Two-phase Design Research Articles

Application of Multiple Imputation to Data from Two-phase Sampling: Estimation of the Incidence Rate of Cognitive Impairment

Epidemiological cohort study that adopts a two-phase design raises serious issue on how to treat a fairly large amount of missing val ues that are either Missing At Random (MAR) due to the study design or potentially Missing Not At Random (MNAR) due to non-response and loss to follow-up. Cognitive impairment (CI) is an evolving concept that needs epidemiological characterization for its maturity. In this work, we attempt to estimate the incidence rate CI by accounting for the aforemen tioned missing-data process. We consider baseline and first follow-up data of 2191 African-Americans enrolled in a prospective epidemiological study of dementia that adopted a two-phase sampling design. We developed a multiple imputation procedure in the mixture model framework that can be easily implemented in SAS. Sensitivity analysis is carried out to assess the dependence of the estimates on specific model assumptions. It is shown that African-Americans in the age of 65-75 have much higher incidence rate of CI than younger or older elderly. In conclusion, multiple imputation pro vides a practical and general framework for the estimation of epidemiological characteristics in two-phase sampling studies.

A new design method for two-phase nozzles in high efficiency heat pumps

In this paper an industrially established 1D model for two-phase nozzles design and analysis (Elliott, 1968) has been extended and validated with a wider range of experimental data, focusing on single component two-phase fluid expansion from initial quality in the 0%–25% range. The Authors focused on the correlations of the gas-liquid slip velocity and wall friction for two-flow regimes. The upgraded model has been tested on a converging nozzle showing accurate results under subcritical conditions (Ma<1). Furthermore, simulations have also been carried out on a convergent-divergent nozzle, concentrating on the diverging part at Ma>1, demonstrating that the new model obtained a significant reduction in error compared to the original Elliott model and to the well-known isentropic homogeneous approach (IHE). The extended model was also tested on a convergent-divergent nozzle produced by Carrier Corporation for the 19-XRT chiller, obtaining a satisfactory performance prediction. The validation process allowed to assess the limits of validity of the new model, which can be effectively used as design tool for subsonic or supersonic two-phase nozzles. In particular, the model capability to identify critical mass flow and critical expansion ratio has been investigated, showing good match for the critical expansion ratio, while margins of improvement remain for the critical mass flow prediction.

Pre-Service Teachers’ Perceptions of Emotions and Self-Regulatory Learning in Emergency Remote Learning

This study explored emotions and self-regulatory learning in postgraduate students, forced to transition to emergency remote teaching, at a Hong Kong university after the start of the academic semester. Self-regulation is a critical factor for successful online learning, and emotions are important antecedents of self-regulated learning. The study adopted a two-phase research design, with an initial online questionnaire (n = 52) followed by semi-structured interviews (n = 16) to gain a rich and holistic understanding of students’ experiences. Our findings indicate that: (1) locating a suitable location to attend online classes and sharing problems with classmates were the two most frequently self-regulatory learning strategies employed by students; (2) students experienced some enjoyment attending online classes but experienced increased pressure and time commitment to complete assigned work; (3) students found online learning to lack a sense of community, making it challenging to interact with classmates. The findings suggest teachers need to incorporate various synchronous and asynchronous collaborative activities, and they need to increase their own and students’ presence online to motivate and facilitate effective teaching and learning.

Vascular access and clinical competency: Which elements matter? The development of three bottom-up and evidence-grounded self-assessment tools.

