Home About us Contact
|
Home About us Contact | ||
|
|
||
Appropriate Adjustments (appropriate + adjustment)
Selected AbstractsMulti-block and path modelling proceduresJOURNAL OF CHEMOMETRICS, Issue 11-12 2008Agnar Höskuldsson Abstract The author has developed a unified theory of path and multi-block modelling of data. The data blocks are arranged in a directional path. Each data block can lead to one or more data blocks. It is assumed that there is given a collection of input data blocks. Each of them is supposed to describe one or more intermediate data blocks. The output data blocks are those that are at the ends of the paths and have no succeeding data blocks. The optimisation procedure finds weights for the input data blocks so that the size of the total loadings for the output data blocks are maximised. When the optimal weight vectors have been determined, the score and loading vectors for the data blocks in the path are determined. Appropriate adjustment of the data blocks is carried out at each step. Regression coefficients are computed for each data block that show how the data block is estimated by data blocks that lead to it. Methods of standard regression analysis are extended to this type of modelling. Three types of ,strengths' of relationship are computed for each set of two connected data blocks. First is the strength in the path, second the strength where only the data blocks leading to the last one are used and third if only the two are considered. Cross-validation and other standard methods of linear regression are carried out in a similar manner. In industry, processes are organised in different ways. It can be useful to model the processes in the way they are carried out. By proper alignment of sub-processes, overall model can be specified. There can be several useful path models during the process, where the data blocks in a path are the ones that are actual or important at given stages of the process. Data collection equipments are getting more and more advanced and cheap. Data analysis need to ,catch up' with the challenges that these new technology provides with. Copyright © 2008 John Wiley & Sons, Ltd. [source] Assessing the validity of potential alcohol-related non-fatal injury indicatorsADDICTION, Issue 3 2008John Langley ABSTRACT Aim To assess critically the face validity of the World Health Organization's (WHO's) International Guide for Monitoring Alcohol Consumption and Related Harm (MACRH) for deriving indicators, for the purposes of developing non-fatal alcohol-related injury indicators in New Zealand. Design MACRH's five solutions for deriving indicators are: (i) use only alcohol-specific cases; (ii) identify subsets of events known to be highly alcohol-related; (iii) utilize control indicators that are rarely alcohol-related; (iv) estimate alcohol attributable fractions (AAFs) and adjust indicators accordingly; and (v) develop composite indicators. These were assessed in terms of their face validity with particular reference to New Zealand. Findings There are significant face validity issues with each of the five options. Solution 4 offers the greatest promise, provided that: (i) valid AAFs can be derived and they are updated regularly; and (ii) appropriate adjustment is made for extraneous influences on the estimates of alcohol-related harm. To date, the latter has not been carried out. Conclusions Most potential sources of data on alcohol-related harm are subject to extraneous influences, which vary over time and space. While the attempt by WHO to offer solutions to this problem is laudable, the solutions do not address the problem adequately. MACRH guidelines need to be revised to include criteria for a valid outcome indicator. [source] Non-local damage model based on displacement averagingINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 1 2005M. Jirįsek Abstract Continuum damage models describe the changes of material stiffness and strength, caused by the evolution of defects, in the framework of continuum mechanics. In many materials, a fast evolution of defects leads to stress,strain laws with softening, which creates serious mathematical and numerical problems. To regularize the model behaviour, various generalized continuum theories have been proposed. Integral-type non-local damage models are often based on weighted spatial averaging of a strain-like quantity. This paper explores an alternative formulation with averaging of the displacement field. Damage is assumed to be driven by the symmetric gradient of the non-local displacements. It is demonstrated that an exact equivalence between strain and displacement averaging can be achieved only in an unbounded medium. Around physical boundaries of the analysed body, both formulations differ and the non-local displacement model generates spurious damage in the boundary layers. The paper shows that this undesirable effect can be suppressed by an appropriate adjustment of the non-local weight function. Alternatively, an