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Analytic Methods (analytic + methods)
Selected AbstractsMasked intervention effects: Analytic methods for addressing low dosage of interventionNEW DIRECTIONS FOR EVALUATION, Issue 110 2006John E. Lochman This chapter describes potential drawbacks of using intent-to-treat (ITT) analyses to examine intervention effects and presents several additional analytic methods as alternatives to ITT. [source] Statistical methods for longitudinal research on bipolar disordersBIPOLAR DISORDERS, Issue 3 2003John Hennen Objectives: Outcomes research in bipolar disorders, because of complex clinical variation over-time, offers demanding research design and statistical challenges. Longitudinal studies involving relatively large samples, with outcome measures obtained repeatedly over-time, are required. In this report, statistical methods appropriate for such research are reviewed. Methods: Analytic methods appropriate for repeated measures data include: (i) endpoint analysis; (ii) endpoint analysis with last observation carried forward; (iii) summary statistic methods yielding one summary measure per subject; (iv) random effects and generalized estimating equation (GEE) regression modeling methods; and (v) time-to-event survival analyses. Results: Use and limitations of these several methods are illustrated within a randomly selected (33%) subset of data obtained in two recently completed randomized, double blind studies on acute mania. Outcome measures obtained repeatedly over 3 or 4 weeks of blinded treatment in active drug and placebo sub-groups included change-from-baseline Young Mania Rating Scale (YMRS) scores (continuous measure) and achievement of a clinical response criterion (50% YMRS reduction). Four of the methods reviewed are especially suitable for use with these repeated measures data: (i) the summary statistic method; (ii) random/mixed effects modeling; (iii) GEE regression modeling; and (iv) survival analysis. Conclusions: Outcome studies in bipolar illness ideally should be longitudinal in orientation, obtain outcomes data frequently over extended times, and employ large study samples. Missing data problems can be expected, and data analytic methods must accommodate missingness. [source] Stochastic matrix models for conservation and management: a comparative review of methodsECOLOGY LETTERS, Issue 3 2001John Fieberg Stochastic matrix models are frequently used by conservation biologists to measure the viability of species and to explore various management actions. Models are typically parameterized using two or more sets of estimated transition rates between age/size/stage classes. While standard methods exist for analyzing a single set of transition rates, a variety of methods have been employed to analyze multiple sets of transition rates. We review applications of stochastic matrix models to problems in conservation and use simulation studies to compare the performance of different analytic methods currently in use. We find that model conclusions are likely to be robust to the choice of parametric distribution used to model vital rate fluctuations over time. However, conclusions can be highly sensitive to the within-year correlation structure among vital rates, and therefore we suggest using analytical methods that provide a means of conducting a sensitivity analysis with respect to correlation parameters. Our simulation results also suggest that the precision of population viability estimates can be improved by using matrix models that incorporate environmental covariates in conjunction with experiments to estimate transition rates under a range of environmental conditions. [source] Seizure Outcome after Temporal Lobectomy: Current Research Practice and FindingsEPILEPSIA, Issue 10 2001A. M. McIntosh Summary: ,Purpose: The literature regarding seizure outcome and prognostic factors for outcome after temporal lobectomy is often contradictory. This is problematic, as these data are the basis on which surgical decisions and counseling are founded. We sought to clarify inconsistencies in the literature by critically examining the methods and findings of recent research. Methods: A systematic review of the 126 articles concerning temporal lobectomy outcome published from 1991 was conducted. Results: Major methodologic issues in the literature were heterogeneous definitions of seizure outcome, a predominance of cross-sectional analyses (83% of studies), and relatively short follow-up in many studies. The range of seizure freedom was wide (33,93%; median, 70%); there was a tendency for better outcome in more recent studies. Of 63 factors analyzed, good outcome appeared to be associated with several factors including preoperative hippocampal sclerosis, anterior temporal localization of interictal epileptiform activity, absence of preoperative generalized seizures, and absence of seizures in the first postoperative week. A number of factors had no association with outcome (e.g., age at onset, preoperative seizure frequency, and extent of lateral resection). Conclusions: Apparently conflicting results in the literature may be explained by the methodologic issues identified here (e.g., sample size, selection criteria and method of analysis). To obtain a better understanding of patterns of long-term outcome, increased emphasis on longitudinal analytic methods is required. The systematic