Comparing one-step M-estimators of location when there are more than two groups

Methods for comparing means are known to be highly nonrobust in terms of Type II errors. The problem is that slight shifts from normal distributions toward heavy-tailed distributions inflate the standard error of the sample mean. In contrast, the standard error of various robust measures of location, such as the one-step M-estimator, are relatively unaffected by heavy tails. Wilcox recently examined a method of comparing the one-step M-estimators of location corresponding to two independent groups which provided good control over the probability of a Type I error even for unequal sample sizes, unequal variances, and different shaped distributions. There is a fairly obvious extension of this procedure to pairwise comparisons of more than two independent groups, but simulations reported here indicate that it is unsatisfactory. A slight modification of the procedure is found to give much better results, although some caution must be taken when there are unequal sample sizes and light-tailed distributions. An omnibus test is examined as well.     

Assessment of In-Basket Performance by Quickly-Scored Methods: Development and Psychometric Evaluation

The present research was aimed primarily at establishing and evaluating an In-Basket exercise and scoring procedures that greatly reduce training and scoring time while retaining adequate reliability and validity. In the first of two studies, an optimal subset of In-Basket items was identified for scoring. Their reliability and concurrent validity were then re-evaluated in a second, cross-validation study. No loss in reliability and little in validity resulted from the scoring-item reduction. In addition, results emerged that shed light on attainable In-Basket reliability and criterion-related validity. Implications for In-Basket use are noted.     

Phenomena of awareness in dementia: Heterogeneity and its implications

Despite much research on the relationship between awareness and dementia little can be concluded concerning their relationship and the role of other factors. It is likely that studies capture different phenomena of awareness. This study aimed at identifying and delineating such variation by analysing data from three questionnaires obtained during the longitudinal study of awareness in 101 people with early-stage dementia. The data concerned awareness in relation to memory, activities of daily living and socio-emotional function. Significant differences in patterns of discrepancies were obtained. This suggests that the awareness phenomena involved were structurally different; and that, in turn, this may reflect variation in the intrinsic linking between awareness and its ‘object’ (different ‘objects’ determining different kinds of judgements). The identification of such differences is necessary so that appropriate methodologies can be applied to the study of awareness in different contexts.     

What constitutes traffic event severity in terms of human danger perception?

This study focuses on the severity gradation of non-collision events. Earlier theoretical work has suggested that a proper severity measure for an event should reflect the risk of personal injury, which is often split into two components, including the risk of a collision and the potential consequences had the collision taken place. While a great number of severity measures have been suggested, most of them fail to address both components, thus resulting in counter-intuitive event gradations and inconclusive outcomes in validation studies. Conversely, it has been shown that human observers often show very good agreement when given a task to rank traffic situations by their severity or level of danger. The aim of this study is to investigate in depth how human judgements of the severity of traffic situations can be expressed by means of objective safety indicators. In this study, a set of video-recorded traffic situations, in which a cyclist passes straight through an intersection while a left or right-turning motor vehicle crosses the cyclist’s path, were analysed. Binary logistic regression was used to develop models assessing the most important traffic severity indicators associated with human feelings of danger. The results showed that the initial conditions of a traffic event, defined as a start of an evasive action, contain the most important information for explaining its severity. Moreover, variables related to both proximity and collision consequences are important and should be integrated into severity measures.     

Young pedestrians' behaviours and risk perception: a pilot study with Italian early adolescents

This study aimed to investigate early adolescents’ mobility, taking into consideration risky pedestrian behaviours around roads and their relationship with independent mobility and risk perception in different traffic situations. The participants were 922 students, males (48%) and females, aged 10–14 and who attended the seventh (51%) and ninth grades in a medium-sized city in southern Italy. They completed an anonymous self-report questionnaire at school, specifically designed for the research. Measures included mode of transport, level of independent mobility, frequency of risky behaviours as a pedestrian and risk perception of these behaviours. Moreover, students were asked to evaluate the risk, their likely behaviour, and likely motives for risky behaviour in a specific traffic scenario concerning a risky road crossing shown on a video. Gender and age differences were taken into consideration, and relationships between risky behaviour as a pedestrian, level of independent mobility and different measures of risk perception (concerning both risk behaviour as a pedestrian and in the video scenario) were investigated. Results showed that risky behaviours while travelling as a pedestrian were more widespread among ninth grade students and those who were more independent. Moreover, a strong relationship between a greater involvement in risky pedestrian behaviours and lower risk perception and a greater tendency to justify risky behaviours were found in the students. Results suggested the implementation of a prevention programme in early adolescence to improve both risk perception in specific traffic situations and the awareness of motives of risky road behaviours.     

