Assaf Botzer

Numerous papers have demonstrated that by using a varying coefficients model (VCM), researchers can unveil patterns of interactions between variables that could otherwise remain hidden if using the more popular regression model with an interaction term. Hence, one would expect high acceptance of the VCM as a tool for studying statistical interactions in datasets. Yet, the current paper shows that the VCM is still struggling to migrate from journals in which methods are presented to journals in which methods are utilized. First, a search in Google Scholar with the phrase “varying coefficients” returned ~79,200 results in comparison to returning ~2,710,000 results with the phrase “interaction term”. Second, a bibliometric analysis of publications with the VCM showed that in many research domains, there were more publications with the VCM in journals on methods than publications with the VCM in journals for empirical investigations. Economics and environmental studies stood out with many more publications with the VCM in empirical journals than in journals on statistical methods. The gap between the high acclaims of the VCM in the statistical literature and its low utilization rate in practice should be of concern to the research community. The possible reasons for this gap and its potential remedies are discussed.

Teleoperation services are expected to operate on-road and often in urban areas. In current teleoperation applications, teleoperators gain a higher viewpoint of the environment from a camera on the vehicle’s roof. However, it is unclear how this viewpoint compares to a conventional viewpoint in terms of safety, efficiency, and mental workload. In the current study, teleoperators (n = 148) performed driving tasks in a simulated urban environment with a conventional viewpoint (i.e., the simulated camera was positioned inside the vehicle at the height of a driver’s eyes) and a higher viewpoint (the simulated camera was positioned on the vehicle roof). The tasks required negotiating road geometry and other road users. At the end of the session, participants completed the NASA-TLX questionnaire. Results showed that participants completed most tasks faster with the higher viewpoint and reported lower frustration and mental demand. The camera position did not affect collision rates nor the probability of hard braking and steering events. We conclude that a viewpoint from the vehicle roof may improve teleoperation efficiency without compromising driving safety, while also lowering the teleoperators’ mental workload.

The current experiment is part of an ongoing feasibility testing of grip force as a measure of stress in joystick-controlled tasks. In a previous experiment, we showed that mean grip force of a group of students was higher under a stress manipulation, and higher than of another group of students with no stress manipulation. In the current experiment, we tested if we could identify greater grip force under stress, per individual. Fourteen male participants performed tracking tasks on trials with and without a stress manipulation. After the experiment, we computed the mean grip force of each participant in several intervals to test how soon (if at all) his mean grip force on the trials with the stress manipulation had become significantly higher than his mean grip force on the trials without the stress manipulation. In ∼31% of the comparisons we were able to detect higher grip force with than without the stress manipulation after 5 seconds through the trials. Other detections of greater grip force took longer, but no longer than 30 sec. However, we could not find significant changes in grip force in certain comparisons for six individuals, and in none of the comparisons for four individuals. The sources and extent of these limitations of grip force as a measure of stress should be explored in future studies. The current experiment added support to the feasibility of using grip force as a measure of stress in joystick-controlled tasks and pointed to the next necessary steps in evaluating its feasibility.

The current experiment is part of an ongoing feasibility testing of grip force as a measure of stress in joystick-controlled tasks. In a previous study, we showed that grip force of one group was higher under a stress manipulation, and higher than of another group without stress manipulation. In the current experiment, we tested if we could identify greater grip force under stress, per individual. Fourteen participants performed tracking tasks in trials with and without a stress manipulation. We computed the mean grip force of each participant in several intervals to test how soon (if at all) his grip force in the trials with the stress manipulation had become significantly higher than in the trials without the stress manipulation. In ∼31% of the comparisons, we were able to detect higher grip force with than without the stress manipulation after 5 s through the trials. Other detections of greater grip force took longer, but no longer than 30 s. However, not all participants gripped significantly harder during the stress manipulation. The current experiment added support to the feasibility of using grip force as a measure of stress in joystick-controlled tasks and pointed to the next necessary steps in evaluating its feasibility.