review of possible risk factors for seizure recurrence provides a basis for planning further research. [source] The structure of perceived qualities of situationsEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 6 2005John A. Edwards Situations can be seen as having attributes or qualities in much the same way as people have traits. The structure of people's perceptions of these situation qualities was explored. A comprehensive list of adjectives that might describe situations was generated, and people rated situations using samples of the words. Across several samples of words and participants and several analytic methods, four factors show up regularly (positivity, negativity, productivity, and ease of negotiation). In a second study, it was shown that these factors predict the way in which people freely sort situations. The conceptual nature of these factors and of situation qualities is discussed, with particular emphasis on how people's goals and perceived outcomes influence their perceptions of situations. Copyright © 2005 John Wiley & Sons, Ltd. [source] A study on a new AVR parameter tuning concept using on-line measured data with the real-time simulatorEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 3 2006Joong-Moon Kim Abstract Automatic voltage regulator (AVR) parameter tuning for voltage control of power system generators has generally been performed with the analytic methods and the simulation methods, which mostly depend on off-line linear mathematical models of power system. However, due to the nonlinear nature of power system, the mathematical models of the excitation system may not be correct. So the excitation control system performances with the parameter set that is tuned by using the mathematical model, may not be appropriate for some operating conditions. This paper presents an AVR parameter tuning method using on-line measured data of the excitation control system with parameter optimization technique. As this method utilizes on-line operating data, it can overcome the limitation of model uncertainty problems of conventional method. To validate the proposed tuning concept, a scaled model excitation system is connected to the real-time power system simulator, and the proposed tuning concept is tested. Copyright © 2006 John Wiley & Sons, Ltd. [source] Theorizing in Family Gerontology: New Opportunities for Research and PracticeFAMILY RELATIONS, Issue 5 2006Karen A. Roberto Abstract: We examine the extent to which theory has been used in empirical studies of families in later life, identify prevalent types of theoretical frameworks, and assess connections between theory and both focal topics and analytic methods in the family gerontology literature. The paper is based on content and methodological analysis of 838 empirical articles with a family-level focus published in 13 social science journals during the 1990s. Approximately one half of the articles included theory, with micro-interpretive (social psychological) theories being used most often to guide and inform research and practice. To advance the field and understand better the intricacies of family life among older adults, we suggest that investigators and practitioners explicitly incorporate theoretical frameworks into their endeavors. [source] Tuvalu and Climate Change: Constructions of Environmental Displacement in The Sydney Morning HeraldGEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 4 2005Carol Farbotko Abstract Tuvalu, a place whose image in the ,West' is as a small island state, insignificant and remote on the world stage, is becoming remarkably prominent in connection with the contemporary issue of climate change-related sea-level rise. My aim in this paper is to advance understanding of the linkages between climate change and island places, by exploring the discursive negotiation of the identity of geographically distant islands and island peoples in the Australian news media. Specifically, I use discourse analytic methods to critically explore how, and to what effects, various representations of the Tuvaluan islands and people in an Australian broadsheet, the Sydney Morning Herald, emphasize difference between Australia and Tuvalu. My hypothesis is that implicating climate change in the identity of people and place can constitute Tuvaluans as .tragic victims. of environmental displacement, marginalizing discourses of adaptation for Tuvaluans and other inhabitants of low-lying islands, and silencing alternative constructions of Tuvaluan identity that could emphasize resilience and resourcefulness. By drawing attention to the problematic ways that island identities are constituted in climate change discourse in the news media, I advocate a more critical approach to the production and consumption of representations of climate change. [source] Identifying the new Keynesian Phillips curveJOURNAL OF APPLIED ECONOMETRICS, Issue 5 2008James M. Nason Phillips curves are central to discussions of inflation dynamics and monetary policy. The hybrid new Keynesian Phillips curve (NKPC) describes how past inflation, expected future inflation, and a measure of real aggregate demand drive the current inflation rate. This paper studies the (potential) weak identification of the NKPC under Generalized Method of Moments and traces this syndrome to a lack of higher-order dynamics in exogenous variables. We employ analytic methods to understand