implicit gradient formulation could be used. Issues of algorithmic implementation, computational efficiency and smoothness of the resolved stress fields are discussed. Copyright © 2005 John Wiley & Sons, Ltd. [source] Maternal hypothyroidism in early and late gestation: effects on neonatal and obstetric outcomeCLINICAL ENDOCRINOLOGY, Issue 5 2005Iskandar Idris Summary Background, Maternal hypothyroidism may be associated with a variety of adverse neonatal and obstetric outcomes. Whether these outcomes are affected by maternal thyroid status at initial presentation or in late gestation specifically within a dedicated antenatal endocrine clinic remains unclear. The effects of thyroxine dose requirement during pregnancy and serum concentrations of TSH within such clinic settings are still not known. Objectives, We investigated these outcomes in patients with hypothyroidism during early and late gestation. TSH levels and thyroxine dose requirement during early and late gestation were also evaluated. Methods, We performed a retrospective study of data from 167 pregnancies managed in the antenatal endocrine clinic. Analysis of outcomes was linked to TSH at first presentation and in the third trimester. Outcome variables included: rate of caesarean section, pre-eclampsia, neonatal unit admission, neonatal weight and gestational age. Controlled TSH was defined as mothers with TSH between 0·1 and 2 with normal free thyroid hormone levels. Results, The caesarean section (CS) rates were higher in the study cohort (H) compared with the local (C) rate (H = 28·7%, C = 18%). The higher rate in our patient cohort was not due to a higher rate of emergency section nor to a lower threshold for performing elective caesarean section. The infant birthweight (IBW) from mothers with TSH > 5·5 (H1) and mothers with TSH between 0·1 and 5·5 at presentation (H2) was [median (range)] 3·38 (1·73,4·70) vs. 3·45 (1·36,4·76); P = ns. The prevalence of low-birthweight (LBW) infants (< 2·5 g) in groups H1 and H2 was 15% and 4·8%, respectively [odds ratio (OR) = 3·55, 95% confidence interval (95% CI) = 0·96,10·31]. IBW from mothers with TSH > 2 (H3) and mothers with controlled TSH in the third trimester (H4) were similar [3·38 (1·78,4·4) vs. 3·46 (1·36,4·76); P = ns]. The prevalence of LBW in groups H3 and H4 was 9% and 4·9%, respectively (OR = 1·95, 95% CI = 0·52,7·26). The median thyroxine dose (µg) increased significantly during pregnancy (first trimester: 100; second trimester: 125, P < 0·001; and third trimester: 150, P < 0·001) associated with appropriate suppression of TSH levels in the second and third trimesters. Rates of pre-eclampsia or admissions to neonatal units were negligible. Conclusion, Thyroxine dose requirement increases during pregnancy and thus close monitoring of thyroid function with appropriate adjustment of thyroxine dose to maintain a normal serum TSH level is necessary throughout gestation. Within a joint endocrine,obstetric clinic, maternal hypothyroidism at presentation and in the third trimester may increase the risk of low birthweight and the likelihood for caesarean section. The latter observation was not due to a higher rate of emergency caesarean section nor to a lower threshold for performing elective caesarean section. A larger study with adjustments made for the various confounders is required to confirm this observation. [source] GLOBAL EVIDENCE ON THE EQUITY RISK PREMIUMJOURNAL OF APPLIED CORPORATE FINANCE, Issue 4 2003Elroy Dimson The size of the equity risk premium,the incremental return that shareholders require to hold risky equities rather than risk-free securities,is a key issue in corporate finance. Financial economists generally measure the equity premium over long periods of time in order to obtain reliable estimates. These estimates are widely used by investors, finance professionals, corporate executives, regulators, lawyers, and consultants. But because the 20th century proved to be a period of such remarkable growth in the U.S. economy, estimates of the risk premium that rely on past market performance may be too high to serve as a reliable guide to the future. The authors analyze a 103-year history of risk premiums in 16 countries and conclude that the U.S. risk premium relative to Treasury bills was 5.3% for that period,lower than previous studies suggest,as compared to 4.2% for the U.K. and 4.5% for a world index. But the article goes on to observe that the historical record may still overstate expectations of the future risk premium, partly because market volatility in the future may be lower than in the past, and partly because of a general decline in risk resulting from new technological advances and increased diversification opportunities for investors. After adjusting for the expected impact of these factors, the authors calculate forward-looking equity risk premiums of 4.3% for the U.S., 3.9% for the U.K., and 3.5% for the world index. At the same time, however, they