The implications of situation and route familiarity for driver-pedestrian interaction at uncontrolled mid-block crosswalks

Most routine daily trips take place along the same route, a fact that previous studies have not investigated together with the repeated situation of conflicting with other road users. Consequently, our study addresses driver behaviour by separating the driving experience into three categories: (i) drivers unfamiliar with the route, (ii) those route-familiar, and (iii) situation-familiar drivers. The specific case of driver-pedestrian interaction at uncontrolled mid-block crosswalks is investigated. A multi-level factorial experiment including (i) crosswalk design (linear sidewalk and curb extension), (ii) driver familiarity, and (iii) pedestrian time gap acceptance (4, 6, and 8 s) was conducted using a driving simulator. Fifty-two participants were divided into four groups and stratified by age, gender, and driving experience. The minimum instantaneous time to collision, post-encroachment time, maximum car deceleration, and maximum car speed were all used as surrogate safety measures (SSM).Route-familiarity led to higher speed, while situation-familiarity positively affected driving behaviour making drivers more inclined to decrease their speed at circa 100 m before a crosswalk. The curb extension layout enhanced pedestrian safety and mitigated any adverse effects due to familiarity, with a particularly relevant impact on SSM at low accepted time gaps for pedestrians. Situation- and route-familiarity treatment protocols lead to different behaviours among drivers, indicating a clear need to account for these two familiarity levels in experiments on safety-related countermeasures.     

Guiding drivers towards safer driving speed: Exploiting visual dominance in speed adaptation

Inappropriate speed is a main cause of accidents. Drivers are often unaware of potential risks due to inadequate speed. To prevent dangerous situations, we need to understand perceptual factors influencing human speed perception. Due to the prominent role of vision in driving, we examined the effect of visuo-spatial stimuli on speed based on the optic flow. While developing an adaptive infrastructure measure to reduce speed, we conducted two consecutive studies, a driving simulator study and a field test to investigate findings further. In both studies, we placed lights on two sides of a highway exit and either illuminated them statically or activated them in a way that they appeared to be moving towards the driver. We expected drivers to slow down more when seeing static light stimuli compared to a baseline without lights. We also expected drivers to decrease speed more in conditions with oncoming lights compared to a baseline, and to static lights, due to distorted speed perception. The first study in a static driving simulator revealed no difference between conditions. In the field test, both static lights and lights moving towards the driver led to a speed reduction compared to a baseline but did not differ from one another. Lights in general led to lower driving speed, potentially due to their warning character, but we found no difference between the light conditions, suggesting that the effect might not be based on the optic flow. Future research should investigate the relationship between driven and perceived speed more closely.     

Discrimination in measures of knowledge monitoring accuracy

Knowledge monitoring predicts academic outcomes in many contexts. However, measures of knowledge monitoring accuracy are often incomplete. In the current study, a measure of students’ ability to discriminate known from unknown information as a component of knowledge monitoring was considered. Undergraduate students’ knowledge monitoring accuracy was assessed and used to predict final exam scores in a specific course. It was found that gamma, a measure commonly used as the measure of knowledge monitoring accuracy, accounted for a small, but significant amount of variance in academic performance whereas the discrimination and bias indexes combined to account for a greater amount of variance in academic performance.     

Different subjective awareness measures demonstrate the influence of visual identification on perceptual awareness ratings

We compare four subjective awareness measures in the context of a visual identification task and investigate quantitative differences in terms of scale use and correlation with task performance. We also analyse the effect of identification task decisions on subsequent subjective reports. Results show that awareness ratings strongly predict accuracy for all scale types, although the type of awareness measure may influence the reported level of perceptual awareness. Surprisingly, the overall relationship between awareness ratings and performance was weaker when participants rated their awareness before providing identification responses. Furthermore, the Perceptual Awareness Scale was most exhaustive only when used after the identification task, whereas confidence ratings were most exhaustive when used before the identification task. We conclude that the type of subjective measure applied may influence the reports on visual awareness. We also propose that identification task decisions may affect subsequent awareness ratings.     

The CORE‐10: A short measure of psychological distress for routine use in the psychological therapies

Background: There is a need for a generic, short, and easy‐to‐use assessment measure for common presentations of psychological distress in UK primary care mental health settings. This paper sets out the development of the CORE‐10 in response to this need. Method: Items were drawn from the CORE‐OM and 10 items were selected according to a combination of usefulness, coverage of item clusters, and statistical procedures. Three CORE‐OM datasets were employed in the development phase: (1) a primary care sample, (2) a sample from an MRC platform trial of enhanced collaborative care of depression in primary care, and (3) a general population sample derived from the Office of National Statistics Psychiatric Morbidity Follow‐up survey. A fourth dataset comprising a sample from an occupational health setting was used to evaluate the CORE‐10 in its standalone format. Results: The internal reliability (alpha) of the CORE‐10 was .90 and the score for the CORE‐10 correlated with the CORE‐OM at .94 in a clinical sample and .92 in a non‐clinical sample. The clinical cut‐off score for general psychological distress was 11.0 with a reliable change index (90% CI) of 6. For depression, the cut‐off score for the CORE‐10 was 13 and yielded sensitivity and specificity values of .92 (CI=.83–1.0) and 0.72 (CI=.60–.83) respectively. Conclusion: The CORE‐10 is an acceptable and feasible instrument that has good psychometric properties and is practical to use with people presenting with common mental health problems in primary care settings.