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Family studies routinely employ biased sampling schemes in which individuals are randomly chosen from a disease registry and genetic and phenotypic data are obtained from their consenting relatives. We view this as a two-phase study and propose the use of an efficient selection model for the recruitment of families to form a phase II sample subject to budgetary constraints. Simple random sampling, balanced sampling and use of an approximately optimal selection model are considered where the latter is chosen to minimize the variance of parameters of interest. We consider the setting where family members provide current status data with respect to the disease and use copula models to address within-family dependence. The efficiency gains from the use of an optimal selection model over simple random sampling and balanced sampling schemes are investigated as is the robustness of optimal sampling to model misspecification. An application to a family study on psoriatic arthritis is given for illustration.

RESUMO Neste artigo implementou-se o modelo de satisfação ECSI (European Customer Satisfaction Index) em uma das principais empresas brasileiras fornecedoras de Enterprise Resource Planning (ERP). O ECSI analisa o relacionamento da satisfação com seus antecedentes (imagem, expectativa, qualidade e valor) e conseqüentes (reclamação e lealdade). Para esta pesquisa, o modelo original foi modificado, retirando-se o construto reclamação. A pesquisa contou com duas fases: na exploratória foram realizadas entrevistas em profundidade e grupo de foco. Na fase descritiva foi realizado um e-survey, com 684 casos válidos. As escalas foram adaptadas de outros estudos, exceto para o construto qualidade, em que uma nova escala foi proposta e validada. O tratamento estatístico foi apoiado por técnicas multivariadas, incluindo a Modelagem de Equações Estruturais. Constatou-se que existe uma relação positiva forte entre imagem, qualidade e satisfação na propensão dos clientes à lealdade. Os resultados da pesquisa são discutidos, bem como suas implicações para futuras pesquisas e para a prática gerencial. ABSTRACT This research implemented the ECSI model (European Customer Satisfaction Index), in one of the most important Brazilian organization, that supplies ERP systems. The ECSI analyses the relationship among satisfaction with its antecedents (image, expectative quality and value) and its outcomes (complaint and loyalty). The original model was modified, as the complaint construct was dropped from the model. The methodology was implemented using a two phase design. The exploratory phase was developed applying focus groups and in deep interviews. At the descriptive phase, an e-survey was accomplished, obtaining 684 valid cases. The scales were obtained from previous studies, except the quality scale, that was developed specifically for this study. The data was analyzed using structural equation modeling and multivariate techniques. It was observed that there is a strong positive impact on loyalty, which was provided by image, quality and satisfaction. Finally, the results are discussed, as the implications for managers and future research.

Plant breeders always face the challenge to select the best individuals. Selection methods are required that maximize selection gain based on available data. When several crosses have been made, the BLUP procedure achieves this by combining phenotypic data with information on pedigree relationships via an index, known as family-index selection. The index, estimated based on the intra-class correlation coefficient, exploits the relationship among individuals within a family relative to other families in the population. An intra-class correlation coefficient of one indicates that the individual performance can be fully explained based on the family background, whereas an intra-class correlation coefficient of zero indicates the performance of individuals is independent of the family background. In the case, the intra-class correlation coefficient is one, family-index selection is considered. In the case the intra-class correlation coefficient is zero, individual selection is considered. The main difference between individual and family-index selection lies in the adjustment in estimating the individual’s effect depending on the intra-class correlation coefficient afforded by the latter. Two examples serve to illustrate the application of the BLUP method. The efficiency of individual and family-index selection was evaluated in terms of the heritability obtained from linear mixed models implementing the selection methods by suitably defining the treatment factor as the sum of individual and family effect. Family-index selection was found to be at least as efficient as individual selection in Dianthus caryophyllus L., except for flower size in standard carnation and vase life in mini carnation for which traits family-index selection outperformed individual selection. Family-index selection was superior to individual selection in Pelargonium zonale in cases when the heritability was low. Hence, the pedigree-based BLUP procedure can enhance selection efficiency in production-related traits in P. zonale or shelf-life related in D. caryophyllus L.

