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PubMed2001

A framework for food-based dietary guidelines in the European Union.

UNLABELLED: The nutrient targets derived from analysis of the relation between nutrient intake and disease prevalence or other scientific evidence, have to be translated into food-based guidelines in order to be understood by the general population. Furthermore, Food-Based Dietary Guidelines (FBGD) have to be realistic, attainable and culturally acceptable and should also give consideration to relevant social, economic, agricultural and environmental factors affecting food availability and eating patterns. This requires a thorough understanding of the relation between foods, food patterns and nutrient intakes in the population. The aims of Working Party 2 were to propose a framework for strategies in the development of FBDG and to examine existing data for nutrient and food intakes in the EU. METHODS: The over-all strategy given by the joint FAO/WHO consultation 1995 was used as the starting point, i.e. target foods or food patterns for public health nutrition programmes should be identified from an analysis of prevailing food and nutrient intakes. Prevailing data for food and nutrient intakes in 14 EU countries were examined and different principles and options for the derivation of FBDG were explored. Methodological issues and their influence on the interpretation of data for the development of FBDG were also examined. RESULTS: The process from nutrients to foods can be briefly: 1) identification of major food sources of the nutrient of interest, 2) identification of foods contributing substantially to population intakes, 3) identification of foods or food patterns compatible with desirable nutrient intakes or explaining variations in nutrient intakes, 4) formulation of FBDG into foods, portion sizes, frequency of intake, meal composition taking attainability and acceptability as well as compatibility of co-existing guidelines into account. The level of complexity that can be applied in the analytical approaches depends on the characteristics of available intake data. A detailed analysis requires data on an individual level for nutrients, foods, food patterns, eating and meal habits etc. When individual data are available different analytical approaches (examination of distribution of intakes, correlation analysis between foods and nutrients, examination of food intakes in compliers/non-compliers to nutrient goals, discriminant analysis, cluster/factor analysis) can be used to identify key foods or food patterns fulfilling nutrient goals. The examination of prevailing food and nutrient intake data in the EU revealed: a number of methodological differences in approaches to dietary surveys exist in the EU countries e.g., regarding methods used, selection of population, classification of foods, which have to be kept in mind in pan-EU comparisons at present there is a substantial gap between actual intakes and present nutrient goals suggesting that major changes of dietary habits are needed while some food patterns were consistently related to intake of specific nutrients in most EU countries, other patterns showed large variations between countries methodological issues, such as survey duration, survey techniques, under- or over-reporting, could have substantial influence on the identification of target foods or food patterns. CONCLUSIONS: A science-based analysis of nutrient and food intakes allows development of FBDG, which, if implemented, are likely to result in mean population intakes closer to nutrient goals. Acknowledging the social and cultural differences within the EU as well as the need to focus on the most relevant public health problem in the population, FBDG should first be developed within member states. Harmonisation of survey methods within the EU would facilitate development of regional and EU FBDG.

Cluster Analysis↗
PubMed1998

Analytical and simulation results for stochastic Fitzhugh-Nagumo neurons and neural networks.

An analytical approach is presented for determining the response of a neuron or of the activity in a network of connected neurons, represented by systems of nonlinear ordinary stochastic differential equations--the Fitzhugh-Nagumo system with Gaussian white noise current. For a single neuron, five equations hold for the first- and second-order central moments of the voltage and recovery variables. From this system we obtain, under certain assumptions, five differential equations for the means, variances, and covariance of the two components. One may use these quantities to estimate the probability that a neuron is emitting an action potential at any given time. The differential equations are solved by numerical methods. We also perform simulations on the stochastic Fitzugh-Nagumo system and compare the results with those obtained from the differential equations for both sustained and intermittent deterministic current inputs with superimposed noise. For intermittent currents, which mimic synaptic input, the agreement between the analytical and simulation results for the moments is excellent. For sustained input, the analytical approximations perform well for small noise as there is excellent agreement for the moments. In addition, the probability that a neuron is spiking as obtained from the empirical distribution of the potential in the simulations gives a result almost identical to that obtained using the analytical approach. However, when there is sustained large-amplitude noise, the analytical method is only accurate for short time intervals. Using the simulation method, we study the distribution of the interspike interval directly from simulated sample paths. We confirm that noise extends the range of input currents over which (nonperiodic) spike trains may exist and investigate the dependence of such firing on the magnitude of the mean input current and the noise amplitude. For networks we find the differential equations for the means, variances, and covariances of the voltage and recovery variables and show how solving them leads to an expression for the probability that a given neuron, or given set of neurons, is firing at time t. Using such expressions one may implement dynamical rules for changing synaptic strengths directly without sampling. The present analytical method applies equally well to temporally nonhomogeneous input currents and is expected to be useful for computational studies of information processing in various nervous system centers.

