Balanced Incomplete Block Research Articles

Caregiver priorities for endpoints to evaluate treatments for Prader-Willi syndrome: a best–worst scaling

Objectives: Prader-Willi syndrome (PWS) is a rare genetic disorder associated with varying degrees of hyperphagia, obesity, intellectual disability, and anxiety across the affected individuals’ lifetimes. This study quantified caregiver priorities for potential treatment endpoints to identify unmet needs in PWS.Methods: The authors partnered with the International Consortium to Advance Clinical Trials for PWS (PWS-CTC) and a diverse stakeholder advisory board to develop a best–worst scaling instrument. Seven relevant endpoints were assessed using a balanced incomplete block design. Caregivers were asked to determine the most and least important of a sub-set of four endpoints in each task. Caregivers were recruited nationally though patient registries, email lists, and social media. Best–worst score was calculated to determine caregiver priorities; ranging from 0 (least important) to 10 (most important). A novel kernel-smoothing approach was used to analyze caregiver endpoint priority variations with relation to age of the PWS individual.Results: In total, 457 caregivers participated in the study. Respondents were mostly parents (97%), females (83%), and Caucasian (87%) who cared for a PWS individual ranging from 4–54 years. Caregivers value treatments addressing hyperphagia (score = 7.08, SE = 0.17) and anxiety (score = 6.35, SE = 0.16) as most important. Key variations in priorities were observed across age, including treatments targeting anxiety, temper outbursts, and intellectual functions.Conclusions: This study demonstrates that caregivers prioritize hyperphagia and, using a novel method, demonstrates that this is independent of the age of the person with PWS. This is even the case for parents of young children who have yet to experience hyperphagia, indicating that these results are not subject to a hypothetical bias.

Dose-response between frequency of interruption of sedentary time and fasting glucose, the dawn phenomenon and night-time glucose in Type 2 diabetes.

To explore the dose-response between frequency of interruption of sedentary time and basal glucose (fasting glucose, the dawn phenomenon and night-time glucose) in Type 2 diabetes. In a randomized three-treatment, two-period balanced incomplete block trial, 12 people with Type 2 diabetes (age, 60.0±3.2 years; BMI, 30.2±1.4 kg/m2 ) completed two of three conditions: sitting for 7h interrupted every 60min (Condition 1), 30min (Condition 2), and 15min (Condition 3) by 3-min light-intensity walking breaks. The activPAL3 and FreeStyle Libre were used to assess physical activity/sedentary behaviour and continuous glucose profile. Standardized meals were provided, and changes in basal glucose of the nights and early mornings before and after treatment conditions were calculated (mean±SE). After treatment conditions, fasting glucose and duration of the dawn phenomenon were lower for Condition 3 (-1.0±0.2 mmol/l, P<0.02; -3.1±1.3h, P=0.004) compared with Condition 1 (-0.1±0.2 mmol/l; 1.9±1.2h). The magnitude of the dawn phenomenon was reduced in Condition 3 (-0.6±0.4 mmol/l, P=0.041) compared with Condition 2 (0.6±0.3 mmol/l). Night-time glycaemic variability (coefficient of variation) was reduced in Condition 3 (-9.7±3.9%) relative to Condition 2 (6.1±4.8%, P < 0.03) and Condition 1 (2.5±1.8%, P = 0.02). There was no change in night-time mean glucose. Frequent interruptions of prolonged sitting with 3min of light-intensity walking breaks every 15min improves fasting glucose, the dawn phenomenon and night-time glycaemic variability, and this might be a simple therapeutic intervention to improve glucose control. Clinicaltrials.gov Identifier: NCT02738996.