Assessing competency in the speciality of vascular access is still limited, and few valid and reliable tools are available. Therefore, this study aimed to develop and validate three different tools for assessing competency in managing the care of short peripheral cannulas (SPCs), midlines, peripherally inserted central catheters (PICCs), centrally inserted central catheters (CICCs), and arterial catheters (ACs) (tool one), placing SPCs (tool two), placing PICCs and midlines (tool three). A two-phase and multi-method design was adopted. Phase one was implemented to develop the initial pool of items for each tool, starting from a literature overview. Panel discussions were adopted for developing the items. In phase two, the developed items were tested for content and face validity, involving a panel of 10 experts. Once obtained adequate content validity, a cross-sectional data collection was implemented to enroll three samples of healthcare workers who had to assess their competency through the developed tools. Dimensionality was assessed by performing a principal component analysis (PCA) and assessing internal consistency (Cronbach's α). Tool one had 26 items, and the dimensionality was given by placement, risk assessment, procedure conformity and traceability, and patient education to self-care. Tool two had 35 items; its principal components were: risk evaluation, identification, clinical assessment and orientation to self-care, placement, and procedure registration shaped the competency of placing SPCs. Tool three had 31 items; its principal components were: risk assessment, placement, conformity to standards and procedure traceability, education, and orientation to self-care were the essential elements for adequately placing midlines and PICCs. Cronbach's α values ranged between 0.806 and 0.959. The three developed tools reflected the core elements of competency in each application area, representing an initial framework that could be useful in future research and educational projects. Cross-national investigations are required to corroborate the described results.

Development of a professional practice competency for undergraduate nursing students: A mixed-method study

Nursing professionalism relates to the knowledge, skills, conduct, behaviour and attitudes of registered nurses. Difficulties related to student assessment of professionalism have been anecdotally described as a disparity between the meaning of the term ‘professionalism’ to nurses and its application and measurement in clinical practice. The aim of this study was to develop a professional practice competency for undergraduate nurses on clinical placement. An exploratory sequential mixed-methods approach with a two-phase design was used to develop the competency. Phase one, the Delphi method with 16 expert nurses, was used to develop the competency. This involved the thematic analysis of key statements over four rounds, five key themes were identified (attitudes, communication, knowledge, standards, relationships) that formed the framework and 33 individual competency statements. This was followed by phase 2, content validity, using the Table of Specification with 58 clinical facilitators. The findings confirmed the statements (80% consensus) deemed important to assess the essential construct of nursing professional practice. It is envisaged that the professional practice competency will assist student insight into their professional role and subsequently allow adjustment and achievement of professional practice competency.

Estimating the hazard rate difference from case-cohort studies.

The case-cohort design, among many two-phase sampling designs, substantially reduces the cost of an epidemiological study by selecting more informative participants within the full cohort for expensive variable measurements. Despite their benefits, additive hazards models, which estimate hazard differences, have rarely been used for the analysis of case-cohort studies due to the lack of software and application examples. In this paper, we describe a newly developed estimation method that fits the additive hazards models to general two-phase sampling studies along with the R package addhazard that implements it. It allows for missing covariates among cases, cohort stratification, robust variances, and the incorporation of auxiliary information from the full cohort to enhance inference precision. We demonstrate the use of this tool to estimate the association of the risk of coronary heart disease (CHD) with biomarkers high-sensitivity C-reactive protein (hs-CRP) and Lipoprotein-associated phospholipaseA2 (Lp-PLA2) by analyzing the Atherosclerosis Risk in Communities Study, which adopted a two-phase sampling design for studying these two biomarkers. We show that the use of auxiliary variables from the full cohort based on calibration techniques improves the precision of the hazard difference being estimated. We observe a synergistic effect of the two biomarkers among participants with lower LDL cholesterol (LDL-C): the CHD hazard rate attributable to the combined action of high hs-CRP and high Lp-PLA2 exceeded the sum of the CHD hazard rate attributable to each one independently by 11.58 (95% CI 2.16-21.01) cases per 1000 person-years. With higher LDL-C, we observe the CHD hazard rate attributable to the combined action of high hs-CRP and medium Lp-PLA2 was less than the sum of their individual effects by 13.42 (95% CI 2.44-24.40) cases per 1000 person-years. This demonstration serves the dual purposes of illustrating analysis techniques and providing insights about the utility of hs-CRP and Lp-PLA2 for identifying the high-risk population of CHD that the traditional risk factors such as the LDL-C may miss. Epidemiologists are encouraged to use this new tool to analyze other case-cohort studies and incorporate auxiliary variables embedded in the full cohort in their analysis.