Using a mixed-method two-phase design approach, this study explores the relative convenience, relative advantages, perceived privacy, and perceived security of WeChat Pay, as perceived by foreign users living in China and their intention to keep using this mobile wallet. This study also examines how Relative Convenience, Relative Advantage, Perceived Privacy, and Perceived Security of WeChat Pay influence Continuous Use Intention of this mobile wallet among foreign users. Results from a qualitative investigation (N = 70 responses) and quantitative investigation (N = 472) indicate that WeChat Pay is relatively more convenient and advantageous and also offers relatively more security and privacy protection compared to the traditional payment methods. The results also show that Relative Convenience, Relative Advantages, Perceived Privacy, and Perceived Security influence positively Continuous Use Intention of WeChat Pay among foreign users living in China. Based on these findings, theoretical and managerial contributions and the limitations of this study are discussed and also suggestions for future research are provided.

Background Burn patients often receive their initial care by non-burn specialist clinicians, with increasingly collaborative burn models of care. The provision of relevant and accessible education for these clinicians is therefore vital for optimal patient care. Design/methods A two phase design was used. A state-wide survey of multidisciplinary non-burn specialist clinicians throughout Western Australia identified learning needs related to paediatric burn care. A targeted education programme was developed and delivered live via videoconference. Pre-post-test analysis evaluated changes in knowledge as a result of attendance at each education session. Results Non-burn specialist clinicians identified numerous areas of burn care relevant to their practice. Statistically significant differences between perceived relevance of care and confidence in care provision were reported for aspects of acute burn care. Following attendance at the education sessions, statistically significant increases in knowledge were noted for most areas of acute burn care. Conclusions Identification of learning needs facilitated the development of a targeted education programme for non-burn specialist clinicians. Increased non-burn specialist clinician knowledge following attendance at most education sessions supports the use of videoconferencing as an acceptable and effective method of delivering burns education in Western Australia.

This is the peer reviewed version of the following article: McIsaac, M. A. and Cook, R. J. (2014), Response-dependent two-phase sampling designs for biomarker studies. Can J Statistics, 42: 268–284. doi: 10.1002/cjs.11207, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/cjs.11207/references. This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.

Purpose Claims databases are an important source for pharmacoepidemiological studies although they often lack information on some confounders. Two-phase methodology was used to estimate the bleeding risk in patients treated with phenprocoumon from claims data combined with additional information on body mass index (BMI) and smoking. Methods We conducted a nested case–control study using claims data from 2004 to 2007 (phase 1). Additional information was obtained from interviews in a subset of 505 insurants (phase 2). Adjusted bleeding OR were calculated using logistic regression using data from the complete case–control dataset. Furthermore, a two-phase analysis was conducted, taking into consideration phase 2 data on BMI and smoking. Results The phase 1 sample included 1248 cases and 24 960 controls. In phase 1, we observed an adjusted bleeding ORs of 3.93 (95%CI: 2.75–5.61) for male subjects aged 55 years taking phenprocoumon. The bleeding risk associated with phenprocoumon use decreased with increasing age. The two-phase analysis revealed smoking and a high BMI as risk factors for bleeding. The OR for phenprocoumon obtained from the two-phase analysis was of similar size as the phase 1 estimate. Discussion Phase 2 data added valuable information on smoking and BMI. However, phase 1 results did not change dramatically after accounting for phase 2 information, which is reassuring for the validity of database studies. Copyright © 2012 John Wiley & Sons, Ltd.

OBJECTIVE: The objective of the trial was to determine the efficacy of the proven anticalculus active system (zinc citrate trihydrate [ZCT] and triclosan), when the ZCT is delivered from microgranules incorporated in a silica-based toothpaste containing 1450 ppm F as sodium fluoride. DESIGN: A monadic, single-blind, two phase design clinical trial was used to compare the effect of the test and a negative control fluoridated toothpaste on the formation of supragingival calculus. SUBJECTS AND METHODS: Male and female calculus-forming volunteers, aged 18 or over, were recruited for the study following a 2-week screening phase. All subjects were given a scale and polish of their eight lower anterior teeth at the start of both the pre-test and test phases. Subjects were supplied with a silica-based 1450 F ppm fluoridated toothpaste with no anti-calculus active for use during an 8-week pre-test phase. Calculus was assessed at the end of the pre-test and test phases using the Volpe-Manhold index (VMI). Subjects were stratified according to their pre-test VMI score (8–10, 10.5–12, > 12) and gender and then allocated at random to test or negative control toothpaste groups. Subjects with < 8 mm of calculus were excluded from further participation. MAIN OUTCOME MEASURE: The outcome variable was the mean VMI score for the test and negative control groups. RESULTS: The test toothpaste caused a statistically significant 30% reduction in calculus compared with the control paste after a 13-week use. No adverse events were reported during the study. CONCLUSION: The incorporation of the ZCT in microgranules did not adversely affect the anticalculus activity of the new formulation.

