Market Structure and Entry: Where's the Beef?.

We study the effects of market structure on entry using data from the UK fast food (counter-service burger)industry over the years 1991-1995. Over this period, the market can be characterized as a duopoly. We find that market structure matters greatly: for both firms, rival presence increases the probability of entry. We control for market specific time-invariant unobservable and their correlation with existing outlets of both firms through a variety of methods.LEARNING ; MARKET ; DUOPOLY

Multiproduct Firms and Product Differentiation: a Survey.

We start the survey by reviewing the implications of horizontal and vertical product differentiation on market structure under the assumption of single-product firms. Then, we analyze the main results of the multi-product firm models, both when variants are assumed differentiated in vertical attributes only and when variants are assumed differentiated in two dimensions (vertical and horizontal). Finally, we review the empirical literature about the discrete-choice models of product differention.COMPETITION ; MARKET ; PRODUCTION DIVERSIFICATION

The use of simulation in the design of a road transport incident detection algorithm

Automatic incident detection is becoming one of the core tools of urban traffic management, enabling more rapid identification and response to traffic incidents and congestion. Existing traffic detection infrastructure within urban areas (often installed for traffic signal optimization) provides urban traffic control systems with a near continuous stream of data on the state of traffic within the network. The creation of a simulation to replicate such a data stream therefore provides a facility for the development of accurate congestion detection and warning algorithms. This paper describes firstly the augmentation of a commercial traffic model to provide an urban traffic control simulation platform and secondly the development of a new incident detection system (RAID-Remote Automatic Incident Detection), with the facility to use the simulation platform as an integral part of the design and calibration process. A brief description of a practical implementation of RAID is included along with summary evaluation results

Do British wind generators behave strategically in response to the Western Link interconnector?

In Britain, the key source of renewable generation is wind, most abundant on the west coast of Scotland, where there is relatively little demand. For this reason, an interconnector, the Western Link, was built to take electricity closer to demand. When the Link is operating, payments by National Grid to constrain wind farms not to produce will be lower, we may predict, since fewer or less restrictive constraints need be imposed. But the Link has not been working consistently. We empirically estimate the link’s value. Focusing on the three most recent episodes of outage, starting on 4th May 2018 up to 25th September 2019, our essential approach is to treat these outages as a natural experiment using hourly data. Our results reveal that the Link had an important role in costs saved and price constrained and MWh curtailed reductions. We estimate a cost-saving of almost £30m. However, the saving appears to drop over time, so we investigate wind farms’ behavior. We find that wind farms behave strategically since the accuracy of wind forecasting depends on the relevant prices impacting their earnings

Building the economic evidence case for social prescribing

Understanding the economic impact of social prescribing remains an urgent priority for the National Academy of Social Prescribing (NASP). As yet it is unclear how much data exists within the different systems to enable economic analyses of the impact of social prescribing schemes to be conducted. The complexity in understanding the economic impact of social prescribing—and indeed all non-clinical community-based approaches to health—is compounded by the multisector nature of social prescribing. Furthermore, a variety of approaches are being used to test similar but different understandings of both cost and value, including social value, cost, benefit and economic value. There are a growing range of reports and peer-reviewed publications that focus on the impact of social prescribing on health and social care demand, some of which have economic analyses and some which remain as potential data sets for economic analyses. At least one third of all outcomes (if not more) are directly related to the social determinants of health1,2 (SDH) which are not taken into account with economic analysis focused only on health service usage. This range of outcomes experienced by service users2-4 is driving many researchers to conduct economic analyses that attempt to assign value to outcomes beyond the health sector, for instance using social return on investment (SROI) and proxy values. Other researchers have discussed the evolution in economic analyses at length and suggest additional components to existing methodologies, e.g., multi criteria decision analysis (MCDA) to account for additional complexity of social prescribing5. Further developments are also being trialled such as the Wellbeing-adjusted Life Years (WELLBY) to understand the economic value attached to wellbeing6, as opposed to the Quality Adjusted Life Years (QALY), which reports the economic value of quality of life. We are entering an era of providing personalised support to people in integrated and multidisciplinary systems with different local population needs. As such, there is a need to evolve the approaches to determining cost and value of social prescribing, and to reach agreements on methodologies that all sectors are willing to accept as sound approaches. Furthermore, as discussed by McDaid and colleagues in 2019 7, there is a need to move beyond the immediate benefits of social prescribing and to explore the longer-term benefits of sustained engagement in non-clinical activities and provision of support to address issues linked to the SDH. This would enable more data to inform the preventative role and economic impact that social prescribing may have, which is currently an evidence gap. This rapid scoping review was commissioned by NASP and additional roundtables were supported by the National Centre for Creative Health and UKRI/AHRC’s ‘Mobilising Community Assets to Tackle Health Inequalities’ research programme (led by University College London). It aims to provide an update to the first economic evidence review from NASP and explore economic data and health and social care usage data in more detail. This rapid scoping review aims to ascertain: What the current literature indicates in terms of cost or value of social prescribing schemes or parts of the social prescribing scheme. If there are potential data sets that report the impact of social prescribing on health service usage that could have economic analysis applied to them. Stakeholder opinions on the methodological approaches for creating the current economic evaluation evidence base for social prescribing and potential future developments that are needed. How these findings can inform a larger programme of research that is needed to establish the economic impact and value of social prescribing across all relevant sectors in the community. As this report contains three separate elements to it, each element will be reported with methods and results, and then key themes will be brought together with recommendations

Jazz Baby / music by M. K. Jerome; words by Blanche Merrill

Cover: drawing of Caucasian couples dancing in at a Ball; Publisher: Waterson Berlin and Snyder Co. (New York)https://egrove.olemiss.edu/sharris_c/1167/thumbnail.jp

Antibiotics for exacerbations of asthma.