Can moral reasoning be modeled in an experiment?

A review of the literature on moral issues indicates that none of the empirical approaches to moral reasoning proposes an experimental approach which controls for such object-related experimental variables as: knowledge, motivation, acceptance of moral norms and consequences of human behavior in moral situations in a single research procedure. A unique element of the proposed experimental method is a multi-stage model determining morality indicators. In the two-phase design experiment, psychology students were asked to create model ethical stories and then conduct an overall assessment of each of these stories. As a result, a base of ethical stories was created with empirical moral indicators (positive, negative, neutral). The patterns in the moral evaluation of ethical stories were determined by identifying three processes (selection, differentiation and integration). The final result is a confirmed design of the experiment and a set of formulas that can be used in education and research on morality reasoning.

Human Temporomandibular Joint Motion: A Synthesis Approach for Designing a Six-Bar Kinematic Simulator

Abstract The human earcanal can accommodate several types of in-ear devices including hearing aids, earphones, hearing protectors, and earplugs. This canal-type home has a neighbor called the temporomandibular joint (TMJ) whose movements slightly deform the shape of the earcanal. While these cyclic deformations can influence the positioning, comfort, and functioning of ear-fitted devices, they can also provide a significant amount of energy to harvest. Given their importance, the TMJ movements and earcanal deformations have been well studied. However, their mutual actions are still not fully understood. This paper presents the development of a six-bar kinematic TMJ simulator capable of replicating the complicated motion of the jaw. The development relies on a two-phase mechanism design algorithm to numerically optimize and analytically synthesize linkage mechanisms for which the classical optimization approaches cannot return a converged solution. The proposed algorithm enables the design of a kinematic simulator to generate the TMJ path with an average error as low as 1.65% while respecting all the hinge-axis parameters of the jaw. This algorithm can be subsequently used to solve nonlinear complex linkage synthesis problems, and ultimately, the developed kinematic simulator can be used to further investigate TMJ–earcanal interactions.

Professional Development and ICT: English Language Teachers’ Voices

While technology use is becoming increasingly common in education, teachers remain reluctant to use it and hesitant on how best to incorporate it into their teaching and practice. There is a strong demand from institutions for English language teachers to cope with the changing landscape of teaching in the 21st century. This explorative study investigated Hong Kong tertiary teachers’ beliefs on continuing professional development activities to enhance their teaching. The study had a two-phase research design, with an initial questionnaire (N = 58) followed by semistructured interviews (N = 12) to unpack the participants’ hidden voices. The findings illustrated that most teachers are enthusiastic about professional development activities, though there is a misalignment between what universities value and reward and what teachers see as most beneficial for enhancing their teaching practices. The results suggested that professional development activities should focus on sharing good teaching practice (e.g., informal chats, mentoring) within universities rather than on rewarding attending conferences and on-off, nonintegrated workshops.

A two-phase hybrid product design algorithm using learning vector quantization, design of experiments, and adaptive neuro-fuzzy interface systems to optimize geometric form in view of customers’ opinions

One of the most important characteristics of a modern product is the extent to which it meets the needs of customers to gain market share. The conceptual design methods of products based on customer requirements are often feature-based, in which several features are identified between different types of a product. According to customer demands, these features are tuned and the closest is selected as the optimum. The great variety of features of a present-day product can often make this difficult because finding these common features is very complicated or even impossible. To solve this problem, choosing the optimal design is divided into two phases: In the first phase, the main product is divided into some basic categories and according to the customers' opinion, one is selected as the category. In the second phase, the selection of common geometrical features between the members of the winning category is made. Then, the optimization process is done based on customer rating and the closest design to the mentioned rating is selected. The house light switch is used as a case study and the proposed algorithm is implemented on it. High customer satisfaction with the optimized final design, high response rate to survey forms, and the low number of incompatible data, all, indicate the suitability of the proposed algorithm with human interface characteristics, simplicity and efficiency in adapting the product to the customers' view. This method can be used for other industrial products and even for non-industrial products or services.

