Multistage Selection Research Articles

Risk factors underlining reproductive performance in smallholder beef cattle herds of South Africa

Improving the historically low reproductive performance of beef cattle in smallholder systems is essential for its productivity and profitability. Therefore, identifying and addressing risk factors associated with low performance in this system present an opportunity for improvement. The study aimed to evaluate the effect of animal and management risk factors on pregnancy rate (PR), fetal and calf loss (FC), calving interval (CI) and days open (DO) in smallholder beef cattle farms. A multi-stage selection approach was conducted in five provinces of South Africa. Cow records (3694) collected from 40 smallholder herds over two years (2018–2019) were analysed. Data on animal and herd management factors including body condition score (BCS), cow age class, breed type, lactation status, culling old/non-productive cows, record-keeping, and breeding and calving seasons were recorded. The GLIMMIX procedure was computed to determine risk factors associated with performance indicators (PR, FC, CI and DO). Risk factors highly associated with performance were breed type, BCS, cow-age class and breeding/calving season (P ≤ 0.05). Indicators FC, DO and CI increased with decreased BCS, autumn calving seasons, and in first calvers and aged cows. Whereas, PR increased with increasing odds of BCS and breeding seasons between December-March, November-February and January-March. Optimizing reproductive performance in smallholder beef cattle herds may involve managing cow body condition, breeding with adapted genotypes and synchronizing breeding with favourable seasons. Therefore, record keeping and regular monitoring of herd nutrition, climate and breed performance may be significant in improving reproductive performance in smallholder herds.

Polymorphisms in the Growth Hormone Gene and Their Association with Pre-pullet Body Weight in Kuttanad Ducks of Kerala, India

Background: Kuttanad ducks are dual purpose native ducks found in Kerala state of India. Identification of single nucleotide variations in candidate genes like growth hormone gene and exploring their association with body weight at grower and pre-pullet stages is essential for the marker assisted selection of breeder ducks for genetic improvement. Methods: Genomic DNA was extracted from blood samples collected from 101 Kuttanad ducks. PCR-amplification of two duck growth hormone gene (dGH) loci viz, exon 3 and partial intron 3 (227 bp), exon 5 and partial intron 4 (366 bp) were undertaken using custom-synthesised primers. The 366 bp region was genotyped using Single Strand Conformation Polymorphism. The 227 bp region was genotyped using DNA pooling assay to yield a 139 bp product for subsequent High-Resolution Melting analysis. The association of dGH genotypic variants for these loci with fortnightly body weight at pre-pullet stages up to 16 weeks of age was analysed. Result: In the 366 bp fragment, GG and GA genotypes were revealed with one novel SNP (g 74G greater than A). The GG homozygotes had significantly higher body weight at all stages from two to 14 weeks of age (p≤0.01). A novel SNP (g 71A greater than G) was revealed at the 139 bp locus within the 227 bp region with three genotypes viz., AA, AG and GG. The GG homozygotes had significantly higher body weight at six, 14 and 16 weeks of age (p≤0.05). The study revealed that dGH polymorphic loci have jointly contributed to the variation in growth and hence can be used as markers for the primary selection of growers at sixth week of age followed by their secondary selection at 14-16 weeks of age during the multi-stage selection programmes for breeder ducks.

Factors determining farmers’ adoption of cultural practices for forest resources conservation in Delta State, Nigeria

ABSTRACT Studies on conservation of forest resources abound but the application of cultural practices is being neglected. The use of the logit regression model in identifying the factors that influenced the adoption of these cultural practices was a milestone in this work. The goal of the study was to identify existing cultural practices of conservation and factors that influenced its adoption. Key informants for the study were obtained using multi-stage selection techniques. Information on cultural practices, forest resources conserved by these practices and groups within the community responsible for implementing these practices were obtained using a structured questionnaire and interview schedule. Descriptive statistics and a logistic regression model were used. The study bared that males (70.4%) dominated. The practice of sacred grooves, forbidden forest resources, festive harvesting, ancestral beliefs and restriction from felling trees of ancestral origin was used in conserving snakes, crocodiles, Millicia excelsa, Achatina achatina, Tyto alba, Neuboudia laevis, Irvingia wombulu in the communities. The factors influencing the adoption of these practices were education, age of the respondent, native of the community and religion. The traditional head, traditional executives, chief priest and sometimes, the whole community enforced and implemented these beliefs and proscribed penalties for defaulters. Cultural practices that support the wise use of resources from the forest are still in existence and effective. The collaboration of the State Forestry division with these communities in harnessing their cultural practices is vital to the quest of conserving these diverse species in the forest.