the economics of the NKPC identification problem in the canonical three-equation, new Keynesian model. We revisit the empirical evidence for the USA, the UK, and Canada by constructing tests and confidence intervals based on the Anderson and Rubin (1949) statistic, which is robust to weak identification. We also apply the Guggenberger and Smith (2008) LM test to the underlying NKPC pricing parameters. Both tests yield little evidence of forward-looking inflation dynamics. Copyright © 2008 John Wiley & Sons, Ltd. [source] Holistic trajectories: a study of combined employment, housing and family careers by using multiple-sequence analysisJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES A (STATISTICS IN SOCIETY), Issue 1 2007Gary Pollock Summary., Social science applications of sequence analysis have thus far involved the development of a typology on the basis of an analysis of one or two variables which have had a relatively low number of different states. There is a yet unexplored potential for sequence analysis to be applied to a greater number of variables and thereby a much larger state space. The development of a typology of employment experiences, for example, without reference to data on changes in housing, marital and family status is arguably inadequate. The paper demonstrates the use of sequence analysis in the examination of multivariable combinations of status as they change over time and shows that this method can provide insights that are difficult to achieve through other analytic methods. The data that are examined here provide support to intuitive understandings of clusters of common experiences which are both life course specific and related to socio-economic factors. Housing tenure is found to be of key importance in understanding the holistic trajectories that are examined. This suggests that life course trajectories are sharply differentiated by experience of social housing. [source] Restoration of genetic connectivity among Northern Rockies wolf populationsMOLECULAR ECOLOGY, Issue 20 2010MARK HEBBLEWHITE Probably no conservation genetics issue is currently more controversial than the question of whether grey wolves (Canis lupus) in the Northern Rockies have recovered to genetically effective levels. Following the dispersal-based recolonization of Northwestern Montana from Canada, and reintroductions to Yellowstone and Central Idaho, wolves have vastly exceeded population recovery goals of 300 wolves distributed in at least 10 breeding pairs in each of Wyoming, Idaho and Montana. With >1700 wolves currently, efforts to delist wolves from endangered status have become mired in legal battles over the distinct population segment (DPS) clause of the Endangered Species Act (ESA), and whether subpopulations within the DPS were genetically isolated. An earlier study by vonHoldt et al. (2008) suggested Yellowstone National Park wolves were indeed isolated and was used against delisting in 2008. Since then, wolves were temporarily delisted, and a first controversial hunting season occurred in fall of 2009. Yet, concerns over the genetic recovery of wolves in the Northern Rockies remain, and upcoming District court rulings in the summer of 2010 will probably include consideration of gene flow between subpopulations. In this issue of Molecular Ecology, vonHoldt et al. (2010) conduct the largest analysis of gene flow and population structure of the Northern Rockies wolves to date. Using an impressive sampling design and novel analytic methods, vonHoldt et al. (2010) show substantial levels of gene flow between three identified subpopulations of wolves within the Northern Rockies, clarifying previous analyses and convincingly showing genetic recovery. [source] Joining the Hubble flow: implications for expanding spaceMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2006Luke A. Barnes ABSTRACT The concept of expanding space has come under fire recently as being inadequate and even misleading in describing the motion of test particles in the universe. Previous investigations have suffered from a number of shortcomings, which we seek to correct. We study the motion of test particles in the universe in detail, solving the geodesic equations of General Relativity for a number of cosmological models. In particular, we use analytic methods to examine whether particles removed from the Hubble flow asymptotically rejoin the Hubble flow, a topic that has caused confusion because of differing definitions and invalid reasoning. We conclude that particles in eternally expanding but otherwise arbitrary universes do not in general rejoin the Hubble flow. [source] Masked intervention effects: Analytic methods for addressing low dosage of interventionNEW DIRECTIONS FOR EVALUATION, Issue 110 2006John E. Lochman This chapter describes potential drawbacks of using intent-to-treat (ITT) analyses to examine intervention effects and presents several additional analytic methods as alternatives to ITT. [source] Researcher judgment and study design: Challenges of using administrative dataAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 1 2010Leslie I. Boden PhD Abstract Background Questions have been raised about methods of studies finding substantial undercounting of workplace injuries and illnesses by the Bureau of Labor Statistics (BLS) and workers' compensation agencies. A more recent study of Minnesota concluded that the BLS