PDB127 - APPLICATION OF BEST WORST SCALING TO IMPROVE PATIENT-CENTERED TREATMENT DECISIONS IN DIABETIC PERIPHERAL NEUROPATHY

Treatment of diabetic peripheral neuropathy (DPN) symptoms is challenging due to variable treatment effectiveness and side effects. This study evaluated best-worst scaling as a strategy for patient-centered tailoring of treatment choice. We designed an object case best-worst scaling preference instrument to identify DPN treatment attributes of least and most importance to patients. An initial set of 9 attributes was identified through coding and analysis of transcripts from in-depth interviews with 42 patients with DPN symptoms in a large U.S. health system. We used Sawtooth Software to design a balanced incomplete block design of the survey instrument. We then conducted 2 rounds of iterative pilot testing with interviewers and patients (n=19), resulting in a refined instrument with 7 attributes with 2 levels each. The final survey instrument was limited to 4 choices per set and a total of 15 sets per patient. We fielded the survey among a random sample of 100 patients who were actively being treated for DPN symptoms. The importance score was then calculated for each patient. Preference assessments were conducted with 100 patients with an average age of 61. Most of the participants were female (52%) and were 34% White, 33% Black, 16% Asian, 14% Hispanic and 3% unknown race or ethnicity. The attribute identified by patients as being most important to decision-making was functioning “I can do the things that I usually do”. The second most important attribute was whether “my doctor and I discuss my concerns about this medication”. The attributes identified as least important were medication cost and whether they had to take more than one pill every day. This study provides real-world evidence regarding the treatment preferences of adults with DPN symptoms. Healthcare innovations in DPN are needed to foster patient-provider communication about treatment preferences, particularly related to functioning.

Design and evaluation of ranking-type Delphi studies using best-worst-scaling

ABSTRACTThe ranking-type Delphi method has received widespread use in a large number of research areas. In order to rank a set of items, ranking-type Delphi studies use different ranking approaches which may be biased. This is intensified by the fact that the number of issues a participant can reasonably rank is limited. This paper describes an approach for the design and evaluation of ranking-type Delphi studies using best-worst-scaling (BWS). The statistical BWS design is based on a balanced incomplete block design to construct the comparison sets. The statistical evaluation encompasses the measurement of stability and consensus with the use of the coefficient of variation. Overall, our approach (1) enables to design a ranking with up to 22 items in a manner that participants can reasonably rank, (2) avoids and overcomes shortcomings of common ranking approaches, and (3) offers a statistical procedure for an unambiguous evaluation.

Development of Java Tea based Functional Drink: Scale-up FormulaOptimization based on the Sensory and Antioxidant Properties

In supporting of product industrialization, development of Java Tea based functional drink was modified by using simplicia extracts produced by selected toll manufacturing. However, modification will impact product’s efficacy as well as the sensory properties. This study aimed to optimize the formula of Java Tea based functional drink based on the sensory and antioxidant properties made from simplicia extracts. Formula optimization was determined by response surface methodology (RSM) using Design Expert® 7 program. Java tea extract (JE), sappan wood extract (SE), ginger extract (GE) and lime extract (LE) were determined as factors due to their potential of antioxidant and sensory properties. Sensory evaluation was deployed by using balanced incomplete block design (BIBD) method. A Java Tea based functional drink made from simplicia extracts with optimum sensory and antioxidant properties has been successfully formulated. The verified model showed that antioxidant activity of the optimum formula was 335.69 ± 48.30 ppm ascorbic acid equivalent antioxidant capacity and the sensory acceptances (7 scales) for colour, taste, aroma and overall attributes were 5.6, 5.8, 5.2 and 5.2 (like moderately to like slightly), respectively. Utilization of simplicia’s extract showed a potential conformity with the fresh ingredients in the development of Java Tea based functional drink.

Group Divisible Variance – Sum Third Order Rotatable Design through Balanced Incomplete Block Designs in Four Dimensions

&#x0D; &#x0D; &#x0D; &#x0D; In the study of rotatable designs, the variance of the estimated response at a point is a function of the distance of that point from a particular origin. Group divisible Rotatable Designs have been evolved by imposing conditions on the levels of factors in a rotatable design. In Group Divisible Third Order Rotatable Designs (GDTORD), the v-factors are split into two groups of p and (v-p) factors such that the variance of a response estimated at a point equidistant from the centre of the designs is a function of the distances and from a suitable origin for each group respectively. Where and denotes the distances of the projection of the points in each of the group from a suitable origin respectively. In this paper, a four dimensional Group Divisible Variance-Sum Third Order Rotatable Design is constructed using a balanced incomplete block design.&#x0D; &#x0D; &#x0D; &#x0D; &#x0D;

Near-Balanced Incomplete Block Designs, With an Application to Poster Competitions