Multi-arm multi-stage (MAMS) randomised selection designs: impact of treatment selection rules on the operating characteristics

BackgroundMulti-arm multi-stage (MAMS) randomised trial designs have been proposed to evaluate multiple research questions in the confirmatory setting. In designs with several interventions, such as the 8-arm 3-stage ROSSINI-2 trial for preventing surgical wound infection, there are likely to be strict limits on the number of individuals that can be recruited or the funds available to support the protocol. These limitations may mean that not all research treatments can continue to accrue the required sample size for the definitive analysis of the primary outcome measure at the final stage. In these cases, an additional treatment selection rule can be applied at the early stages of the trial to restrict the maximum number of research arms that can progress to the subsequent stage(s).This article provides guidelines on how to implement treatment selection within the MAMS framework. It explores the impact of treatment selection rules, interim lack-of-benefit stopping boundaries and the timing of treatment selection on the operating characteristics of the MAMS selection design.MethodsWe outline the steps to design a MAMS selection trial. Extensive simulation studies are used to explore the maximum/expected sample sizes, familywise type I error rate (FWER), and overall power of the design under both binding and non-binding interim stopping boundaries for lack-of-benefit.ResultsPre-specification of a treatment selection rule reduces the maximum sample size by approximately 25% in our simulations. The familywise type I error rate of a MAMS selection design is smaller than that of the standard MAMS design with similar design specifications without the additional treatment selection rule. In designs with strict selection rules - for example, when only one research arm is selected from 7 arms - the final stage significance levels can be relaxed for the primary analyses to ensure that the overall type I error for the trial is not underspent. When conducting treatment selection from several treatment arms, it is important to select a large enough subset of research arms (that is, more than one research arm) at early stages to maintain the overall power at the pre-specified level.ConclusionsMulti-arm multi-stage selection designs gain efficiency over the standard MAMS design by reducing the overall sample size. Diligent pre-specification of the treatment selection rule, final stage significance level and interim stopping boundaries for lack-of-benefit are key to controlling the operating characteristics of a MAMS selection design. We provide guidance on these design features to ensure control of the operating characteristics.

Best Business Models for the Fast-Moving Consumer Goods Sector: Patterns for Innovation

Mankind’s consumption exceeds our natural resources, so among other things, the development of new business models at the company level is needed. This paper aims to generate systematic business model innovations in the field of fast-moving consumer goods using business model patterns to foster sustainability. Based on a literature search, the most relevant patterns for the industry are identified as part of a multi-stage selection process that is based on the value generated by the patterns. Expert surveys are the central instrument for data collection. Here, the connection of the patterns to the strategy is central. The result is a list of relevant patterns, which includes patterns from completely external industries. This is the first evaluation of its kind, which shows that patterns focusing only on the circular economy are not enough to succeed and, therefore, break the scientific paradigm.

Promoting Learning About Local Food Security by Applying Environmental Education Processes to People in Central Part of Thailand

The objective of this research is twofold: firstly, to examine the level of local food security and the community members’ understanding of environmental education; and secondly, to develop a model that enhances local food security by implementing the environmental education practices of the community residents. Utilized mixed-methods research. Data were gathered via a questionnaire, a group discussion, and a workshop. A total of 378 respondents were chosen for the questionnaire using multi-stage selection, while 45 respondents were chosen using purposive sampling. Furthermore, a total of 32 community volunteers were extended an invitation to participate in the workshop. This study included descriptive statistics and content analysis. The findings indicate that the target communities have an average perception level of 3.19 regarding local food security, while their knowledge about the environment is at a high level of 4.01. The study identifies five key components for establishing local food security, namely: (1) learning local food identity; (2) inheriting local wisdom; (3) transmitting local food knowledge; (4) managing sources of local food; and (5) building local networks.