survey captures 84,90% of workers' compensation cases. Methods We examined the sensitivity of findings in two studies to alternate sample definitions and study assumptions. Results Applying alternate sample construction rules to the earlier study increased estimated BLS reporting rates from 68% to 77%, assuming source independence. Applying alternate assumptions to the more recent Minnesota study reduced its high estimate of BLS reporting from 90% to 53,64%. Conclusions Studies linking administrative data from different sources require substantial judgment in constructing research datasets and choosing analytic methods. Moreover, different sample construction rules lead to different results. This suggests that sensitivity analysis should be carried out when alternatives cannot be ruled out. In this case, sensitivity analysis supports the hypothesis of substantial underreporting. Am. J. Ind. Med. 53:37,41, 2010. © 2009 Wiley-Liss, Inc. [source] What's in a Sector?PUBLIC ADMINISTRATION REVIEW, Issue 6 2003The Shifting Career Plans of Public Policy Students Recent decades have seen a trend in which public policy graduates shun government and enter private-sector employment. In part, the shift reflects changing sectoral opportunities, but its magnitude and consistency are puzzling,even troubling,in light of the need for public-sector talent. Data from a two-year series of surveys and interviews with policy students reveal that many begin their training with uncertain career goals and ambivalence about public-sector work. Interest in government declines from entry to graduation, and it appears that the policy curriculum,heavy on analytic methods and conveying cautions about policy making,does little to promote a public-sector orientation. Those planning to enter government are strongly motivated by a desire to have an impact, whereas those drawn to the private sector seek financial resources and professional development. Many anticipate fluid careers and choose positions expected to offer growth, a feature more commonly associated with private than public jobs. [source] The validity of analyses testing the etiology of comorbidity between two disorders: a review of family studiesTHE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 4 2003Soo Hyun Rhee Background:, Knowledge regarding the causes of comorbidity between two disorders has a significant impact on research regarding the classification, treatment, and etiology of the disorders. Two main analytic methods have been used to test alternative explanations for the causes of comorbidity in family studies: biometric model fitting and family prevalence analyses. Unfortunately, the conclusions of family studies using these two methods have been conflicting. In the present study, we examined the validity of family prevalence analyses in testing alternative comorbidity models. Method:, We reviewed 42 family studies that used family prevalence analyses to test three comorbidity models: the alternate forms model, the correlated liabilities model, or the three independent disorders model. We conducted the analyses used in these studies on datasets simulated under the assumptions of 13 alternative comorbidity models including the three models tested most often in the literature. Results:, Results suggest that some analyses may be valid tests of the alternate forms model (i.e., two disorders are alternate manifestations of a single liability), but that none of the analyses are valid tests of the correlated liabilities model (i.e., a significant correlation between the risk factors for the two disorders) or the three independent disorders model (i.e., the comorbid disorder is a third, independent disorder). Conclusion:, Family studies using family prevalence analyses may have made incorrect conclusions regarding the etiology of comorbidity between disorders. [source] ROUTES TO HIGHER-ORDER ACCURACY IN PARAMETRIC INFERENCEAUSTRALIAN & NEW ZEALAND JOURNAL OF STATISTICS, Issue 2 2009G. Alastair Young Summary Developments in the theory of frequentist parametric inference in recent decades have been driven largely by the desire to achieve higher-order accuracy, in particular distributional approximations that improve on first-order asymptotic theory by one or two orders of magnitude. At the same time, much methodology is specifically designed to respect key principles of parametric inference, in particular conditionality principles. Two main routes to higher-order accuracy have emerged: analytic methods based on ,small-sample asymptotics', and simulation, or ,bootstrap', approaches. It is argued here that, of these, the simulation methodology provides a simple and effective approach, which nevertheless retains finer inferential components of theory. The paper seeks to track likely developments of parametric inference, in an era dominated by the emergence of methodological problems involving complex dependences and/or high-dimensional parameters that typically exceed available data sample sizes. [source] Increase in saliva cotinine after three hours' exposure to second-hand smoke in barsAUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 3 2005Alistair Woodward Objective: To determine whether measurement of cotinine in saliva is a sensitive measure of exposure to secondhand smoke (SHS) among customers in bars. Design: Before/after comparison of saliva cotinine and subjective assessments of