Tracking the outbreak: an optimized sequential adaptive strategy for Xylella fastidiosa delimiting surveys

The EU plant health legislation enforces the implementation of intensive surveillance programs for quarantine pests. After an outbreak, surveys are implemented to delimit the extent of the infested zone and to manage disease control. Surveillance in agricultural and natural environments can be enhanced by increasing the survey efforts. Budget constraints often limit inspection and sampling intensities, thus making it necessary to adapt and optimize surveillance strategies. A sequential adaptive delimiting survey involving a three-phase and a two-phase design with increasing spatial resolution was developed and implemented for the Xylella fastidiosa demarcated area in Alicante, Spain. Inspection and sampling intensities were optimized using simulation-based methods. Sampling intensity thresholds were evaluated by quantifying their effect on the estimation of X. fastidiosa incidence. This strategy made it possible to sequence inspection and sampling taking into account increasing spatial resolutions, and to adapt the inspection and sampling intensities according to the information obtained in the previous, coarser, spatial resolution. The proposed strategy was able to efficiently delimit the extent of Xylella fastidiosa, while improving on the efficiency and maintaining the efficacy of the official survey campaign. From a methodological perspective, our approach provides new insights into alternative delimiting designs and new reference sampling intensity values.

Reduced quality of life in ICU survivors - the story behind the numbers: A mixed methods study

To gain insight into the daily functioning of ICU survivors who reported a reduced quality of life (QoL) one year after ICU admission. A two-phase mixed method study design. QoL was assessed using the SF-36 questionnaire before admission and after one year (Phase 1). Participants reporting a reduced QoL were invited for an in-depth interview (Phase 2). Interview data were coded thematically using the PROMIS framework. Of the 797 participants, 173 (22%) reported a reduced QoL, of which 19 purposively selected patients were interviewed. In line with their questionnaire scores, most participants described their QoL as reduced. They suffered from physical, mental and/or cognitive problems, impacting their daily life, restricting hobbies, work, and social activities. A new balance in life, including relationships, had to be found. Some interviewees experienced no changes in their QoL; they were grateful for being alive, set new life priorities, and were able to accept their life with its limitations. Reduction in QoL is due to physical, mental, and cognitive health problems, restricting participants what they want to do. However, QoL was not only affected by the critical illness, but also by factors including independency, comorbidity, and life events. Registration: NCT03246334 (clinical trials.gov).

Effects of nonresponse and coverage problems on survey estimates of physical activity

To what extent do survey nonresponse and coverage problems bias estimates of physical activity? Research has focused on social desirability as a cause of observed bias but there are relatively few studies of nonresponse and coverage. I analyze data from a survey designed to allow estimation of nonresponse bias using a two-phase sampling design that resamples nonrespondents from an initial wave of telephone and IVR (interactive voice response) interviewing for follow-up face-to-face interviews. Both initial and nonresponse interview waves included measures of physical activity frequency and duration. Estimates are compared between first-round respondents and those from follow-up interviews of nonrespondents, accounting for mode and other design elements. Telephone, but not IVR, interviews were found to include bias from two sources. Findings suggest that coverage is a cause of bias in the measure of frequency of physical activity but nonresponse may bias the measure of physical activity duration.

Nonparametric inference for distribution functions with stratified samples

We consider nonparametric estimation of a distribution function when data are collected from two-phase stratified sampling without replacement. We study the inverse probability weighted empirical distribution function and propose a novel computational procedure to construct a confidence band. Two-phase sampling design induces heterogeneity across strata and dependence due to sampling without replacement. Two major statistical challenges from this design are: (1) the standard practice to approximate sampling without replacement by Bernoulli sampling leads to an incorrect coverage probability, and (2) a complicated limiting process of the proposed estimator does not allow one to analytically compute quantiles of the supremum of the limiting process nor to apply existing bootstrap methods to the proposed estimator. To address these issues, we rigorously establish the asymptotic properties of the proposed estimator and develop a simulation-based method to estimate the limiting process. The finite sample performance is evaluated through a simulation study. A Wilms tumor example is provided.