Learning Fair Policies for Multi-Stage Selection Problems from Observational Data

We consider the problem of learning fair policies for multi-stage selection problems from observational data. This problem arises in several high-stakes domains such as company hiring, loan approval, or bail decisions where outcomes (e.g., career success, loan repayment, recidivism) are only observed for those selected. We propose a multi-stage framework that can be augmented with various fairness constraints, such as demographic parity or equal opportunity. This problem is a highly intractable infinite chance-constrained program involving the unknown joint distribution of covariates and outcomes. Motivated by the potential impact of selection decisions on people’s lives and livelihoods, we propose to focus on interpretable linear selection rules. Leveraging tools from causal inference and sample average approximation, we obtain an asymptotically consistent solution to this selection problem by solving a mixed binary conic optimization problem, which can be solved using standard off-the-shelf solvers. We conduct extensive computational experiments on a variety of datasets adapted from the UCI repository on which we show that our proposed approaches can achieve an 11.6% improvement in precision and a 38% reduction in the measure of unfairness compared to the existing selection policy.

Onshore power supply–trends in research studies

Restrictive regulations introduced by the European Parliament and the United Nations have forced the seaport authorities to reach net zero gas emissions by 2030. An important source of pollution emitted in ports involves exhaust gas emissions from ships powered by ship engines while they are berthed in seaports. One of the ways to reduce the level of pollution and nuisance caused by ship engines is to equip ships with Onshore Power Supply (OPS). Unfortunately, still few ports can boast this type of systems at their quays. There are many publications devoted to the analysis of this phenomenon in the technical and engineering terms, but a significant part also concerns the economic, financial, logistic and organizational aspects. The aim of this research is to identify the directions of development as for research into OPS, to organize the terminology devoted to OPS, and to define scientific disciplines of research in the field of OPS. This research was conducted on the basis of the data mining method using the Scopus, EBSCO and Web of Science databases, applying the multi-stage selection of criteria. The research results may provide an interesting material for scientists to identify the gaps of research regarding OPS.

Surgical management of recurrent instability following Latarjet procedure - A systematic review of salvage procedures.

Failed Latarjet procedures pose a surgical challenge due to complex anatomical issues. This systematic review investigates salvage techniques for recurrent instability following a Latarjet procedure. A search was conducted on MEDLINE and PubMed Central following the methodology registered to International Prospective Register of Systematic Reviews. Inclusion criteria focused on identifying revision procedures following a Latarjet procedure. Exclusion criteria filtered out irrelevant studies, such as those focused on Bankart procedures. After a multistage selection process, 10 eligible studies were included for data extraction. The most frequently utilized technique for salvage was variations of the Eden-Hybinette procedure. Complications associated with these salvage procedures include graft-related problems and donor site morbidity. Patients reported significant improvements in multiple patient-reported outcome scores, and multiple studies indicated high rates of return to sports activities. However, it is noteworthy that there remains an average recurrence rate of 7%. The review emphasizes the limited therapeutic options available largely due to shoulder anatomy alterations. Despite promising trends in patient-reported outcomes, recurrence remains possible post-salvage surgeries. Addressing recurrent instability after a Latarjet procedure continues to be a unique surgical challenge. However, this systematic review highlights encouraging indications, with positive trends evident in patient-reported outcomes.

The Impact of Covid-19 on the Work Practices of Teaching and Administrative Staff in Public Universities in Ghana: A Qualitative Case Study