Action Potentials↗
PubMed2005

An economic evaluation of universal infant vaccination strategies against hepatitis B in Thailand: an analytic decision approach to cost-effectiveness.

To evaluate the cost-effectiveness of four infant vaccination strategies aimed at protecting the Thai population against hepatitis B virus (HBV) infection, vaccination and giving hepatitis B immunoglobulin (HBIg) to high-risk infants were compared with universal vaccination of infants and no vaccination. An analytic decision model was used to estimate the clinical and economic consequences of HBV for a hypothetical cohort of newborns for each of the immunization strategies. The model focused on the numbers and the costs of cases prevented. The decision model examined four different HBV management strategies: 1. screening for HBsAg, and vaccination; 2. screening for HBsAg, then HBeAg, and vaccination; 3. universal vaccination of all neonates; and 4. no vaccination. The cost-effectiveness per case prevented for Strategy 1 was 292.79 baht; for Strategy 2, 264.34 baht; for Strategy 3, 151.05 baht; and for Strategy 4, 0 baht. The incremental cost comparing Strategy 3 to Strategy 4 was 6,521 baht; comparing Strategy 2 to Strategy 3, 20,000 baht; and comparing Strategy 1 to Strategy 2, 95,000 baht. There is no socially acceptable threshold value for cost per case prevented to guide decisions on funding health care interventions. Strategy 3 should certainly be continued. Nevertheless, based on these results, Strategy 2 may be considered, despite the incremental cost being about 2 times that of Strategy 3, as it might represent a worthwhile investment of public funds.

Cost-Benefit Analysis↗
PubMed1998

People and eyes: statistical approaches in ophthalmology.

In conclusion, when an observation by its nature involves two eyes, as for blindness, statistical analyses should be conducted on individuals rather than eyes and between eye correlation is not a problem. In other circumstances, if information on only one eye per individual is used in the analysis there is a potential "waste" of information leading to less precise estimates of effect and less power. In addition, bias may be introduced into a study if there is non-random selection of the eye for inclusion in the analysis. The use of an overall summary of ocular findings for an individual may result in "wastage" of information in a similar fashion to the use of only one eye per individual. On the other hand, an analysis of individual eyes with no allowance made for between eye correlation may result in falsely narrow confidence intervals around estimates of effect. Between eyes correlation may be assessed empirically using the kappa statistic or similar means. If between eye correlation is substantial, statistical techniques exist which can utilise all available data while allowing for the correlation. In some circumstances a powerful design may be to use the fellow eye as a "control". Two conclusions may be drawn from this review of analytical approaches to the analysis of clinical data in the BJO. Firstly, the analytical approaches employed in many studies fail to use all the data available. In other words the analysis is less than "optimal". Secondly, in a proportion of studies, inappropriate statistical methods are used which may lead the investigator to draw inappropriate conclusions. In other words, the analysis is invalid. Ophthalmic data, by their very nature, present particular statistical challenges. We emphasise the need to involve appropriate statistical expertise in the design and analysis of ophthalmic studies.

Bias↗
PubMed2002

Analytic considerations for measuring environmental chemicals in breast milk.

