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PubMed1995

Soar and the case for unified theories of cognition.

Despite the potential importance to cognitive psychology of unified theories no attempt has been made to assess concretely the methodological problems that such theorising produces. This paper addresses this issue of unified theorising, and in particular the arguments for unified theories put forward by Newell (1990). Close examination of these arguments reveals that Newell's approach does not adequately counter the difficulties which beset the grand theories of the 1930s, nor the problems of irrelevant specification which arise in modern computational psychological work. These difficulties do not prevent the development of unified theories, but they do pose serious problems, problems which it is argued can only be met by rigorous empirical testing together with extreme methodological sensitivity. The methodological concerns lead us to examine Soar, perhaps the most well-developed unified theory, from methodological, computational, and empirical perspectives. Our conclusions are that, whilst Soar represents an impressive body of research, its methodological foundations are insecure, it is ill specified as a computational/psychological theory, and under empirical testing it does not stand up to close scrutiny as a unified theory. The Soar research programme as it currently stands thus fails to meet the necessary methodological demands imposed by unified theorising.

Cognition↗
PubMed1986

A methodologic assessment of studies comparing magnetic resonance imaging and computed tomography of the brain.

To evaluate the methods used in studies comparing magnetic resonance imaging (MRI) and computed tomography (CT) of the brain, we reviewed English language articles published between 1981 and early 1986. Of 83 studies comparing the accuracy of MRI and CT in 10 or more patients, few met methodologic standards for evaluations of the efficacy of new diagnostic tests. Limitations were found in how study populations were assembled, in test performance and interpretation, and in analysis of study findings. Greater attention to design and execution of comparison studies could overcome these limitations and help demonstrate MRI's true diagnostic value.

Brain↗
PubMed1999

The development of computer-generated tailored interventions.

Tailoring information to individual characteristics of a person is a promising line of development of self-help interventions. This article presents a three-phase methodology for developing computer-generated tailored interventions. The first phase of the development concerns the formulation of intervention objectives on the basis of analyses of the cognitive determinants of behavior. The second phase concerns the core of the development of a tailored intervention. For each objective, a so-called tailoring matrix is developed which specifies the individual characteristics to which the message will be adapted to. The tailoring matrices are the basis of the tailored messages and the tailoring questionnaire which will assess the individual characteristics. In the third phase, all the separately written messages must be integrated to one coherent intervention text and the lay-out is designed. This methodology may result in largely different tailored interventions depending on the theoretical framework used, the adaptation of the messages and the inclusion of feedback.

Cognition↗
PubMed1985

Present and future developments of stereotactic technology.

Incorporation of a surgical computer system into stereotactic methodology provides the facility for efficient utilization of the multiple data bases at the disposal of the modern stereotactician. Computed tomography, magnetic resonance imaging, and digital fluoroscopy data gathered in stereotactic conditions are digitized into a stereotactic surgical matrix for surgical planning and interactive surgical procedures. The advantages of this system are illustrated in stereotactic biopsy, interstitial irradiation, and laser resections of intracranial tumors.

Biopsy↗
PubMed2006

Stepwise methodology for plain radiographic assessment of pedicle screw placement: a comparison with computed tomography.

OBJECTIVE: The objective of this study is to evaluate the effectiveness of a specific methodology for plain radiographic assessment of lumbar pedicle screw position. PURPOSE: To evaluate the effectiveness of using orthogonal plain radiographs and a systematic method of interpretation, developed by the senior author, in assessing the placement of lumbar and lumbosacral pedicle screws. STUDY DESIGN: This was an adult cadaver study of the accuracy of using plain radiographs or computed tomography to assess pedicle screw position. Plain radiographs were performed and compared with computed tomography (CT) scans. Gross anatomic dissections were performed to directly confirm screw position. Variables, including screw material, radiographic view, and screw dimensions, were assessed for their effect on the ability of physicians to determine pedicle screw position. Multiple readers were included in the study, including 1 spine Fellow, 3 experienced orthopedic spine surgeons, and 1 neuroradiologist. METHODS: Five adult cadaveric spines were instrumented with titanium pedicle screws from L1 to S1. Screws were placed outside the confines of the pedicle in all 4 quadrants or within the pedicle using a Latin-Square design. Each cadaver was imaged with orthogonal radiographs and high-resolution CT scans. The spines were then reimaged after the instrumentation was replaced with stainless steel screws placed in the identical position. Finally, each spine was dissected to assess the exact position of the screws. Images were read in a blinded fashion by 1 spine fellow, 2 staff surgeons, and a staff radiologist. The results were compared with the known screw positions at dissection. RESULTS: In total, 120 pedicle screws were placed, 44 (38%) outside the confines of the pedicle. Sensitivity, defined as the percent of the misplaced screws that were correctly identified, was similar across the 3 diagnostic tests, but markedly improved when all CT formats were considered together. Similarly, specificity, defined as the percent of screws correctly read as being placed within the pedicle, was independent of radiographic examination. Sensitivity of the radiographic technique was 70.1% and specificity was 83.0%, whereas sensitivity for CT scans was 84.7% and specificity was 89.7%. There was an observed association with anatomic level, with a consistently less accuracy in detecting screw position at L1 with plain x-ray (P=0.001). Additionally, correct position of stainless steel screws was more difficult to detect as compared with titanium (P=0.033) using either x-rays or CT. Other variables examined, such as screw length and screw diameter, did not have an effect on the ability to read the positioning. CONCLUSIONS: CT scans, often considered the "gold standard" for clinical assessment of pedicle screw placement, have limitations when validated with gross anatomical dissection. The described systematic method for evaluating pedicle screw placement using orthogonal plain radiographs attained accuracy comparable to high-resolution CT scans.