The outbreak of COVID-19 revealed the unpreparedness of many people and institutions to deal with crisis situation. The pandemic has brought about changes in the operations of both teaching and non-teaching personnel in institutions. The objective of this study was to explore the aftermath impact and challenges that the Covid-19 pandemic has had on the work of faculty members and administrators in a public university context. Employing a holistic case study design using a qualitative research approach, the study recruited 54 senior members (teaching and non-teaching) from five colleges, 18 Faculties/schools, and nine directorates senior members using a multi-stage selection techniques. The study found key challenges of administrative staff due to the pandemic to include staff unreceptiveness, role ambiguity, supervision issues, lesson plan and delivery issues, assessment issues, poor trainee disposition, trainee unpreparedness, among others. Participants also intimated that the pandemic has resulted in shifts to remote learning, requiring administrative support in the provision of Information communication Technology (ICT) services to ensure students’ access to the necessary technology, among others. A majority further mentioned measures such as strengthening institutional alert and response capacities through the creation of pandemic task forces, diversifying university academic programmes to attract massive student enrolments support, institutionalizing the use of blended learning modes among others to mitigate the adverse effects of future pandemics. These measures, according to the interviewees have been effective especially because they have resulted in flexible work and learning, which helps to improve institutional productivity and the finances of the university in the face of dwindling government subventions. The study concluded that the COVID-19 pandemic has brought about many challenges for teaching and administrative work in public universities and so these universities have to put in place effective measures to mitigate the adverse effects of future pandemics.

A Scoping Review on Analysis of the Barriers and Support Factors of Open Data

Background: Using personal data as Open Data is a pervasive topic globally, spanning various sectors and disciplines. Recent technological advancements, particularly in artificial intelligence and algorithm-driven analysis, have significantly expanded the capacity for the automated analysis of vast datasets. There’s an expectation that Open Data analysis can drive innovation, enhance services, and streamline administrative processes. However, this necessitates a legally and ethically sound framework alongside intelligent technical tools to comprehensively analyze data for societal benefit. Methodology: A systematic review across seven databases (MEDLINE, CINAHL, BASE, LIVIVO, Web of Science, IEEExplore, and ACM) was conducted to assess the current research on barriers, support factors, and options for the anonymized processing of personal data as Open Data. Additionally, a supplementary search was performed in Google Scholar. A total of n=1192 studies were identified, and n=55 met the inclusion criteria through a multi-stage selection process for further analysis. Results: Fourteen potential supporting factors (n=14) and thirteen barriers (n=13) to the provision and anonymization of personal data were identified. These encompassed technical prerequisites as well as institutional, personnel, ethical, and legal considerations. These findings offer insights into existing obstacles and supportive structures within Open Data processes for effective implementation.

Digital participation in traumatic brain injury: scoping review about assessment tools for computer-mediated communication

BackgroundIndividuals with chronic traumatic brain injury (TBI) are often affected by communication disorders which might have an impact on their social participation. Due to possible cognitive and communicative disabilities, as well as impairments of social cognitive skills, individuals with TBI have been observed to exhibit difficulties in maintaining and establishing social relationships, resulting in a greater risk of social isolation. This applies to both in-person as well as computer-mediated communication (CMC), which is considered an integral part of everyday life. Research on digital participation in the TBI population has focused on the possible challenges and barriers, but also on the benefits of CMC for social interactions. Guidelines from professional societies recommend questionnaires and checklists for assessing restrictions of communicative participation (e.g., ASHA, INCOG). However, there is no overview of whether the available instruments can capture digital aspects of participation or social media use in TBI.AimIn this scoping review, following the PRISMA criteria, we aimed to provide an overview over currently available instruments that help assess CMC use as a measure of digital participation in the TBI population.MethodThe databases Web of Science Core Collection, Ovid, PsycInfo and Psyndex were screened for publications between the years 2013 and 2023 with relevant search terms referring to social participation, assessment tools, CMC and the target group, in order to find suitable tools to assess digital participation in individuals with TBI. In a multistage selection process following the PRISMA criteria, the instruments found were examined in terms of items that assess digital participation. The outcome of the review is an overview of the status quo of potentially available instruments that capture aspects of CMC.ResultsFollowing a screening on title/abstract and full-text level, a total of 10 studies could be identified that present assessment tools that evaluate CMC use as a measure of digital participation in the TBI population. Said studies were analyzed and compared in terms of content according to the selected parameters.ConclusionDigital participation is an important aspect of everyday lives for individuals with TBI. Therefore, CMC should be an integral part of rehabilitation. The existing appropriate questionnaires uncovered in the current study should therefore be applied routinely to detect impairments in CMC and digital participation. Overall, however, there is still a great need for research in the field of CMC, both regarding methods for measuring digital participation disorders as well as resources.Systematic Review Registrationhttps://www.germanistik.uni-muenchen.de/forschung/proj_gl/review_participation_tbi.pdf.

