Further exploratory analysis of split-plot experiments to study certain stratified effects

Designed experiments are a key component in many companies' improvement strategies. Because completely randomized experiments are not always reasonable from a cost or physical perspective, split-plot experiments are prevalent. The recommended analysis accounts for the different sources of variation affecting whole-plot and split-plot error. However experiments on industrial processes must be run and, consequently analyzed quite differently from ones run in a controlled environment. Such experiments are typically subject to a wide array of uncontrolled, and barely understood, variation. In particular, it is important to examine the experimental results for additional, unanticipated sources of variation. In this paper, we consider how unanticipated, stratified effects may influence a split-plot experiment and discuss further exploratory analysis to indicate the presence of stratified effects. Examples of such experiments are provided, additional tests are suggested and discussed in light of their power, and recommendations given.     

Variability in PAH-DNA Adduct Measurements in Peripheral Mononuclear Cells: Implications for Quantitative Cancer Risk Assessment

Biomarkers such as DNA adducts have significant potential to improve quantitative risk assessment by characterizing individual differences in metabolism of genotoxins and DNA repair and accounting for some of the factors that could affect interindividual variation in cancer risk. Inherent uncertainty in laboratory measurements and within-person variability of DNA adduct levels over time are putatively unrelated to cancer risk and should be subtracted from observed variation to better estimate interindividual variability of response to carcinogen exposure. A total of 41 volunteers, both smokers and nonsmokers, were asked to provide a peripheral blood sample every 3 weeks for several months in order to specifically assess intraindividual variability of polycyclic aromatic hydrocarbon (PAH)-DNA adduct levels. The intraindividual variance in PAH-DNA adduct levels, together with measurement uncertainty (laboratory variability and unaccounted for differences in exposure), constituted roughly 30% of the overall variance. An estimated 70% of the total variance was contributed by interindividual variability and is probably representative of the true biologic variability of response to carcinogenic exposure in lymphocytes. The estimated interindividual variability in DNA damage after subtracting intraindividual variability and measurement uncertainty was 24-fold. Inter-individual variance was higher (52-fold) in persons who constitutively lack the Glutathione S-Transferase M1 (GSTM1) gene which is important in the detoxification pathway of PAH. Risk assessment models that do not consider the variability of susceptibility to DNA damage following carcinogen exposure may underestimate risks to the general population, especially for those people who are most vulnerable.     

Autonomy in Everyday Life,for Whom?

A disability reform came into force in Sweden in 1994 which emphasises the importance for disabled people to increased autonomy and self determination in everyday life. Interviews with disabled women and men have shown that while there are those who, because of the legislation, have increased control in their everyday living, there are also those who in no way have benefited from this reform. Some of the disabled participants have not even heard of the legislation before the time of the interview. They are in a situation that they require support, which they do not have, in order to apply for services of their choice and, if necessary, appeal against 'negative' decisions with regard to the applied for services. The paper concludes with a discussion about the Janus-faced nature of individual rights.     

Vitamin D and the postmenopausal population

Vitamin D, a hormone critical to the body's maintenance of serum calcium and phosphorus concentrations, is currently the subject of much scientific interest. Low levels of vitamin D have been observed in many populations and epidemiological studies have suggested a link between this biochemical state and a range of diseases, such as cancer, diabetes and multiple sclerosis. While the consequence of vitamin D deficiency is well documented for bone (rickets and osteomalacia), with mixed findings relating to falls and fractures, a causal link between vitamin D deficiency and these wider health outcomes has not been established. If these relationships were found to be causal, the morbidity and mortality resulting from low levels of vitamin D could be substantial; the current evidence base, however, most robustly supports the assessment of serum 25(OH)-vitamin D in the context of specific symptoms, low bone mineral density or biochemical abnormalities, rather than as an entity to treat in its own right or as the basis for a population-wide screening programme.     

Are nurses more altruistic than real estate brokers?

We report results from a dictator game experiment with nurse students and real estate broker students as dictators, and Amnesty International as the recipient. Although brokers contributed substantial amounts, nurses contributed significantly more, on average 76% of their endowment. In a second part, subjects chose between a certain repetition of the experiment and a 50-50 chance of costly exit. About one third of the brokers and half of the nurses chose the exit option. While generosity was indeed higher among nurses, even when taking exits into account, the difference cannot readily be attributed to different degrees of altruism.     

Victim of and witness to violence: an interactional perspective on mothers' perceptions of children exposed to intimate partner violence

This article reports a study of how mothers perceive the effects of intimate partner violence (IPV) during pregnancy and children's exposure to IPV: (a) Do interactional aspects of IPV have a negative impact on the fetus during pregnancy or on the newborn baby? and (b) Is there a relationship between interactional aspects of IPV and (a) children's risk of being exposed to IPV and (b) the age of the child when at risk for exposure to IPV? A representative sample of 137 IPV help-seeking mothers in Norway was interviewed. Severity of physical IPV and injury from sexual IPV increased the risk of consequences to the fetus. Frequency of physical and psychological IPV increased the likelihood of children's exposure. Duration of the partnership increased the risk of children's exposure to physical and sexual IPV. Finally, there was a negative linear association between children's age when exposed for the first time and frequency of physical and psychological IPV.     

‘IF I FEEL LIKE THIS,HOW DOES THE CHILD FEEL?’ CHILD PROTECTION WORKERS,SUPERVISION, MANAGEMENT AND ORGANISATIONAL RESPONSES TO PARENTAL VIOLENCE

This study analysed workers’ experiences of supervision following interactions with hostile and intimidating parents. This analysis examined management and organisational responses to worker stress, and assessed the adequacy of support that workers received. An online survey was designed to collect data on workers’ experiences and free text responses were qualitatively analysed for references to the supervision they received in response to working with parents. 590 participants responded to the survey. 402 were qualified social workers, and 423 worked in child protection. Participants had experienced a range of violent behaviour from parents. The overwhelming theme in responses was the lack of support and supervision workers received, often in stressful and frightening circumstances. Approximately one quarter of participants only used organisational procedures, guidelines or protocols on dealing with hostile parents. Workers reported that mismanaged parental hostility affected their practice and the quality of protection that children received. The violence experienced had a significant negative impact on their personal and professional lives. Organisational responses in the form of supervision and education were often inadequate and resulted in children receiving reduced quality of protection. Recommendations for policy and practice change are discussed, with the aim of caring for workers and the children they protect.