The presence of environmental chemicals in human breast milk is of general concern because of the potential health consequence of these chemicals to the breast-fed infant and the mother. In addition to the mother's exposure, several features determine the presence of environmental chemicals in breast milk and their ability to be determined analytically. These include maternal factors and properties of the environmental chemical--both physical and chemical--such as its lipid solubility, degree of ionization, and molecular weight. Environmental chemicals with high lipid solubility are likely to be found in breast milk; they include polyhalogenated compounds such as polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, organochlorine insecticides, and polybrominated diphenylethers. These fat-soluble chemicals are incorporated into the milk as it is synthesized, and they must be measured in accordance with the fat content of the milk to allow for meaningful comparisons within an individual and among populations. Although the analytic approach selected to measure the environmental chemical is predominantly determined by the characteristics of the chemical, the concentration of the chemical in the milk sample and the existence of structurally similar chemicals (e.g., congeners) must be considered as well. In general, the analytic approach for measuring environmental chemicals in breast milk is similar to the approach for measuring the same chemicals in other matrices, except special considerations must be given for the relatively high fat content of milk. The continued efforts of environmental scientists to measure environmental chemicals in breast milk is important for defining the true contribution of these chemicals to public health, especially to the health of the newborn. Work is needed for identifying and quantifying additional environmental chemicals in breast milk from the general population and for developing analytic methods that have increased sensitivity and the ability to speciate various chemicals.

Adult↗
PubMed1996

Investigation of the impact of pharmacokinetic variability and uncertainty on risks predicted with a pharmacokinetic model for chloroform.

A sensitivity and uncertainty analysis was performed on the Reitz et al. (Toxicol. Appl. Pharmacol., 1990: 105, 443) physiologically based pharmacokinetic (PBPK) risk assessment model for chloroform. The analytical approach attempted to separately consider the impacts of interindividual variability and parameter uncertainty on the predicted values of the dose metrics in the model, as well as on liver cancer risk estimates obtained with the model. An important feature of the analytical approach was that an attempt was made to incorporate information on correlation between important parameters, for example, the observed correlation between total blood flow and alveolar ventilation rate. Using the published PBPK model for chloroform, the best estimate of the average population risk based on the preferred pharmacodynamic dose metric (PTDEAD), representing cell death, is 9.2 x 10(-7); this estimate is more than 500-fold lower than the risk estimate of 5.3 x 10(-4) based on an alternative pharmacokinetic dose metric (AVEMMB), which represents tissue adduct formation. However, when interindividual variability was considered the range of individual risks (from the 5th to the 95th percentile of the population) predicted with PTDEAD was extremely broad (from 3.0 x 10(-13) to 3.2 x 10(-4)), while individual risks predicted with AVEMMB only varied over a factor of four (from 1.9 x 10(-4) to 7.4 x 10(-4)). As a result, the upper 95th percentile of the distribution of individual risk estimates based on the preferred cell death metric were within a factor of three of the 95th percentile for the pharmacokinetic alternative. The crucial factor with respect to the much greater variability of chloroform risk estimates based on cell death is that the dose metric, PTDEAD, is exquisitely sensitive to variation of the parameters in the model defining the response of cells to the cytotoxicity of chloroform. Unfortunately, these key parameters are also highly uncertain, as well as strongly correlated. As a result it proved impossible to accurately quantify the additional impact of parameter uncertainty on the dose metrics and risk estimates for chloroform. In general, however, the approach used in this study should be useful for differentiating the impact of interindividual variability and parameter uncertainty on PBPK-based risk assessments of other chemicals where the sensitivity, uncertainty, and correlation of the key parameters are more limited.

Animals↗
PubMed2003

Current status of the evaluation of information retrieval.

This is the second in the series of the articles on an application of the systems analytic approach to evaluation of information retrieval (IR). In the previous article a historical overview of IR was presented and existing terminological problems associated with IR were identified and discussed. In the presented article the current status of IR evaluation is summarized, and different evaluation approaches are discussed. The Cranfield evaluation model and the most often used relevance-based measures of recall and precision are explained, and their problems are presented. Possible evaluation alternatives to the Cranfield model are discussed, and the case for a systems analytic approach to IR is summarized.