Family Structure and Parents’ Educational Levels as Correlates of Lower Primary School Pupils’ Academic Achievement in Social Studies in Osun State, Nigeria

The paper investigated the educational backgrounds of parents of elementary students in Osun state, Nigeria. It aimed to analyze the connection between parents' educational attainment and the educational performance of elementary pupils in the subject of Social Studies. Additionally, the work explored the relationship between family state and the educational achievement of elementary pupils. The investigation employed a descriptive correlational survey research design. The target study comprised pupils aged 5-8 years old and their parents residing in Osun State. The sample population consisted of 300 students and 300 parents, selected through a multistage selection technique. From every selected school, twenty (20) children were chosen using a simple random selection procedure, and all parents of the chosen pupils were purposefully employed for the study, comprising 300 pupils and 300 parents who comprised the study's sample. The two research instruments were “Questionnaire on Family Structure and Parents' Educational Levels” (QFSPEL) and “Pupils' Previous Terms Results in Social Studies” (PPTRSS). The data collected were analyzed statistically using frequency, percentage, and “Pearson Product Moment Correlation (PPMC) methods” The research findings shows that the degree of lower primary school children' family structure is very high in Osun State, at 78.5%. The findings found that the level of education of lower primary school children’s parents was high in Osun State, at 58.1% in the study results, a significant and positive correlation (r = 0.885; p < 0.05) between parents' educational levels and the academic achievement of lower primary school students in Social Studies within the study area. On the other hand, the study did not find a significant correlation between family settings and the educational abilities of lower elementary children of study area in Social Studies (r = 1.978; p > 0.05).

Poverty and Frustration as Predictor of Domestic Violence among Sandwich Students

The prevalence of domestic violence in Nigeria remains alarmingly high, exhibiting no discernible indications of decline. Prevalence of this phenomenon is observed among couples irrespective of their age, ethnic background, religious affiliation, or socioeconomic standing. This study aims to investigate the relationship between poverty and dissatisfaction as predictors of spousal violence among sandwich students. The research employed a descriptive design of the ex-post-facto kind. A multi-stage selection procedure was employed to pick a sample of 120 respondents from three departments. The participants were assessed using appropriate standardized measures (instruments) and the collected data were subjected to statistical analysis utilizing the percentage and Pearson Product Moment Correlation (PPMC) and Multiple Regression techniques at a significance level of 0.05. Hence, in light of the research indicating a significant correlation between poverty and domestic violence, it is suggested that counseling professionals and psychologists should enhance their endeavors to organize seminars for student couples.

Transforming Clinical Information Systems: Empowering Healthcare through Telemedicine, Data Science, and Artificial Intelligence Applications.

In this synopsis, the editors of the Clinical Information Systems (CIS) section of the IMIA Yearbook of Medical Informatics overview recent research and propose a selection of best papers published in 2022 in the CIS field. The editors follow a systematic approach to gather relevant articles and select the best papers for the section. This year, they updated the query to incorporate the topic of telemedicine and removed search terms related to geographic information systems. The revised query resulted in a larger number of identified papers, necessitating the appointment of a third section editor to handle the increased workload. The editors narrowed the initial pool of articles to 15 candidate papers through a multi-stage selection process. At least seven independent reviews were collected for each candidate paper, and a selection meeting with the IMIA Yearbook editorial board led to the final selection of the best papers for the CIS section. The query was carried out in mid-January 2023 and retrieved a deduplicated result set of 5,206 articles from 1,500 journals. This year, 15 papers were nominated as candidates, and four were finally selected as the best papers in the CIS section.Including telemedicine in the query resulted in a substantial increase in the number of papers found. The analysis highlights the growing convergence between clinical information systems and telemedicine, with mobile health (mHealth) technologies and data science applications gaining prominence. The selected candidate papers emphasize the practical impact of research efforts, focusing on patient-centric outcomes and benefits, including intelligent mobile health monitoring systems and AI-assisted decision-making in healthcare. Looking ahead, the field of CIS is expected to continue evolving, driven by advances in telemedicine, mHealth technologies, data science, and AI integration, leading to more efficient, patient-oriented, and intelligent healthcare systems and overall improvement of global healthcare outcomes.