Adult↗
PubMed1990

Computer analyses of EEG-sleep in the neonate: methodological considerations.

Neonatal EEG interpretation can aid in the estimation of central nervous system maturation, as well as provide diagnostic and prognostic information of the high-risk infant. However, one cannot easily visualize the complex interrelationships coupling EEG and polysomnographic components of the EEG-sleep rhythm. This is particularly relevant for the preterm neonate, in whom a rudimentary sleep cycle has not yet been clearly delineated. Computer analysis can augment the information derived from the visual interpretation of scalp-generated EEG activity. Automated techniques for EEG-sleep analysis have only recently been applied to a neonatal population. Such studies have been limited to full-term rather than preterm infants and rely on conventional methods that assume stationarity of neurophysiologic signals. We describe a computer system that simultaneously compares behavioral and electrographic components of EEG-sleep in a manner that preserves the integrity of the signals over time, while investigating the time- and frequency-dependent relationships among signals. Strategies for on-line and off-line editing, data storage, and off-line signal processing are described. Computational algorithms regarding analyses of EEG power, motility, and cardiorespiratory data are being used to study the ontogeny of EEG-sleep in asymptomatic preterm and full-term neonates. Computer strategies are based on both principles of stationarity and nonstationarity of physiologic signals and are applied depending on the temporal resolution required for specific signal processing needs.

Computer Systems↗
PubMed2005

Methodology is more than research design and technology.

The Society for Computers in Psychology has been at the forefront of disseminating information about advances in computer technology and their applications for psychologists. Although technological advances, as well as clean research designs, are key contributors to progress in psychological research, the justification of methodological rules for interpreting data and making theory choices is at least as important. Historically, methodological beliefs and practices have been justified through intuition and logic, an approach known as foundationism. However, naturalism, a modern approach in the philosophy of science inspired by the work of Thomas S. Kuhn, indicates that all aspects of scientific practice, including its methodology, should be evaluated empirically. This article examines implications of the naturalistic approach for psychological research methods in general and for the current debate that is often framed as one of qualitative versus quantitative methods.

Computers↗
PubMed1987

Demographic heterogeneity and uncertainty in population projections.

Recent developments in a class of stochastic population processes were used to study the impact of demographic heterogeneity on the uncertainty of population projections. Selected for study by computer simulation were population projections for East Africa designed to quantify opinions regarding expected fertility and mortality declines. Since both fertility and mortality declined in these projections, their laws of evolution may be described as time inhomogeneous. The computer simulation studies reported in this paper strongly suggest that randomized laws of evolution should be taken into account in further developments of population projection methodologies designed formally and computationally to accommodate uncertainty. Variability in fecundability, the kind of demographic heterogeneity studied in this paper, is only one aspect of these randomized laws.

Africa, Eastern↗
PubMed1993

The delay before onset of accelerated tumour cell repopulation during radiotherapy: a direct maximum-likelihood analysis of a collection of worldwide tumour-control data.

The worldwide collection of control data for head and neck tumours presented by Withers et al. (Withers, H.R., Taylor, J.M.G. and Maciejewski, B. Acta Oncol. 27: 131-146, 1988) was reanalysed using a model which includes an explicit lag phase before the onset of tumour clonogen repopulation. A direct maximum-likelihood approach was used and the methodology extended to include the computation of profile-likelihood confidence limits. A statistically significant (p = 0.02) lag of 29 days was obtained with 95% confidence limits covering the range 17-31 days. However, the confidence interval was disconnected, and excluded the period 21-23 days. The analysis gave a time factor of 0.66 Gy/day. The mean values confirm the conclusions drawn by the original authors using a two-stage (indirect) method, and the values are similar to those calculated here for another data set comprising 496 patients (lag period = 26 (19-33) days). However, the data set itself is retrospective, and potentially subject to a number of biases. Therefore any clinical conclusions can only be tentative. A new feature of the methodology is the computation of profile-likelihood confidence limits and this will be useful in future direct analyses of clinical data of this type. The more usually computed normal approximation to the confidence limits have been shown to be inadequate in this analysis, and either profile-likelihood limits or likelihood ratio tests must be employed to determine the significance of the model parameters.