Abstracting and Indexing↗
PubMed2003

Interspecific variation in terpenoid composition of defensive secretions of European Reticulitermes termites.

Sixteen terpene compounds were isolated from the soldier defensive secretions of seven European termite taxa of the genus Reticulitermes (Isoptera, Rhinotermitidae). We describe species-specific mixtures of monoterpenes (alpha-pinene, beta-pinene, limonene), sesquiterpenes (germacrene C, germacrene A, germacrene B, beta-selinene, delta-selinene, gamma-selinene, (E)-beta-farnesene, gamma-cadinene, nerolidol), diterpenes (geranyl linalool, geranyl geraniol, geranyl geranial), and one sesterterpene (geranyl farnesol). Compounds were purified by HPLC and their structures determined by means of MS spectrometry, or 1D and 2D NMR spectroscopy. Comparison of two different analytical approaches, CC-MS and HPLC with subsequent NMR spectroscopy, revealed Cope rearrangement of germacrene A, germacrene B, and germacrene C to the respective beta-elemene, gamma-elemene, and delta-elemene under GC conditions, thus demonstrating the limits for this analytical approach. The species-specific compound composition provides insight into taxonomy and species origin of European Reticulitermes. The biological significance of the species-specific composition of Reticulitermes defensive secretions is briefly discussed.

Animals↗
PubMed2005

Combining Affymetrix microarray results.

BACKGROUND: As the use of microarray technology becomes more prevalent it is not unusual to find several laboratories employing the same microarray technology to identify genes related to the same condition in the same species. Although the experimental specifics are similar, typically a different list of statistically significant genes result from each data analysis. RESULTS: We propose a statistically-based meta-analytic approach to microarray analysis for the purpose of systematically combining results from the different laboratories. This approach provides a more precise view of genes that are significantly related to the condition of interest while simultaneously allowing for differences between laboratories. Of particular interest is the widely used Affymetrix oligonucleotide array, the results of which are naturally suited to a meta-analysis. A simulation model based on the Affymetrix platform is developed to examine the adaptive nature of the meta-analytic approach and to illustrate the usefulness of such an approach in combining microarray results across laboratories. The approach is then applied to real data involving a mouse model for multiple sclerosis. CONCLUSION: The quantitative estimates from the meta-analysis model tend to be closer to the "true" degree of differential expression than any single lab. Meta-analytic methods can systematically combine Affymetrix results from different laboratories to gain a clearer understanding of genes' relationships to specific conditions of interest.

Algorithms↗
PubMedDate not supplied

[Automated calculation of the RD parameter in euglycemic insulinemic clamp].

The authors proposed a new analytical approach to a search for the RD parameter in euglycemic insulinemic clamp which imparts a rate to glucose infusion. Two diabetic patients were investigated (RD parameter in the first case was determined by intuition, and in the second case--on the basis of mathematical iterative formulas). The analytical approach permitted a two-fold reduction of the time of clamp investigation improving its quality.

Adult↗
PubMed2001

Pharmacological analysis of cannabinoid receptor activity in the rat vas deferens.