Effect of Fulani Herdsmen Grazing Activities on Food Crop Production among Farm Youth in Nigeria

This study investigated the effect of herdsmen grazing activities on food crop production among farm youth in Nigeria. Data were collected from 120 farm youth through a structured interview schedule with a multi-stage selection process. Data analysis was done using appropriate statistics. The results reveal mean age and experience in farming of the youth were 29.03± 1.9 years and 11.11 ±7.22 years, respectively. Many (69.2%) of them were male with at least 77.5% having primary school education, and 60.88% had experienced the occurrence of Fulani herdsmen grazing activities in the past three years. In addition, 98.3 percent experienced a high effect of Fulani herdsmen grazing activities on their food crop production. Verbal warning (mean = 2.96) ranked highest among coping strategies adopted by farm youth, followed by local security (mean = 1.94) among others. At p<0.01, the perception of the grazing activities (r = 0.595), experience in farming (r = 0.411), and coping strategies (r = 0.446) had a substantial association with the effect of the Fulani herdsmen grazing activities on food crop production. The study then concluded that the Fulani herdsmen grazing activities had a high effect on the food crop production of the farm youth.

Impact of dialectic behaviour therapy and assertiveness training on the mental health of socially stressed senior secondary students

Social stress resulting from substance abuse is a growing global concern. It is linked to mental health with psychosocial challenges faced by a large number of the populace in Nigeria. It is worrisome, especially among students in senior secondary schools in Port-Harcourt Metropolis. Thus, this research examined ‘Dialectic Behaviour Therapy and Assertiveness Training’ in managing psychosocial mental health problems of senior secondary school students who abuse substances in the Port-Harcourt metropolis. Tests before and after the study had a population of 9.650 students and employed quasi-experimental procedures. For the study, a 75-student sample from senior secondary school 2, comprised of 37 males and 38 females, was selected utilizing a multistage selection approach. Car, Relax, Alone, Forget, Family/Friends Trouble, Edinburg Mental well-being scale, and Social Phobia Inventory were the instruments utilized to collect the data. Findings revealed significant differences in the psychosocial problems of adolescents in senior secondary schools because of the interventions, however, dialectic behaviour therapy made more impact in the reduction of adolescents’ social stress though both treatments had a significant impact. Keywords: Assertiveness training, dialectic behaviour therapy, mental health, social stress, substance abuse

Identification of Novel Risk Variants of Non-Syndromic Cleft Palate by Targeted Gene Panel Sequencing.

Non-syndromic cleft palate (ns-CP) has a genetically heterogeneous aetiology. Numerous studies have suggested a crucial role of rare coding variants in characterizing the unrevealed component of genetic variation in ns-CP called the "missing heritability". Therefore, this study aimed to detect low-frequency variants that are implicated in ns-CP aetiology in the Polish population. For this purpose, coding regions of 423 genes associated with orofacial cleft anomalies and/or involved with facial development were screened in 38 ns-CP patients using the next-generation sequencing technology. After multistage selection and prioritisation, eight novel and four known rare variants that may influence an individual's risk of ns-CP were identified. Among detected alternations, seven were located in novel candidate genes for ns-CP, including COL17A1 (c.2435-1G>A), DLG1 (c.1586G>C, p.Glu562Asp), NHS (c.568G>C, p.Val190Leu-de novo variant), NOTCH2 (c.1997A>G, p.Tyr666Cys), TBX18 (c.647A>T, p.His225Leu), VAX1 (c.400G>A, p.Ala134Thr) and WNT5B (c.716G>T, p.Arg239Leu). The remaining risk variants were identified within genes previously linked to ns-CP, confirming their contribution to this anomaly. This list included ARHGAP29 (c.1706G>A, p.Arg569Gln), FLNB (c.3605A>G, Tyr1202Cys), IRF6 (224A>G, p.Asp75Gly-de novo variant), LRP6 (c.481C>A, p.Pro161Thr) and TP63 (c.353A>T, p.Asn118Ile). In summary, this study provides further insights into the genetic components contributing to ns-CP aetiology and identifies novel susceptibility genes for this craniofacial anomaly.

