Short run spc based upon the second order dynamic linear model for trend detection

Recently, several new applications of control chart procedures for short production runs have been introduced. Bothe (1989) and Burr (1989) proposed the use of control chart statistics which are obtained by scaling the quality characteristic by target values or process estimates of a location and scale parameter. The performance of these control charts can be significantly affected by the use of incorrect scaling parameters, resulting in either an excessive "false alarm rate," or insensitivity to the detection of moderate shifts in the process. To correct for these deficiencies, Quesenberry (1990, 1991) has developed the Q-Chart which is formed from running process estimates of the sample mean and variance. For the case where both the process mean and variance are unknown, the Q-chaxt statistic is formed from the standard inverse Z-transformation of a t-statistic. Q-charts do not perform correctly, however, in the presence of special cause disturbances at process startup. This has recently been supported by results published by Del Castillo and Montgomery (1992), who recommend the use of an alternative control chart procedure which is based upon a first-order adaptive Kalman filter model Consistent with the recommendations by Castillo and Montgomery, we propose an alternative short run control chart procedure which is based upon the second order dynamic linear model (DLM). The control chart is shown to be useful for the early detection of unwanted process trends. Model and control chart parameters are updated sequentially in a Bayesian estimation framework, providing the greatest degree of flexibility in the level of prior information which is incorporated into the model. The result is a weighted moving average control chart statistic which can be used to provide running estimates of process capability. The average run length performance of the control chart is compared to the optimal performance of the exponentially weighted moving average (EWMA) chart, as reported by Gan (1991). Using a simulation approach, the second order DLM control chart is shown to provide better overall performance than the EWMA for short production run applications     

Digital identities – overcoming visual bias through virtual embodiment

ABSTRACT

This study sheds new light on the role of identity in virtual environments when virtual representation of self is in support of disabled individuals and the potential impact of their virtual identity on work opportunities. It is widely understood that individuals who live with disability often experience a lifetime of bullying, exclusion, marginalization and rejection. They often experience workplace bias and discrimination. Yet, when they can create an identity and experience embodiment in virtual environments, the results can be extraordinarily powerful – even life-changing. This research builds on nearly a decade of ethnographic research in 3D online immersive social virtual worlds; seven of those years working with disability communities to answer the following: RQ1: In a virtual world where one can choose any avatar form, how does that visual sense of self-representation influence one’s ability to gain access to a social network, to be a leader in that network, and to find work? RQ2: How does realism in representation influence work experiences in these digital worlds? The results reveal the importance of choice in online representation of avatars in creating work and online social engagement. Implications contribute to our understanding of visual bias in the workplace and how emerging virtual reality technologies may open new avenues for meaningful work and social interactions for people with disabilities.     

Sibship and Inequality Beliefs: Do Siblings Have a Liberalizing or Conservatizing Effect?

How do individuals come to hold certain beliefs about meritocracy, individualism, and redistribution? Several sociodemographic factors are regularly used to understand variation in these beliefs, but other predictors remain untested. Meanwhile, scholars studying family dynamics are increasingly turning their attention toward the long-term social effects of distinct family features. One facet of this work focuses on the social role of siblings. We investigate the relationship at the intersection of these literatures. How does growing up with (more) siblings influence one's inequality beliefs? Do siblings promote collectivism or might these same relationships foster competition and individualism? Could trust be the mechanism connecting sibship size with inequality beliefs? Or, do sibling effects reflect a broader promotion of conservative thinking in larger families? We investigate these questions using data from the General Social Survey from 1984 to 2018. Our results indicate that siblings are associated with more conservative meritocracy beliefs. On the other hand, we find limited evidence of siblings influencing attitudes toward redistribution.     

On three and four vicious walkers

We establish a reflection principle for three lattice walkers and use this principle to reduce the enumeration of configurations of three vicious walkers to the enumeration of configurations of two vicious walkers. More precisely, the reflection principle leads to a bijection between three walks (L₁, L₂, L₃) such that L₂ intersects both L₁ and L₃ and three walks (L₁, L₂, L₃) such that L₁ intersects L₃. Hence we find a combinatorial interpretation of the formula for the generating function for the number of configurations of three vicious walkers, originally derived by Bousquet-Mélou by using the kernel method, and independently by Gessel by using tableaux and symmetric functions. This answers a question posed by Gessel and Bousquet-Mélou. We also find a reflection principle for four vicious walks that leads to a combinatorial interpretation of a formula derived from Gessel's theorem.     

Cost Allocation in Manufacturing–Remanufacturing Operations

For firms remanufacturing their products, the total life‐cycle costs and revenues from new and remanufactured products determine their profitability. In many firms, manufacturing/sales and remanufacturing/remarketing operations are carried out in different divisions. Each division is responsible for only part of the product's life cycle. Practices regarding transfer pricing across divisions vary significantly among companies, affecting the life‐cycle profit performance of the product. In this research, we identify characteristics of transfer prices that achieve the firm‐wide optimal solution. To this end, we consider a manufacturer who also undertakes remanufacturing operations and we focus on price (quantity) decisions. We determine that a cost allocation mechanism that allocates a portion of the initial production cost to each of the two stages of the product life cycle should be used. We also conclude that cost allocation should be implemented as a fixed cost allocation, where charges to the remanufacturing division should be determined independently of the actual quantity of units remanufactured.     

The Social Vulnerability Scale for Older Adults: An Exploratory and Confirmatory Factor Analytic Study

The Social Vulnerability Scale (SVS), a 22-item informant report of vulnerability to exploitation and, in particular, financial exploitation of older adults, was administered to 266 respondents who assessed the social vulnerability of a significant other aged 50 years or over, either a person with dementia or other neurological condition (n?=?116), or a healthy adult (n?=?150). Exploratory factor analysis in the combined sample revealed a 15-item two-factor solution labeled gullibility and credulity. Stability in factor structure was established in an independent sample (n?=?123) using confirmatory factor analysis, and sound reliability (internal consistency) and validity (known-groups) were demonstrated. The SVS15 is a potentially useful instrument for assessing older adults' vulnerability to exploitation.     

“Do They Think I Am a Pack Rat?”

This case study presents details of the life of one older man who lived in seclusion and squalor, surrounded by hoarded possessions. This man was one participant of a focused ethnography of eight older adults who received home care. All participants in the original ethnography were identified by their community care coordinators as exhibiting hoarding behaviors. The case study presented here provides rich narrative and photographic detail in order to add strength to what has already been presented in previous research articles about compulsive acquisition. The narratives reveal examples of debilitating dysfunction, distress associated with decision making, broad acquisition of free things, compulsive buying, and ritualistic discarding. Quotes included in the case study stem from the original ethnography.     

A Day at the Zoo Through the Lens of Jessica Benjamin's Bonds of Love

In this photo-based essay I bring Jessica Benjamin's project of transforming relationships of domination to a day at the zoo. The interrogation of the human/animal dualism illuminates relational moments of mutuality across species. Managing the tension between sameness and difference without collapse into hierarchical configuration, the human-animal connection may take its place in the project of transforming relationships of domination and extending the circle of ethical care.     

Social Workers’ Attitudes Toward Older Adults: A Review of the Literature

Ageist attitudes toward older adults have been recognized as barriers to recruiting and training competent social workers. This article provides a systematic review of the literature that focused on social workers’ and social work students’ attitudes toward older adults and working with older adults. The authors sought empirical studies that used an attitudinal measure of ageism with a social work sample, and a total of 20 articles met the criteria. Characteristics of the studies’ participants, methodology, instruments, and results were evaluated. This article discusses the findings and offers implications for future research.