Recognizing Structural Nonidentifiability: When Experiments Do Not Provide Information About Important Parameters and Misleading Models Can Still Have Great Fit

In the quest to model various phenomena, the foundational importance of parameter identifiability to sound statistical modeling may be less well appreciated than goodness of fit. Identifiability concerns the quality of objective information in data to facilitate estimation of a parameter, while nonidentifiability means there are parameters in a model about which the data provide little or no information. In purely empirical models where parsimonious good fit is the chief concern, nonidentifiability (or parameter redundancy) implies overparameterization of the model. In contrast, nonidentifiability implies underinformativeness of available data in mechanistically derived models where parameters are interpreted as having strong practical meaning. This study explores illustrative examples of structural nonidentifiability and its implications using mechanistically derived models (for repeated presence/absence analyses and dose–response of Escherichia coli O157:H7 and norovirus) drawn from quantitative microbial risk assessment. Following algebraic proof of nonidentifiability in these examples, profile likelihood analysis and Bayesian Markov Chain Monte Carlo with uniform priors are illustrated as tools to help detect model parameters that are not strongly identifiable. It is shown that identifiability should be considered during experimental design and ethics approval to ensure generated data can yield strong objective information about all mechanistic parameters of interest. When Bayesian methods are applied to a nonidentifiable model, the subjective prior effectively fabricates information about any parameters about which the data carry no objective information. Finally, structural nonidentifiability can lead to spurious models that fit data well but can yield severely flawed inferences and predictions when they are interpreted or used inappropriately.     

Compulsory income management: Combatting or compounding the underlying causes of homelessness?

Compulsory Income Management (CIM) is a form of conditional welfare that involves the mandatory quarantining of a portion of welfare recipients’ social security payments. Quarantined funds are accessible via a government-issued debit card, with restrictions surrounding where and on what funds can be spent. Official justifications of CIM have framed these policies as attempts to combat substance abuse and gambling problems, and to thus secure better outcomes for welfare recipients and their families. Central to this narrative has been the argument that welfare quarantining will ensure more money is spent on ‘essentials’, including accommodation. No existing studies, however, have specifically interrogated the impacts of CIM on housing security. This article responds to this gap in the literature by reviewing existing research concerning CIM's impacts and locating this research within broader debates regarding the causes of homelessness and the efficacy of individualised policy interventions. In doing so, it highlights CIM's potential to exacerbate housing insecurity not only through technical issues such as rental transfer failures, but also by contributing to underlying stressors such as economic disadvantage; relationship difficulties, poor health and addiction; and social stigma. The article concludes that – far from addressing the structural causes of homelessness – CIM has enflamed them.     

Labour Market Realism and the Global Compacts on Migration and Refugees

The Global Compacts on Migration (GCM) and Refugees (GCR) include policy recommendations that aim to increase opportunities for legal labour migration, improve protections for migrant workers, and provide refugees with ‘complementary pathways’ to enhanced protection via labour mobility. This paper explains why there are large gaps between these policy recommendations and the labour market policies and realities in the countries that host most of the world’s migrant workers. These gaps between ideals and realities are likely to limit the effective implementation of the GCM/GCR recommendations on labour migration. More ‘labour market realism‘ is needed to incrementally but effectively improve protections for migrant workers.     

Rank aggregation using latent-scale distance-based models

Rank aggregation aims at combining rankings of a set of items assigned by a sample of rankers to generate a consensus ranking. A typical solution is to adopt a distance-based approach to minimize the sum of the distances to the observed rankings. However, this simple sum may not be appropriate when the quality of rankers varies. This happens when rankers with different backgrounds may have different cognitive levels of examining the items. In this paper, we develop a new distance-based model by allowing different weights for different rankers. Under this model, the weight associated with a ranker is used to measure his/her cognitive level of ranking of the items, and these weights are unobserved and exponentially distributed. Maximum likelihood method is used for model estimation. Extensions to the cases of incomplete rankings and mixture modeling are also discussed. Empirical applications demonstrate that the proposed model produces better rank aggregation than those generated by Borda and the unweighted distance-based models.

     

The managerial power approach: Is it testable?

Journal of Management and Governance - The central hypothesis of the managerial power approach (MPA) states that power is the main driver of executive compensation. The positive impact of power on...     

The Congruence Between Adolescents and Their Parents’ Gender-Role Attitudes in Urban Slums of Allahabad,India

Gender role differentiation intensifies during adolescence. The current study explores gender-role attitudes among unmarried young men and women aged 15–21 residing in the slums of Allahabad, India. The survey asked a series of questions about gender role attitudes to young men and women and to their parents (relating to work and educational attainment for girls, marriage and husband–wife relations). Since either the father or mother responded to the parent questionnaire, data analyses are based on subsets of mother–daughter pairs (n = 2124), mother–son pairs (n = 2135), father–son pairs (n = 788), and father–daughter pairs (n = 452). No significant differences emerged in terms of adolescent background characteristics of the four groups and the adolescent population of the study. A fair amount of congruence in gender role attitudes was found in the mother–daughter and father–son pairs for most items. However, a similar pattern was not visible in the father–daughter or mother–son pairs. Multivariate regression analysis indicated strong influence of parental attitudes on the adolescent’s attitudes. While education led to a shift in girls’ attitudes to gender egalitarian ones, it did not impact the attitudes of adolescent boys.     

To live an ordinary life: resource needs and additional costs for people with a physical impairment

Disabled people face increased risks of living in poverty largely due to lower incomes and extra resource requirements compared to non-disabled people. This study incorporated the social model of disability with an economic approach to costing to estimate the additional costs required by people with a physical impairment to achieve an adequate standard of living in New Zealand. Budgets estimating the additional equipment, modifications, transport, support and time required to achieve an adequate standard of living were developed and validated through focus groups with community members. The findings suggest that reducing barriers involves substantial costs ranging from NZ$645–$2,348 per week.     

Workplace Flexibility Practices and Corporate Performance: Evidence from the British Private Sector

This paper investigates the relationship between workplace flexibility practices (WFPs) and corporate performance using data from the British Workplace Employment Relations Survey 2004. Disaggregating WFPs into numerical, functional and cost aspects enables the analysis of their relationships to an objective measure of corporate performance, namely workplace financial turnover. Furthermore separate analyses are presented for different types of workplace: differentiated by workforce size; ownership; age; wage level; and unionization. Results show that different types of workplaces need to pay attention to the mix of WFPs they adopt. We find that certain cost WFPs (profit‐related pay, merit pay and payment‐by‐results) have strong positive relationships with corporate performance. However, training delivers mixed corporate performance results, while the extent of job autonomy and the proportion of part‐time employees in a workplace have an inverse association with corporate performance. Given the limited existing research examining disaggregated measures of WFPs and objectively measured corporate performance, this paper offers useful insights for firms, policy makers and the overall economy.