1. The interaction between the cannabinoid agonists, WIN 55,212-2 or CP 55,940 with the CB(1) receptor-selective antagonists, SR141716A or LY320135 was investigated using the rat electrically-stimulated vas deferens bioassay. 2. Tissues were stimulated by single-field pulses (150 V, 0.5 ms) delivered every 30 mins. In the presence of nifedipine (3 microM), agonists elicited a concentration-dependent inhibition of the contractile response, with pEC(50) values of 7.93 and 6.84 for WIN 55,212-2 and CP 55,940, respectively. 3. SR141716A and LY320135 caused parallel dextral displacements of the agonist concentration-response curves. However, the shift of the agonist curves by either antagonist was accompanied by a concentration-dependent enhancement of basal (agonist-independent) tissue contraction. 4. Addition of the amidase inhibitor, phenylmethylsulphonylfluoride (200 microM), resulted in a significant reduction of the basal twitch response, an effect consistent with the presence of tonic receptor activation mediated by the endogenous cannabinoid, anandamide. 5. In light of these findings, we propose a theoretical model of competitive agonist-antagonist interaction in the presence of endogenous agonist tone that was used to derive an optimized analytical approach for the determination of antagonist potency estimates under conditions of tonic receptor activation. 6. This approach yielded pK(B) estimates for SR141716A and LY320135 that were in good agreement with their activity at cannabinoid CB(1) receptors. 7. It is concluded that the rat vas deferens contains prejunctional cannabinoid CB(1) receptors that are under tonic activation from endogenous substances; under these conditions our analytical approach is preferable to the standard methods for the determination of antagonist potency.

Animals↗
PubMed2003

Comparative equilibration and online technique for determination of non-exchangeable hydrogen of keratins for use in animal migration studies.

Stable hydrogen-isotope ratios (deltaD) of keratin provide a novel means for tracking geographical movements of birds and other species. Here we describe a rapid, low cost, analytical approach to facilitate online continuous-flow isotope-ratio mass spectrometry (CF-IRMS) deltaD analyses of keratins (120-160 samples per day) through the use of calibrated keratin working standards and "comparative equilibration" to correct for the effects of moisture on exchangeable hydrogen. It is anticipated that this analytical approach and CF-IRMS will greatly aid in providing cost effective and directly comparable deltaD results on keratins and feathers among various laboratories and researchers involved in animal migration studies.

Animals↗
PubMedDate not supplied

Outcome, efficiency, and time-trend pattern analyses for stroke rehabilitation.

We present a series of pattern analysis techniques using inpatient medical rehabilitation as an example setting, stroke as a model diagnosis, and various versions of the Functional Independence Measure-Function Related Groups as a case mix adjuster. The pattern analytic approach uses severity-adjusted benchmarks to distinguish among groups of patients whose outcomes and resource use patterns are lower, typical, or higher than established ranges at set points in treatment. Changing outcome and resource use patterns were illustrated for 1990, 1992, and 1995 discharges (n=34,734). These pattern analytic approaches are applicable to any postacute care rehabilitation setting, assuming the availability of an appropriate case mix adjuster and a reliable patient information system. These techniques provide clinicians with tools to help maintain quality in this era of managed care.

Aged↗
PubMed2005

Summary of contributions to GAW Group 5: linkage mapping methods, Problem 2.

Here I summarize the contributions to Group 5 of Genetic Analysis Workshop 14, held in Noordwijkerhout in The Netherlands. The theme of this group was linkage mapping methods applied to the simulated data (Problem 2). A variety of approaches were taken, and a number of questions were examined. In addition to testing for linkage in regions harboring known disease or modifying loci, or testing for linkage across the genome, the contributions addressed such issues as whether power/significance could be improved by making use of subphenotypes in addition to the primary disease phenotype, by modeling interactions between loci, or by using meta-analytic approaches to combine results from different populations. Most contributions were successful in identifying known disease loci D1 and D2, and for those contributions that examined the relevant regions, in identifying disease loci D3 and D4. The power to detect modifying loci D5 and D6 appeared to be lower. Some gain in power/significance was found from making use of subphenotypes and meta-analytic approaches.

Alcoholism↗
PubMed2002

Improving inter-observer agreement and certainty level in diagnosing and grading papillary urothelial neoplasms: usefulness of a Bayesian belief network.