ABSTRACTJudging scholarly posters creates a challenge to assign the judges efficiently. If there are many posters and few reviews per judge, the commonly used balanced incomplete block design is not a feasible option. An additional challenge is an unknown number of judges before the event. We propose two connected near-balanced incomplete block designs that both satisfy the requirements of our setting: one that generates a connected assignment and balances the treatments and another one that further balances pairs of treatments. We describe both fixed and random effects models to estimate the population marginal means of the poster scores and rationalize the use of the random effects model. We evaluate the estimation accuracy and efficiency, especially the winning chance of the truly best posters, of the two designs in comparison with a random assignment via simulation studies. The two proposed designs both demonstrate accuracy and efficiency gain over the random assignment.

A cluster-randomised evaluation of an adaptable implementation strategy targeting ‘high impact’ indicators in primary care

BackgroundRecognised gaps between evidence and practice in primary care present particular implementation challenges when addressing multiple priorities.AimTo evaluate the effectiveness of a multifaceted, adaptable implementation package targeting four different ‘high impact’ indicators.MethodWe undertook two parallel, pragmatic cluster randomised trials using balanced incomplete block designs with parallel process evaluation. General practices in West Yorkshire, UK, were recruited using an ‘opt out’ process. The adaptable implementation package included audit and feedback, educational outreach visits and computerised support with embedded behaviour change techniques tailored to each indicator. Practices were randomised to packages targeting either type 2 diabetes control or risky prescribing of non-steroidal anti-inflammatory drugs, or packages targeting either anticoagulation in atrial fibrillation or blood pressure control in patients at high risk of cardiovascular events. Respective primary endpoints comprised: achievement of all recommended levels of haemoglobin A1c, blood pressure and cholesterol; risky prescribing levels; anticoagulation prescribing; and achievement of recommended blood pressure levels. Outcomes at 11 months used routinely collected data.Results178 out of 244 eligible practices participated. The implementation package reduced risky prescribing (odds ratio 0.82; 97.5% confidence interval 0.67 to 0.99). There was no effect on other primary endpoints.ConclusionThis highly pragmatic, robust evaluation suggests the value of targeting risky prescribing, given predictable population reductions in avoidable morbidity, deaths and hospital admissions. However, in broad terms, an adapted ‘one-size-fits-all’ approach did not consistently work, with no improvement for other targeted indicators.

The Application of Algebraic Methods in Balanced Incomplete Block Design

A balanced incomplete block design contains finite set P with v elements called varieties and a collection of set B consisting of b sets called blocks to qualify: (i). each block contains k varieties, (ii). Each variety occurs in every r blocks, (iii). Each pair of varieties occurs in exactly λ block. In this paper we discuss the use of algebraic method to construct such designs.

PSY68 - Identifying Caregiver Priorities for Treatment Endpoints for Prader-Willi Syndrome with Best-Worst Scaling

Prader-willi syndrome (PWS) is a rare genetic disorder associated with varying degrees of hyperphagia, obesity, intellectual disability, and anxiety across the affected individuals’ lifetime. We quantified caregiver priorities for possible treatment endpoints to identify unmet needs across the natural history of the disease. We partnered with the PWS Clinical Trials Consortium and a diverse stakeholder advisory board to develop a best-worst scaling instrument to assess seven relevant endpoints. A balanced incomplete block design was used to develop seven choice tasks where caregivers were asked to determine the most and least important of a subset of four treatment benefits listed in each task. Caregivers were recruited nationally though patient registry, email lists, blogs and Facebook. Best-worst score was calculated to determine caregiver priorities; with a range between -1 and 1, 1 being most important. A novel kernel-smoothing approach was used to analyze across age. Of the 457 participants, caregivers were predominately parents (97%), female (83%) and Caucasian (87%) who cared for a patient with PWS ranging from 4-54 years (mean=15.6). The respondents value treatments addressing hyperphagia (score=0.417, SE: 0.01) and anxiety (score = 0.217, SE: 0.01) as most important. Key variations in priorities were observed across age, including reducing anxiety, decreasing temper outbursts, and improving intellectual functions. We demonstrated variation in prioritized endpoints throughout the natural disease history of a broad-spectrum disease. The study provides a model to engage diverse stakeholders to assess unmet needs and determine treatment priorities. The study is limited in that we used caregivers’ as surrogates and the patients’ perspectives have not been fully explored.