This study demonstrates how explicit metacognitive training influences the mathematical word-problem solving of forty 11-12-year-old low achievers in a cognitive-apprenticeship, computer-based environment. Results from the experimental and case study designs revealed that experimental students outperformed control students on ability to solve word-problems on their individual written measures; experimental students developed the ability to ascertain when to make metacognitive decisions, and elicit better regulated metacognitive decisions than control students; knowing when and how to use metacognitive strategies is an important determinant to successful word-problem solving; and the cognitive-apprenticeship-computer-based environment appears to amplify low achievers' metacognitive and cognitive behaviours during word-problem solving.

Community-based rehabilitation can help to maximize function following acquired brain injury (ABI); however, data on treatment outcome is limited in quantity.To describe and evaluate client outcomes of an outpatient programme for adults with moderate-to-severe traumatic and non-traumatic ABI.Two phase design involving retrospective and longitudinal study of programme completers with ABI (n = 47). Changes in functioning were measured with the Mayo-Portland Inventory (MPAI-4), administered pre- and immediately post-rehabilitation and at 3 years follow-up. Self-ratings were supplemented with MPAI-4 data from significant others (n = 32) and staff (n = 32).Injured individuals and informants reported improved physical and psychosocial functioning immediately following the completion of community rehabilitation, with medium-to-large and significant treatment gains noted on the MPAI-4 ability, adjustment and participation sub-scales (Cohen's d range = 0.31-1.10). A deterioration in individuals' adjustment was further reported at follow-up, although this was based on limited data. Issues with longer-term rehabilitation service provision were additionally noted.The data support the need for continuity of care, including ongoing emotional support, to cater to the complex and dynamic needs of the ABI population. However, these results need to be considered in the context of a small sample size and quasi-experimental design.

In this paper, we present a two-phase design space exploration (DSE) approach to address the problem of real-time application mapping on a flexible MPSoC platform. Our approach is composed of two independent phases - analytical estimation/pruning and system simulation - communicating via a well-defined interface. The strength of the resulting strategy is twofold. On one hand, it is capable of combining the benefits of analytical models and simulation tools (i.e., speed and accuracy). And on the other hand, separating pruning and evaluation phases facilitates the integration of different or additional pruning techniques as well as other existing simulation tools. Finally, we also present several proof-of-concept DSE experiments to illustrate distinct aspects and capabilities of our framework. These experimental results reveal that our approach, compared to other approaches based only on analytical estimation models or simulations guided by e.g. genetic algorithms, not only can explore a large design space and reach a valid solution in a time-efficient way, but also can provide solutions optimizing resource usage efficiency, system traffic and processor load balancing.

An epidemiological study often uses a two-phase design to estimate the prevalence rate of a mental disease. In a two-phase design study, the first phase assesses a large sample with an inexpensive screening test, and then the second phase selects a subsample for a more expensive diagnostic evaluation. Furthermore, disease status may not be ascertained for all subjects who are selected for disease verification because some subjects are unable to be clinically assessed, while others may refuse. Since not all screened subjects are selected for diagnostic assessments, there is potential for verification bias. In this paper, we propose the maximum likelihood (ML) and bootstrap methods to correct for verification bias for estimating and comparing the prevalence rates under the missing-at-random (MAR) assumption for the verification mechanism. We also propose a method to test this MAR assumption. Finally, we apply our methods to a large-scale prevalence study of dementia disorders.

In pharmaceutical analysis, the window that cases effective response with probability larger than p is important and need to be precisely estimated. For this difficult issue, we propose a two-phase design by combining D-optimal strategy and likelihood recursive approximation to estimate it. Simulation study shows that the estimate is accurate and reliability.

