in the management of 702 patients with cancer pain by the Pain Management Team, Department of Anaesthesiology, Queen Mary Hospital. Patients were discharged from the Pain Management Team with a visual analogue scale of pain (VAS) less than 3 in 87.7% of cases, and more than 90% of patients had improved appetite and sleep on discharge. These promising results were achieved through an emphasis on comfort and function, close liaison among clinicians from different specialties, and a variety of analgesic modalities. Oral drugs remained the mainstay of treatment, supplemented by alternative routes of drug administration such as subcutaneous, intravenous and transdermal delivery. Main side effects observed included nausea (16%) and constipation (8%). Neural blockade, including coeliac plexus blockade, and intercostal nerve blockade, and administration of opioids via subarachnoid or epidural routes were also employed in selected patients.published_or_final_versio

12-Month naturalistic outcomes of depressive disorders in Hong Kong's primary care

Open Access Journalpublished_or_final_versio