On the Classification of Splitting (v, u×c, λ) BIBDs

Abstract The (v, u×c, λ)-splitting balanced incomplete block designs correspond to c-splitting authentication codes. We classify splitting balanced incomplete block designs with definite parameters.

Anonymous and Traceable Group Data Sharing in Cloud Computing

Group data sharing in cloud environments has become a hot topic in recent decades. With the popularity of cloud computing, how to achieve secure and efficient data sharing in cloud environments is an urgent problem to be solved. In addition, how to achieve both anonymity and traceability is also a challenge in the cloud for data sharing. This paper focuses on enabling data sharing and storage for the same group in the cloud with high security and efficiency in an anonymous manner. By leveraging the key agreement and the group signature, a novel traceable group data sharing scheme is proposed to support anonymous multiple users in public clouds. On the one hand, group members can communicate anonymously with respect to the group signature, and the real identities of members can be traced if necessary. On the other hand, a common conference key is derived based on the key agreement to enable group members to share and store their data securely. Note that a symmetric balanced incomplete block design is utilized for key generation, which substantially reduces the burden on members to derive a common conference key. Both theoretical and experimental analyses demonstrate that the proposed scheme is secure and efficient for group data sharing in cloud computing.

A Hierarchical RAID Architecture Towards Fast Recovery and High Reliability

Disk failures are very common in modern storage systems due to the large number of inexpensive disks. As a result, it takes a long time to recover a failed disk due to its large capacity and limited I/O. To speed up the recovery process and maintain a high system reliability, we propose a hierarchical code architecture with erasure codes, OI-RAID, which consists of two layers of codes, outer layer code and inner layer code. Specifically, the outer layer code is deployed with disk grouping technique based on Balanced Incomplete Block Design (BIBD) or complete graph with skewed data layout to provide efficient parallel I/O of all disks for fast failure recovery, and the inner layer code is deployed within each group of disks to provide high reliability. As an example, we deploy RAID5 in both layers to achieve fault tolerance of at least three disk failures, which meets the requirement of data availability in practical systems, as well as much higher speed up ratio for disk failure recovery than existing approaches. Besides, OI-RAID also keeps the optimal data update complexity and incurs low storage overhead in practice.

Frame difference families and resolvable balanced incomplete block designs

Frame difference families, which can be obtained via a careful use of cyclotomic conditions attached to strong difference families, play an important role in direct constructions for resolvable balanced incomplete block designs. We establish asymptotic existences for several classes of frame difference families. As corollaries new infinite families of 1-rotational $$(pq+1,p+1,1)$$ -RBIBDs over $${\mathbb {F}}_{p}^+ \times {\mathbb {F}}_{q}^+$$ are derived, and the existence of $$(125q+1,6,1)$$ -RBIBDs is discussed. We construct (v, 8, 1)-RBIBDs for $$v\in \{624,$$ $$1576,2976,5720,5776,10200,14176,24480\}$$ , whose existence were previously in doubt. As applications, we establish asymptotic existences for an infinite family of optimal constant composition codes and an infinite family of strictly optimal frequency hopping sequences.

A note on the robustness of PBIBD(2)s against breakdown in the event of observation loss

SummaryRobustness against design breakdown following observation loss is investigated for Partially Balanced Incomplete Block Designs with two associate classes (PBIBD(2)s). New results are obtained which add to the body of knowledge on PBIBD(2)s. In particular, using an approach based on the E‐value of a design, all PBIBD(2)s with triangular and Latin square association schemes are established as having optimal block breakdown number. Furthermore, for group divisible designs not covered by existing results in the literature, a sufficient condition for optimal block breakdown number establishes that all members of some design sub‐classes have this property.

Maximal orthoplectic fusion frames from mutually unbiased bases and block designs

The construction of optimal line packings in real or complex Euclidean spaces has shown to be a tantalizingly difficult task, because it includes the problem of finding maximal sets of equiangular lines. In the regime where equiangular lines are not possible, some optimal packings are known, for example, those achieving the orthoplex bound related to maximal sets of mutually unbiased bases. In this paper, we investigate the packing of subspaces instead of lines and determine the implications of maximality in this context. We leverage the existence of real or complex maximal mutually unbiased bases with a combinatorial design strategy in order to find optimal subspace packings that achieve the orthoplex bound. We also show that maximal sets of mutually unbiased bases convert between coordinate projections associated with certain balanced incomplete block designs and Grassmannian 2-designs. Examples of maximal orthoplectic fusion frames already appeared in the works by Shor, Sloane and by Zauner. They are realized in dimensions that are a power of four in the real case or a power of two in the complex case.