Head and Neck Neoplasms↗
PubMed2006

Response surface optimization for joint contact model evaluation.

When optimization is used to evaluate a joint contact model's ability to reproduce experimental measurements, the high computational cost of repeated contact analysis can be a limiting factor. This paper presents a computationally-efficient response surface optimization methodology to address this limitation. Quadratic response surfaces were fit to contact quantities (contact force, maximum pressure, average pressure, and contact area) predicted by a discrete element contact model of the tibiofemoral joint for various combinations of material modulus and relative bone pose (i.e., position and orientation). The response surfaces were then used as surrogates for costly contact analyses in optimizations that minimized differences between measured and predicted contact quantities. The methodology was evaluated theoretically using six sets of synthetic (i.e., computer-generated) contact data, and practically using one set of experimental contact data. For the synthetic cases, the response surface optimizations recovered all contact quantities to within 3.4% error. For the experimental case, they matched all contact quantities to within 6.3% error except for maximum contact pressure, which was in error by up to 50%. Response surface optimization provides rapid evaluation of joint contact models within a limited range of relative bone poses and can help identify potential weaknesses in contact model formulation and/or experimental data quality.

Bone Screws↗
PubMed2006

Generating psychotropic drug exposure data from computer-based medical records.

PURPOSE: To develop a methodology for extracting psychotropic drug exposure data from computer-based medical records and for generating drug exposure variables suitable for secondary use. METHODS: In South-Verona, Italy, a registry including every patient receiving psychotropic medications is operating since 2004. The basic structure of the registry is the medication record. Each record stores data on a specific prescription, and patients with more than one prescription have more than one record. RESULTS: The longitudinal history of drug use was described identifying consecutive prescriptions of a specific drug, concomitant prescriptions of a specific drug and distinct prescriptions of a specific drug. Consecutive prescriptions implies that the beginning of the second prescription coincides with the end of the first prescription, concomitant prescriptions implies that the beginning of the second prescription precedes the end of the first prescription, distinct prescriptions implies that a gap of at least 1 day exists between prescriptions. Using this framework of drug representation, we identified episodes of drug therapy, where each episode is constituted of consecutive and/or concomitant prescriptions. Within each episode, prescriptions were categorised into theoretical phases, where the beginning of the new phase always coincides with the end of the previous phase. On the basis of this data representation, a module operating in Access and using Visual Basic for Applications was developed for creating episodes and phases on a routine basis (available from authors). A graphical representation of this conceptual model is presented. CONCLUSION: The development of a simple methodology for extracting and generating drug exposure data suitable for secondary use will allow a better understanding of the beneficial and adverse consequences of psychotropic drug use in ordinary practice.

Drug Prescriptions↗
PubMed1983

Computerized nutrient data bases: II. Development of model for appraisal of nutrient data base system capabilities.

A review model has been developed that present a methodology for assessing the computational accuracy of a computerized dietary analysis system and provides a strategy for examining the status of nutrient data utilized in the computations. The model, which consists of a questionnaire, five computing tasks, and an interpretation guide, was tested by seven nutrient data base systems and was found to be a capable tool for assessing their capabilities and accuracy. The review model is intended to be a prototype that can be modified for special needs. Developers of nutrient data base systems are encouraged to utilize this systematic methodology to review their data bases and the performance of their computer programs.

Computers↗
PubMed1993

Identification of patients with impaired hepatic drug metabolism using a limited sampling procedure for estimation of phenazone (antipyrine) pharmacokinetic parameters.

Phenazone (antipyrine) 1g was given by short intravenous infusion to 62 study participants (10 healthy drug-free volunteers and 52 patients with chronic liver disease). A Bayesian approach was developed to determine the individual pharmacokinetic parameters of phenazone. Statistical characteristics of the population pharmacokinetic parameters were first evaluated for 30 patients. When combined with 1 plasma drug concentration from members of the second group, these led to a Bayesian estimation of individual pharmacokinetic parameters for the remaining 32 individuals. Total clearance computed by Bayesian estimation was compared with maximal likelihood estimation of this parameter, the classical procedure. No statistically significant differences were found. Performance of the developed methodology was evaluated by computing bias and precision. The mean error was 0.0477 L/h. The precision of the prediction of this parameter (0.155 L/h) remained lower than the interindividual standard deviation (0.765 L/h). This procedure enables the estimation of individual pharmacokinetic parameters for phenazone. In this study, numerous laboratory tests were performed. A highly significant correlation (p < 0.001) was found between phenazone clearance and the prothrombin time, albumin, gamma-globulin, factor V, antithrombin III, fibrinogen and total bilirubin. Discriminant analysis determined that protein, alkaline phosphatase, creatininaemia and gamma-globulin had more significant discriminating power and gave better prognostic results than those seen with the Child-Pugh test.