caution that the risk premium can fluctuate over time and that managers should make appropriate adjustments when there are compelling economic reasons to think that expected premiums are unusually high or low. [source] The Role of Process Evaluation in the Training of Facilitators for an Adolescent Health Education ProgramJOURNAL OF SCHOOL HEALTH, Issue 4 2000Deborah Helitzer ABSTRACT: This article reports on the process evaluation of the training of facilitators for the Adolescent Social Action Program, a health education program in Albuquerque, New Mexico that trained college students and adult volunteers to work with middle school students. From the process evaluation data collected throughout a four-year period (1995,1998), data relevant to training are described: facilitator characteristics, facilitator training, curriculum implementation, and use of the program's model designed to promote critical thinking and dialogue. Results indicated that, though most facilitators reported the training was sufficient to enable them to implement the curriculum, they did not completely do so, especially as groups reached their final sessions. Facilitators covered the core curriculum content, but often failed to follow through with the more abstract activities. The need to perform and report the process evaluation in time to provide ample opportunity for trainers and curriculum designers to make appropriate adjustments is discussed. [source] Oxidative gating of water channels (aquaporins) in Chara by hydroxyl radicalsPLANT CELL & ENVIRONMENT, Issue 9 2004T. HENZLER ABSTRACT Hydroxyl radicals (*OH) as produced in the Fenton reaction (Fe2+ + H2O2 = Fe3+ + OH, + *OH) have been used to reversibly inhibit aquaporins in the plasma membrane of internodes of Chara corallina. Compared to conventional agents such as HgCl2, *OH proved to be more effective in blocking water channels and was less toxic to the cell. When internodes were treated for 30 min, cell hydraulic conductivity (Lp) decreased by 90% or even more. This effect was reversed within a few minutes after removing the radicals from the medium. In contrast to HgCl2, radical treatment reduced membrane permeability of small lipophilic organic solutes (ethanol, acetone, 1-propanol, and 2-propanol) by only 24 to 52%, indicating some continued limited movement of these solutes across aquaporins. The biggest effect of *OH treatment on solute permeability was found for isotopic water (HDO), which largely used water channels to cross the membrane. Inhibition of aquaporins reduced the diffusional water permeability (Pd) by about 70%. For the organic test solutes, which mainly use the bilayer to cross the membrane, channel closure caused anomalous (negative) osmosis; that is, cells had negative reflection coefficients (,s) and were transiently swelling in a hypertonic medium. From the ratio of bulk (Lp or osmotic permeability coefficient, Pf) to diffusional (Pd) permeability of water, the number (N) of water molecules that align in water channels was estimated to be N = Pf/Pd = 46 (on average). Radical treatment decreased N from 46 to 11, a value still larger than unity, which would be expected for a membrane lacking pores. The gating of aquaporins by *OH radicals is discussed in terms of a direct action of the radicals when passing the pores or by an indirect action via the bilayer. The rapid recovery of inhibited channels may indicate an easy access of cytoplasmic antioxidants to closed water channels. As hydrogen peroxide is a major signalling substance during different biotic and abiotic stresses, the reversible closure of water channels by *OH (as produced from H2O2 in the apoplast in the presence of transition metals such as Fe2+ or Cu+) may be downstream of the H2O2 signalling. This may provide appropriate adjustments in water relations (hydraulic conductivity), and a common response to different kinds of stresses. [source] Modeling Na clusters in Ar matricesANNALEN DER PHYSIK, Issue 7 2005F. Fehrer Abstract We present a microscopic model for Na clusters embedded in raregas matrices. The valence electrons of the Na cluster are described by time-dependent density-functional theory at the level of the local-density approximation (LDA). Particular attention is paid to the semi-classical picture in terms of Vlasov-LDA. The Na+ ions and Ar atoms are handled as classical particles whereby the Ar atoms carry two degrees of freedom, position and dipole polarization. The interaction between Na+ ions and electrons is mediated through local pseudo-potentials. The coupling to the Ar atoms is described by (long-range) polarization potentials and (short-range) repulsive cores. The ingredients are taken from elsewhere developed standards. A final fine-tuning is performed using the NaAr molecule as benchmark. The model is then applied to embedded systems Na8ArN. By close comparison with quantum-mechanical results, we explore the capability of the Vlasov-LDA to describe such embedded