Similar in size (62 kg, 1.8 m long) and shape to the Seaglider [1], the Deepglider is an instrument platform designed to glide to depths of 6000 meters. To achieve these depths, a composite pressure hull of thermoset resin and carbon fiber was developed in a two phase design and test approach. To take advantage of the substantial engineering effort put into the Seaglider, the Deepglider was designed to use many of the same components and technologies. A Deepglider was deployed in November 2006 off the Washington state coast. It remained at sea for 39 days, diving to a maximum water depth of 2713 meters, and transiting to its target 220 km offshore, before returning and being recovered near shore. The Deepglider, while not yet achieving its design goal of 6000 meters, demonstrated that composites can provide a strength-to-weight ratio exceeding that of metals and can be optimized for hydrodynamic body shapes. This paper describes the Deepglider development and the issues of compressibility for a profiling glider.

In a two phase design, an attempt was made to differentiate the effect of marijuana on the storage and retrieval of prose material. In the first phase, 40 male subjects were administered a single 500 mg marijuana cigarette containing 2.1%delta9-THC or a placebo cigarette. Fifteen minutes after smoking, they listened to and at the same time read a narrative passage of approximately 200 words in length. Subsequently, an immediate free recall test was given in which subjects were required to write down as much of the story as they could remember. The second phase was conducted 24h later. Marijuana and placebo subjects were randomly subdivided into four groups with half of the subjects participating in the same drug condition as occurred on day one while the others switched drug state. Fifteen minutes after smoking, all subjects recalled the passage presented on day one and then were given 24 questions concerning facts and events in the story which could be answered in a few words. These questions served as retrieval cues. Following this, a new passage was presented in the same manner as occurred on day one. After an immediate free recall test, another cued recall test was administered. Results indicated that marijuana reduced immediate recall under both cued and uncued conditions incomparison to placebo. No relative cued recall advantage was found in the marijuana groups for the old or new story and marijuana produced only a moderate decrement in recall of the old story on day two. However, marijuana given in the second phase significantly reduced memory for items recalled in the initial phase irrespective of drug or cueing condition in phase one, suggesting that retrieval was also affected. Some decrement in recall of the new story did occur as a function of drug state change in group M-P. This effect was related to the serial position of input items. Serial position did not interact with drug state under any other recall condition.

Background In resource-limited settings, monitoring and evaluation (M&E) of antiretroviral treatment (ART) programs often relies on aggregated facility-level data. Such data are limited, however, because of the potential for ecological bias, although collecting detailed patient-level data is often prohibitively expensive. To resolve this dilemma, we propose the use of the two-phase design. Specifically, when the outcome of interest is binary, the two-phase design provides a framework within which researchers can resolve ecological bias through the collection of patient-level data on a sub-sample of individuals while making use of the routinely collected aggregated data to obtain potentially substantial efficiency gains. Methods Between 2005–2007, the Malawian Ministry of Health conducted a one-time cross-sectional survey of 82,887 patients registered at 189 ART clinics. Using these patient data, an aggregated dataset is constructed to mimic the type of data that it routinely available. A hypothetical study of risk factors for patient outcomes at 6 months post-registration is considered. Analyses are conducted based on: (i) complete patient-level data; (ii) aggregated data; (iii) a hypothetical case–control study; (iv) a hypothetical two-phase study stratified on clinic type; and, (v) a hypothetical two-phase study stratified on clinic type and registration year. A simulation study is conducted to compare statistical power to detect an interaction between clinic type and year of registration across the designs. Results Analyses and conclusions based solely on aggregated data may suffer from ecological bias. Collecting and analyzing patient data using either a case–control or two-phase design resolves ecological bias to provide valid conclusions. To detect the interaction between clinic type and year of registration, the case–control design would require a prohibitively large sample size. In contrast, a two-phase design that stratifies on clinic and year of registration achieves greater than 85% power with as few as 1,000 patient samples. Conclusions Two-phase designs have the potential to augment current M&E efforts in resource-limited settings by providing a framework for the collection and analysis of patient data. The design is cost-efficient in the sense that it often requires far fewer patients to be sampled when compared to standard designs.