The impact of organisational values on nurse resilience: A mixed‐methods study

To investigate the impact of organisational values on nurse resilience. Nurses encounter significant occupational adversity, which can result in negative psychological consequences. Investigating the role of resilience as a protective factor focuses on what enables some nurses to positively adapt in challenging work environments. Comparatively, little attention has been paid to organisational factors and nurse resilience. A two-phase mixed-methods design comprising a cross-sectional survey and focus groups. Three hundred and ninety-four nurses responded to the survey with 25 participating in four follow-up focus groups. Significant associations were found between resilience levels and agreement with organisational values (p=.022) and agreement about the importance of values (p=.018). Three themes relating to organisational values were identified: pressures and challenges; supports and strategies; and impact of organisational values. Organisational values may positively impact resilience if nurses concur with those values and believe they are shared by their employer. To promote nurse resilience, organisations and nurse leaders should consider developing, implementing and operating with a set of employee-adopted values, which need to be demonstrably upheld across the organisation.

Reuse-centric [formula omitted]-means configuration

K-means configuration is to find a configuration of k-means (e.g., the number of clusters, feature sets) that maximize some objectives. It is a time-consuming process due to the iterative nature of k-means. This paper proposes reuse-centrick-means configuration to accelerate k-means configuration. It is based on the observation that the explorations of different configurations share lots of common or similar computations. Effectively reusing the computations from prior trials of different configurations could largely shorten the configuration time. To materialize the idea, the paper presents a set of novel techniques, including reuse-based filtering, center reuse, and a two-phase design to capitalize on the reuse opportunities on three levels: validation, number of clusters, and feature sets. Experiments on k-means–based data classification tasks show that reuse-centrick-means configuration can speed up a heuristic search-based configuration process by a factor of 5.8, and a uniform search-based attainment of classification error surfaces by a factor of 9.1. The paper meanwhile provides some important insights on how to effectively apply the acceleration techniques to tap into a full potential.

A Virtual Reality Game to Change Sun Protection Behavior and Prevent Cancer: User-Centered Design Approach.

BackgroundPublic health sun safety campaigns introduced during the 1980s have successfully reduced skin cancer rates in Australia. Despite this success, high rates of sunburn continue to be reported by youth and young adults. As such, new strategies to reinforce sun protection approaches in this demographic are needed.ObjectiveThis study aims to develop a virtual reality (VR) game containing preventive skin cancer messaging and to assess the safety and satisfaction of the design based on end user feedback.MethodsUsing a two-phase design approach, we created a prototype VR game that immersed the player inside the human body while being confronted with growing cancer cells. The first design phase involved defining the problem, identifying stakeholders, choosing the technology platform, brainstorming, and designing esthetic elements. In the second design phase, we tested the prototype VR experience with stakeholders and end users in focus groups and interviews, with feedback incorporated into refining and improving the design.ResultsThe focus groups and interviews were conducted with 18 participants. Qualitative feedback indicated high levels of satisfaction, with all participants reporting the VR game as engaging. A total of 11% (2/8) of participants reported a side effect of feeling nauseous during the experience. The end user feedback identified game improvements, suggesting an extended multistage experience with visual transitions to other environments and interactions involving cancer causation. The implementation of the VR game identified challenges in sharing VR equipment and hygiene issues.ConclusionsThis study presents key findings highlighting the design and implementation approaches for a VR health intervention primarily aimed at improving sun protection behaviors. This design approach can be applied to other health prevention programs in the future.

Depression, childhood trauma, and physical activity in older Indigenous Australians.