BACKGROUND: Asthma is a chronic respiratory condition that affects over 300 million adults and children worldwide. It is characterised by wheeze, cough, chest tightness, and shortness of breath. Symptoms typically are intermittent and may worsen over a short time, leading to an exacerbation. Asthma exacerbations can be serious, leading to hospitalisation or even death in rare cases. Exacerbations may be treated by increasing an individual's usual medication and providing additional medication, such as oral steroids. Although antibiotics are sometimes included in the treatment regimen, bacterial infections are thought to be responsible for only a minority of exacerbations, and current guidance states that antibiotics should be reserved for cases in which clear signs, symptoms, or laboratory test results are suggestive of bacterial infection. OBJECTIVES: To determine the efficacy and safety of antibiotics in the treatment of asthma exacerbations. SEARCH METHODS: We searched the Cochrane Airways Trials Register, which contains records compiled from multiple electronic and handsearched resources. We also searched trial registries and reference lists of primary studies. We conducted the most recent search in October 2017. SELECTION CRITERIA: We included studies comparing antibiotic therapy for asthma exacerbations in adults or children versus placebo or usual care not involving an antibiotic. We allowed studies including any type of antibiotic, any dose, and any duration, providing the aim was to treat the exacerbation. We included parallel studies of any duration conducted in any setting and planned to include cluster trials. We excluded cross-over trials. We included studies reported as full-text articles, those published as abstracts only, and unpublished data. DATA COLLECTION AND ANALYSIS: At least two review authors screened the search results for eligible studies. We extracted outcome data, assessed risk of bias in duplicate, and resolved discrepancies by involving another review author. We analysed dichotomous data as odds ratios (ORs) or risk differences (RDs), and continuous data as mean differences (MDs), all with a fixed-effect model. We described skewed data narratively. We graded the results and presented evidence in 'Summary of findings' tables for each comparison. Primary outcomes were intensive care unit/high dependence unit (ICU/HDU) admission, duration of symptoms/exacerbations, and all adverse events. Seconday outcomes were mortality, length of hospital admission, relapse after index presentation, and peak expiratory flow rate (PEFR). MAIN RESULTS: Six studies met our inclusion criteria and included a total of 681 adults and children with exacerbations of asthma. Mean age in the three studies in adults ranged from 36.2 to 41.2 years. The three studies in children applied varied inclusion criteria, ranging from one to 18 years of age. Five studies explicitly excluded participants with obvious signs and symptoms of bacterial infection (i.e. those clearly meeting current guidance to receive antibiotics). Four studies investigated macrolide antibiotics, and two studies investigated penicillin (amoxicillin and ampicillin) antibiotics; both studies using penicillin were conducted over 35 years ago. Five studies compared antibiotics versus placebo, and one was open-label. Study follow-up ranged from one to twelve weeks. Trials were of varied methodological quality, and we were able to perform only limited meta-analysis.None of the included trials reported ICU/HDU admission, although one participant in the placebo group of a study including children with status asthmaticus experienced a respiratory arrest and was ventilated. Four studies reported asthma symptoms, but we were able to combine results for only two macrolide studies of 416 participants; the MD in diary card symptom score was -0.34 (95% confidence interval (CI) -0.60 to -0.08), with lower scores (on a 7 point scale) denoting improved symptoms. Two macrolide studies reported symptom-free days. One study of 255 adults authors reported the percentage of symptom-free days at 10 days as 16% in the antibiotic group and 8% in the placebo group. In a further study of 40 children study authors reported significantly more symptom-free days at all time points in the antibiotic group compared with the usual care group. The same study reported the duration in days of the index asthma exacerbation, again favouring the antibiotic group. One study of a penicillin including 69 participants reported asthma symptoms at hospital discharge; the between-group difference for both studies was reported as non-significant.We combined data for serious adverse events from three studies involving 502 participants, but events were rare; the three trials reported only 10 events: five in the antibiotic group and five in the placebo group. We combined data for all adverse events (AEs) from three studies, but the effect estimate is imprecise (OR 0.99, 95% CI 0.69 to 1.43). No deaths were reported in any of the included studies.Two studies investigating penicillins reported admission duration; neither study reported a between-group difference. In one study (263 participants) of macrolides, two participants in each arm were reported as experiencing a relapse, defined as a further exacerbation, by the six-week time points. We combined PEFR endpoint results at 10 days for two macrolide studies; the result favoured antibiotics over placebo (MD 23.42 L/min, 95% CI 5.23 to 41.60). One study in children reported the maximum peak flow recorded during the follow-up period, favouring the clarithromycin group, but the confidence interval includes no difference (MD 38.80, 95% CI -11.19 to 88.79).Grading of outcomes ranged from moderate to very low quality, with quality of outcomes downgraded for suspicion of publication bias, indirectness, imprecision, and poor methodological quality of studies. AUTHORS' CONCLUSIONS: We found limited evidence that antibiotics given at the time of an asthma exacerbation may improve symptoms and PEFR at follow-up compared with standard care or placebo. However, findings were inconsistent across the six heterogeneous studies included, two of the studies were conducted over 30 years ago and most of the participants included in this review were recruited from emergency departments, limiting the applicability of findings to this population. Therefore we have limited confidence in the results. We found insufficient evidence about several patient-important outcomes (e.g. hospital admission) to form conclusions. We were unable to rule out a difference between groups in terms of all adverse events, but serious adverse events were rare

Jazz Baby / music by M. K. Jerome; words by Blanche Merrill

Cover: drawing of well-dressed Caucasian couples dancing; Publisher: Waterson Berlin and Snyder Co. (New York)https://egrove.olemiss.edu/sharris_c/1161/thumbnail.jp