Adult↗
PubMed1995

Cognitive computer-based video analysis: its application in assessing the usability of medical systems.

This paper describes a methodology, based on cognitive research, for assessing the usability of medical computing systems. The issue of developing appropriate evaluation tools, both for use in the design process and for analysis of end products, is beginning to be recognized as being of great importance. In this paper, the use of video recording for collecting empirical data on system usability is detailed. The techniques described allow for the collection of an integrated data set consisting of the transcripts of physicians as they "think aloud" in interacting with a medical system, along with video records of user-computer interaction. The use of coding methodologies and a computer-based annotation system for the analysis of video data are described. Our preliminary experience indicates that this methodology offers a powerful way for assessing physicians' informational needs. Implications for the development and evaluation of medical information systems are discussed.

Computer Systems↗
PubMedDate not supplied

An informatics approach to complex research problems. Dynamic process modeling.

In the nursing literature, the term computer simulation refers exclusively to an educational tool that requires the user to respond to simulated events and to engage in the decision-making process. However, computer simulations are frequently constructed to model dynamic systems (systems that change with time) and to randomly simulate real life events in an effort to study complex problems. In this context, computer simulation is a research methodology and is used in a wide variety of disciplines including the behavioral sciences and business management. Nurses will inevitably encounter research studies where computer simulation has been employed. It is also very likely that this methodology will be used as a nursing research tool in the near future. This article introduces and describes the use of computers to model dynamic systems, the theory that supports simulation modeling as a research methodology, and the issues of model validation. Included are examples of four different research problems from diverse fields of study where computer simulation has been applied.

Computer Simulation↗
PubMed1987

Deformation analyses in cell and developmental biology. Part I--Formal methodology.

This study presents a computational approach for the deformation analyses of problems in cell and developmental biology. Cells and embryos are viewed mechanically as axisymmetric shell-like bodies containing a body of incompressible material. The analysis approach is based on the finite element method. It is comprised of three finite element ingredients: an axisymmetric shell/membrane element valid for modeling finite bending, shearing and stretching; a volume constraint algorithm for modeling the membrane-bound incompressible material; and a contact algorithm for modeling the mechanical interactions between deformable bodies. Part II of this study will demonstrate how these three ingredients can be applied to analyze mechanical experiments on cells. This same method is also useful for simulating embryonic shape changes during development.

Algorithms↗
PubMed1988

Computer aided photograph analyses in oral medicine--a pilot study.

In this methodological, pilot study the usefulness of computer aided photograph analyses (CAPA) was tested for the demonstration of intraoral tissue changes, registered by standardized, clinical close-up (2:1) photography. Individual effects of tobacco on, a.o., the blood vessel supply of the oral mucosa were, thus, documented photographically every five minutes after cigarette smoking and snuff-dipping respectively in three healthy volunteers, aged 45, 35 and 30 years. In the same way the effects of nicotine, released from a 4mg Nicorette chewing gum (Leo), were recorded in all test persons. The clinical photographs were transformed into digital images and analysed by means of computer graphics (Supernova 24.1 and IBM-AT; ART 2 programme) for comparative investigations of the series of pictures. The methods employed facilitated the demonstration of even minor tissue changes in the original photographs. Standardized macrophotography of the oral mucosa and subsequent CAPA-procedures may be valuable tools in interdisciplinary research with the purpose to visualize, a.o. drug-induced, vascular changes. The digitized images may be used for statistical analyses. Further improvements of the CAPA-technique are in progress.

Adult↗
PubMed2004

A Bayesian analysis of the 4-year follow-up data of the Wisconsin epidemiologic study of diabetic retinopathy.

The Wisconsin epidemiologic study of diabetic retinopathy (WESDR) is a population-based epidemiologic study carried out in Southern Wisconsin during the 1980s of the last century. The resulting data were analysed by different statisticians and ophthalmologists during the last two decades. Most of the analyses were carried out on the baseline data, although there were two follow-up studies on the same population. In this present paper, we provide a Bayesian analysis of the first follow-up data which were taken 4 years after the baseline study. Our Bayesian analysis provides estimates of the associated covariate effects. Choice of the best model in terms of the covariate inclusion is also performed. The baseline data were used to set the prior for the parameters. Extensive numerical computations illustrate our present methodology.

Bayes Theorem↗