Treatment selection in multi-arm multi-stage designs: With application to a postpartum haemorrhage trial.

Multi-arm multi-stage trials are an efficient, adaptive approach for testing many treatments simultaneously within one protocol. In settings where numbers of patients available to be entered into trials and resources might be limited, such as primary postpartum haemorrhage, it may be necessary to select a pre-specified subset of arms at interim stages even if they are all showing some promise against the control arm. This will put a limit on the maximum number of patients required and reduce the associated costs. Motivated by the World Health Organization Refractory HaEmorrhage Devices trial in postpartum haemorrhage, we explored the properties of such a selection design in a randomised phase III setting and compared it with other alternatives. The objectives are: (1) to investigate how the timing of treatment selection affects the operating characteristics; (2) to explore the use of an information-rich (continuous) intermediate outcome to select the best-performing arm, out of four treatment arms, compared with using the primary (binary) outcome for selection at the interim stage; and (3) to identify factors that can affect the efficiency of the design. We conducted simulations based on the refractory haemorrhage devices multi-arm multi-stage selection trial to investigate the impact of the timing of treatment selection and applying an adaptive allocation ratio on the probability of correct selection, overall power and familywise type I error rate. Simulations were also conducted to explore how other design parameters will affect both the maximum sample size and trial timelines. The results indicate that the overall power of the trial is bounded by the probability of 'correct' selection at the selection stage. The results showed that good operating characteristics are achieved if the treatment selection is conducted at around 17% of information time. Our results also showed that although randomising more patients to research arms before selection will increase the probability of selecting correctly, this will not increase the overall efficiency of the (selection) design compared with the fixed allocation ratio of 1:1 to all arms throughout. Multi-arm multi-stage selection designs are efficient and flexible with desirable operating characteristics. We give guidance on many aspects of these designs including selecting the intermediate outcome measure, the timing of treatment selection, and choosing the operating characteristics.

УПОТРЕБЛЕНИЕ АЛКОГОЛЯ СРЕДИ СОВРЕМЕННЫХ ГОРОДСКИХ ПОДРОСТКОВ-ШКОЛЬНИКОВ

Significance. Alcohol use (alcoholization) is one of the most common health risks that starts to develop in adolescence. The purpose of the study is to identify characteristics of alcohol use among modern urban adolescent schoolchildren. Material and methods. Alcohol use among urban adolescent schoolchildren aged 15-17 years was studied as part of the monitoring of consumption of psychoactive substances (PSA): alcohol, tobacco, narcotic substances in 2019-2020. The sampling of adolescents was guided by the method of multi-stage selection: from typological and random to continuous anonymous questioning. The study covered 12 cities from 6 Federal Districts of the Russian Federation. 14084 teenagers were examined including 6535 (46.4%) boys and 7549 (53.6%) girls. Statistical data processing included calculation of absolute and relative indicators. To calculate the statistical significance of differences in indicators, the nonparametric Pearson test (χ2) was used. Results. On average, the prevalence of alcohol use in adolescents in the surveyed cities equaled to 37.0 per 100 adolescents of the corresponding sex and age (p<0.001) among boys and 49.0 - among girls. Adolescents who frequently drink alcohol (twice a month or more often) are a “risk group”, the share of this group equals to 6.7 in boys and 7.83 in girls per 100 adolescents (p<0.01). The main motives for alcohol use in adolescents are traditional events - holidays and family celebrations - 49.1% of boys and 53.8% of girls. The number of those who first try alcohol under 12 years has decreased with the peak in the debut shifting to 13-16 years. Awareness of adolescents about dangers of alcohol is insufficient. Only about 60% consider alcohol unhealthy. Conclusion. Alcohol use among modern adolescents is characterized by a lower prevalence and a postponed first introduction to alcohol.