Indigenous Australians experience higher levels of psychological distress compared to the general population. Physical activity is a culturally acceptable approach, associated with reduction of depressive symptoms. The protective properties of physical activity for depressive symptoms are yet to be evaluated in older Indigenous Australians. A two-phase study design comprised of a qualitative thematic analysis following a quantitative regression and moderation analysis. Firstly, a total of 336 Indigenous Australians aged 60 years and over from five NSW areas participated in assessments on mental health, physical activity participation, and childhood trauma. Secondly, a focus group of seven Indigenous Australians was conducted to evaluate barriers and facilitators to physical activity. Regression and moderation analyses examined links between depression, childhood trauma, and physical activity. Thematic analysis was conducted exploring facilitators and barriers to physical activity following the focus group. Childhood trauma severity and intensity of physical activity predicted depressive symptoms. Physical activity did not affect the strength of the relationship between childhood trauma and depression. Family support and low impact activities facilitated commitment to physical activity. In contrast, poor mental health, trauma, and illness acted as barriers. Physical activity is an appropriate approach for reducing depressive symptoms and integral in maintaining health and quality of life. While situational factors, health problems and trauma impact physical activity, accessing low-impact group activities with social support was identified to help navigate these barriers.

Lifetime Prevalence and Correlates of Schizophrenia and Other Psychotic Disorders in Singapore

Introduction: The current study aimed to establish the lifetime prevalence of schizophrenia and other psychotic disorders, its sociodemographic correlates and association with physical disorders using data from the Singapore Mental Health Study (SMHS 2016).Methods: A two-phase design comprising population-level screening of psychotic symptoms using the World Health Organization Composite International Diagnostic Interview version 3.0 psychosis screen followed by clinical reappraisal based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria were used to establish the prevalence.Results: A total of 6,126 respondents completed the first phase of the study, giving a response rate of 69.5%. 5.2% (n = 326) of respondents endorsed at least one symptom in the psychosis screen. After the phase two clinical reappraisal interviews and adjusting for false-negative rate, the corrected prevalence of schizophrenia and other psychotic disorders was 2.3% (95% CI: 2.3–2.3%). The odds of having DSM-IV schizophrenia and other psychotic disorders was significantly higher among those of Malay ethnicity (OR = 3.9, 95% CI 1.4–11.0), and those who were unemployed (OR = 4.3, 95% CI 1.2–15.9). 80.4% of those with a psychotic disorder had consulted a doctor or a mental health professional for their symptoms.Conclusions: Our results indicate that approximately 2.3% of Singapore's community-dwelling adult population had a lifetime diagnosis of schizophrenia and other psychotic disorders. While the treatment gap of the disorder was relatively small, the severe nature of the disorder emphasizes the need for continued outreach and early diagnosis and treatment.

Threshold-Based Subgroup Testing in Logistic Regression Models in Two-Phase Sampling Designs

The effect of treatment on binary disease outcome can differ across subgroups characterized by other covariates. Testing for the existence of subgroups that are associated with heterogeneous treatment effects can provide valuable insight regarding the optimal treatment recommendation in practice. Our research in this paper is motivated by the question of whether host genetics could modify a vaccine's effect on HIV acquisition risk. To answer this question, we used data from an HIV vaccine trial with a two-phase sampling design and developed a general threshold-based model framework to test for the existence of subgroups associated with the heterogeneity in disease risks, allowing for subgroups based on multivariate covariates. We developed a testing procedure based on maximum of likelihood-ratio statistics over change planes and demonstrated its advantage over alternative methods. We further developed the testing procedure to account for bias sampling of expensive (i.e. resource-intensive to measure) covariates through the incorporation of inverse probability weighting techniques. We used the proposed method to analyze the motivating HIV vaccine trial data. Our proposed testing procedure also has broad applications in epidemiological studies for assessing heterogeneity in disease risk with respect to univariate or multivariate predictors.