SHS. Setting: Three bars in Wellington, New Zealand, June 2003. Participants: Eleven non-smoking medical students spent three hours in each location. They provided saliva samples before and after the visit, counted numbers of lit cigarettes in each bar, and assessed the smokiness of the venue. Samples were tested for cotinine using liquid chromatography coupled with mass spectrometry. Results: Cotinine levels post-visit were consistently higher than baseline. The mean difference was 1.03 ng/mL with a 95% confidence interval of 0.76,1.30 ng/mL. Adjustments to post-visit levels for metabolism and clearance of cotinine made very little difference to these results. Males tended to have higher baseline levels than females, and to show smaller increases. The bar with the greatest increase in cotinine was judged to be the smokiest on the basis of averaged cigarette counts and scores for presence of smoke and odour. Conclusion: The cotinine in saliva, when tested with the analytic methods described here, provides a means of assessing relatively short-term exposures to SHS. [source] Statistical methods for longitudinal research on bipolar disordersBIPOLAR DISORDERS, Issue 3 2003John Hennen Objectives: Outcomes research in bipolar disorders, because of complex clinical variation over-time, offers demanding research design and statistical challenges. Longitudinal studies involving relatively large samples, with outcome measures obtained repeatedly over-time, are required. In this report, statistical methods appropriate for such research are reviewed. Methods: Analytic methods appropriate for repeated measures data include: (i) endpoint analysis; (ii) endpoint analysis with last observation carried forward; (iii) summary statistic methods yielding one summary measure per subject; (iv) random effects and generalized estimating equation (GEE) regression modeling methods; and (v) time-to-event survival analyses. Results: Use and limitations of these several methods are illustrated within a randomly selected (33%) subset of data obtained in two recently completed randomized, double blind studies on acute mania. Outcome measures obtained repeatedly over 3 or 4 weeks of blinded treatment in active drug and placebo sub-groups included change-from-baseline Young Mania Rating Scale (YMRS) scores (continuous measure) and achievement of a clinical response criterion (50% YMRS reduction). Four of the methods reviewed are especially suitable for use with these repeated measures data: (i) the summary statistic method; (ii) random/mixed effects modeling; (iii) GEE regression modeling; and (iv) survival analysis. Conclusions: Outcome studies in bipolar illness ideally should be longitudinal in orientation, obtain outcomes data frequently over extended times, and employ large study samples. Missing data problems can be expected, and data analytic methods must accommodate missingness. [source] Water Resource Development in the Quaternary Ryukyu Limestone Regions of Japan: Application of the GIS to the Site Selection of Underground DamsACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2001Kaijun JIANG Abstract Based on the natural and social conditions as well as hydrogeological characteristics of the Ryukyu limestone, a major aquifer in the Ryukyu Islands, a conception of underground dam, was proposed in the early 1970s in order to develop ground water resources in the Quaternary Ryukyu limestone regions of Japan. The practice of nearly thirty years has shown that the underground dam is an environment-friendly and effective way for developing ground water in these regions. To further improve the technology associated with underground dam, the authors introduced related analytic methods. The application of the geographical information system technology to site selection of the underground dam is reported in this paper. [source] Applications of Taxometric Methods to Problems of Comorbidity: Perspectives and ChallengesCLINICAL PSYCHOLOGY: SCIENCE AND PRACTICE, Issue 4 2001Irwin D. Waldman We share Meehl's view that taxometric procedures hold considerable promise for elucidating questions regarding psychiatric comorbidity. Drawing on examples from the domain of childhood disruptive disorders, we discuss why the issues raised by Meehl are scientifically and pragmatically important and outline several profitable applications of taxometric methods to questions of comorbidity (e.g., estimating the statistical relations between latent taxa). We explain why taxometric methods and other sophisticated latent variable methods are needed to answer such questions and provide examples of how certain statistical methods have been used to make erroneous inferences regarding taxonicity. Several important unresolved issues bearing on the use of taxometric procedures and their application to questions of comorbidity are delineated, including (a) the distributional assumptions of taxometric methods, (b) the construct validation of provisional taxa identified by taxometric analyses, (c) the relation of taxometric methods to other latent variable techniques (e.g., latent class analysis), (d) the potential existence of spurious taxa, (e) the question of "fuzzy taxonicity," and (f) "configural taxa." We conclude with a discussion of analytic methods for characterizing and understanding the covariation between latent dimensions as opposed to taxa. [source] | |||||||||||||||||||||||||