Using best-worst scaling choice experiments to elicit the most important domains of health for health-related quality of life in Singapore.

Health-related quality of life (HRQOL) instruments are sometimes used without explicit understanding of which HRQOL domains are important to a given population. In this study, we sought to elicit an importance hierarchy among 27 HRQOL domains (derived from the general population) via a best-worst scaling survey of the population in Singapore, and to determine whether these domains were consistently valued across gender, age, ethnicity, and presence of chronic illnesses. We conducted a community-based study that sampled participants with quotas for gender, ethnicity, age, presence of chronic illness, and interview language. For the best-worst scaling exercise, we constructed comparison sets according to a balanced incomplete block design resulting in 13 sets of questions, each with nine choice tasks. Each task involved three HRQOL domains from which participants identified the most and least important domain. We performed a standard analysis of best-worst object scaling design (Case 1) using simple summary statistics; 603 residents participated in the survey. The three most important domains of health were: “the ability to take care of self without help from others” (best-worst score (BWS): 636), “healing and resistance to illness” (BWS: 461), and “having good relationships with family, friends, and others” (BWS: 373). The 10 top-ranked domains included physical, mental, and social health. The three least important domains were: “having a satisfying sex life” (BWS: -803), “having normal physical appearance” (BWS: -461), and “interacting with others (talking, shared activities, etc.)” (BWS: -444). Generally, top-ranked domains were consistently valued across gender, age, ethnicity, and presence of chronic illness. We conclude that the 10 top-ranked domains reflect physical, mental, and social dimensions of well-being suggesting that the sampled population’s views on health are consistent with the World Health Organization’s definition of health, “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity”.

Best-Worst Scaling to Prioritize Outcomes Meaningful to Caregivers of Youth with Mental Health Multimorbidities: A Pilot Study.

Health care decision-making for youth with mental health multimorbidity is guided by outcomes that are considered most meaningful and important. The study objective was to pilot test a best-worst scaling (BWS) instrument designed to assess trade-offs among caregiver-defined, meaningful health care outcomes. A BWS was designed with continuous stakeholder involvement to elicit caregiver-defined outcomes in 4 domains: school, behavioral, social, and independence. Four attributes were identified for each outcome domain, for a total of 16 attributes. Using a balanced incomplete block design, a BWS instrument was developed with 16 choice task questions displaying 6 attributes at a time. A convenience sample was selected from Maryland caregivers of children who were 21 years old or younger and had a developmental delay and a comorbid mental health condition. Participants completed a survey that included demographics and the BWS instrument. Conditional logit was used to estimate utility scores and 95% confidence intervals (CI) for each attribute, which were ranked in order of importance. Attribute statements were refined after a respondent debriefing session. A total of 38 caregivers participated in the pilot study. Child safety to self was the most important outcome (1.01, CI, 0.78-1.24). This was followed by securing support for an Individualized educational plan in school (0.77, CI, 0.54-1.01) and the child being able to stay in school all day (0.53, CI, 0.29-0.77). BWS scenarios that resemble real-life decision-making can be a useful tool to identify preferences for health care outcomes.

Some sequences of optimal constant weight codes

We introduce some sequences of binary constant weight codes which are constructed from the affine constructions of balanced incomplete block designs. They give the values for the function [Formula: see text] of constant weight codes, and they are optimal since those values reach the Johnson Bound. We focus on the values obtained by this method.

Highly D‑efficient Weighing Design and Its Construction

In this paper, some aspects of design optimality on the basis of spring balance weighing designs are considered. The properties of D‑optimal and D‑efficiency designs are studied. The necessary and sufficient conditions determining the mentioned designs and some new construction methods are introduced. The methods of determining designs that have the required properties are based on a set of incidence matrices of balanced incomplete block designs and group divisible designs.