clusters. We show that one can obtain a reasonable description by appropriate adjustments in the fine-tuning phase of the model. [source] Statistical Inference For Risk Difference in an Incomplete Correlated 2 × 2 TableBIOMETRICAL JOURNAL, Issue 1 2003Nian-Sheng Tang Abstract In some infectious disease studies and 2-step treatment studies, 2 × 2 table with structural zero could arise in situations where it is theoretically impossible for a particular cell to contain observations or structural void is introduced by design. In this article, we propose a score test of hypotheses pertaining to the marginal and conditional probabilities in a 2 × 2 table with structural zero via the risk/rate difference measure. Score test-based confidence interval will also be outlined. We evaluate the performance of the score test and the existing likelihood ratio test. Our empirical results evince the similar and satisfactory performance of the two tests (with appropriate adjustments) in terms of coverage probability and expected interval width. Both tests consistently perform well from small- to moderate-sample designs. The score test however has the advantage that it is only undefined in one scenario while the likelihood ratio test can be undefined in many scenarios. We illustrate our method by a real example from a two-step tuberculosis skin test study. [source] Contribution of birth defects to infant mortality in the United StatesBIRTH DEFECTS RESEARCH, Issue S1 2002Joann Petrini Background While overall infant mortality rates (IMR) have declined over the past several decades, birth defects have remained the leading cause of infant death in the United States. To illustrate how this leading cause of infant mortality impacts subgroups within the US population a descriptive analysis of the contribution of birth defects to infant mortality at the national and state level was conducted. Methods Descriptive analyses of birth defects-specific IMRs and proportionate infant mortality due to birth defects were conducted for the US using 1999 mortality data from the National Center for Health Statistics. In 1999, the change to ICD-10 impacted how cause-specific mortality rates were coded. Aggregated 1995-1998 state- birth defects infant death statistics were used for state comparisons. Results In 1999, birth defects accounted for nearly 1 in 5 infant deaths in the US. Variation in birth defects-specific IMRs were observed by maternal race with black infants having the highest rates when compared with other race groups. However, among black infants prematurity/low birthweight was the leading cause of death, followed by birth defects. There is substantial variation in state-specific birth defects IMRs and the state-specific proportion of infant deaths due to birth defects. Conclusions Birth defects remain the leading cause of infant death in the United States, despite the changes that resulted in 1999 from an update in the coding of cause of death from ICD-9 to ICD-10. While birth defects-specific IMRs provide an overall picture of fatal birth defects and a gauge of the impact of life-threatening anomalies, they represent only a fraction of the impact of birth defects, missing those who survive past infancy and those birth defects related losses in the antepartum period. Expansion and support of effective birth defects monitoring systems in each state that include the full spectrum of perinatal outcomes must be a priority. However, paralleling these efforts, analyses of this leading cause of infant mortality provide critical insight into perinatal health and should continue, with appropriate adjustments for the 1999 classification changes. Teratology 66:S3,S6, 2002. © 2002 Wiley-Liss, Inc. [source] The ethics of creative accounting some Spanish evidenceBUSINESS ETHICS: A EUROPEAN REVIEW, Issue 3 2000John Blake Creative accounting involves accountants in making accounting policy choices or manipulating transactions in such a way as to convey a preferred and deliberately chosen impression in the accounts. Although it is regarded as unethical by most observers, a defense of creative accounting can be based on the assumption that users of accounts can identify bias in accounting policy choices and make appropriate adjustments. In this paper we take the example of the Barcelona Football Club where the club management made three key accounting policy choices that resulted in the presentation of a favourable position, and a supporters club presented an alternative report choosing three alternative accounting policies that presented an unfavourable position. We presented each of these financial reports to one of two groups of Spanish bank loan officers: we found that the more favourable set of accounts was significantly more likely to attract a positive response to a loan request. This result undermines the validity of defending creative accounting based on the argument that accounts users can identify manipulation. [source] | ||||||||||||||||