BACKGROUND AND OBJECTIVE: A Bayesian belief network (BBN), as diagnostic decision support system, enables the processing of our knowledge of histopathology expressed in descriptive terms, words and concepts. The aim of this study was to evaluate the contribution of a BBN in the improvement of inter-observer agreement and certainty level in the diagnosis and grading of papillary urothelial neoplasms. MATERIALS: Inter-observer agreement and certainty level were investigated on 40 cases of non-invasive papillary urothelial neoplasms subdivided according to the WHO 1973 classification. There were 10 urothelial papillomas (UPs), 10 grade 1 papillary carcinomas (G1), 10 grade 2 papillary carcinomas (G2) and 10 grade 3 papillary carcinomas (G3). Five consecutive sessions were held with three observers (RMa, PC and MSt). Sessions A, B and D were based on the morphological evaluation of the specimens with a conventional light microscope only. In sessions C and E, a BBN was used in addition to the microscope. The BBN output was represented by four belief values for four possible diagnostic outcomes. These values ranged from 0.0 to 1.0, with the sum of the belief values being 1.0. Concerning the certainty level, a two-tier system of assessment was adopted in sessions A, B and D: certain versus less certain. In sessions C and E, a belief value equal to or greater than 0.65 was considered as equivalent to "certain". RESULTS: In session A, an all-encompassing or synthetic approach to decision-making was adopted. Agreement with the gold standard was seen in 60% (RMa), 55% (PC) and 65% (MSt) of cases, respectively. The level of subjective confidence was "certain" in 35%, 40% and 35% of cases, respectively. Better agreement-70% (RMa), 68% (PC) and 72% (MSt) of cases-was present in session B where an analytical approach based on the evaluation of a series of morphological features was used. The level of subjective confidence was "certain" in 45%, 50% and 55% of cases, respectively. In session C, where a BBN was utilised, a further increase in degree of agreement with the gold standard was observed, e.g. 85% (RMa), 80% (PC) and 86% (MSt) of cases, respectively. Levels of certainty or belief values were high. Decrease in both the level of agreement-60% (RMa), 62% (PC) and 65% (MSt) of cases-and certainty was seen in session D where the observers were left free to evaluate the cases morphologically without the constrain of either a synthetic or analytical approach. In session E, where the BBN was used again, the percentage of cases in agreement with the gold standard increased to 83% (RMa), 81% (PC) and 84% (MSt), respectively. Increase in certainty or belief was also seen. The difference of the results obtained in the sessions A, B and D with those seen in the BBN-based sessions (C and E) is statistically significant. CONCLUSIONS: Conventional morphological evaluation of papillary urothelial neoplasms is affected by inter-observer variability and, in many instances, by diagnostic uncertainty. The greatest difficulties are found with G1 and G2 cases. Improvement in inter-observer agreement and certainty level can be achieved with a BBN.

Bayes Theorem↗
PubMed2001

Structural characterization of Mycobacterium tuberculosis lipoarabinomannans by the combination of capillary electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) associated with capillary electrophoresis (CE) has been used for structural characterization of mannooligosaccharide caps from Mycobacterium tuberculosis H37rv mannosylated lipoarabinomannans (ManLAMs). The mannooligosaccharide caps were released by mild acid hydrolysis, labeled with 1-aminopyrene-3,6,8-trisulfonate (APTS) prior to being separated by CE, collected, and analyzed by MALDI-TOF-MS and post-source decay experiments. This approach was optimized using standard APTS-labeled oligosaccharides. With the selected (9:1) mixture of 2,5-dihydroxybenzoic acid (DHB) and 5-methoxysalicylic acid (MSA) as matrix and the on-probe sample cleanup procedure with cation-exchange resin, standard APTS-maltotriose was successfully detected down to 50 fmol using linear-mode negative MALDI-TOF-MS. Moreover, using extraction delay time, only 100 and 500 fmol of this standard were required, respectively, to obtain accurate reflectron mass measurements and sequence determination through post-source decay experiments. Applied to only 5 microg (294 pmol) of M. tuberculosis ManLAMs, this analytical approach allowed successful mass characterization of the mannooligosaccharide cap structures from the deprotonated molecular ions [M - H]- and the y-type ion fragments obtained in post-source decay experiments. This powerful analytical approach opens new insights into both the characterization of oligosaccharides and the capping motifs displayed by ManLAMs purified from mycobacteria isolated from tubercular patients without in vitro culturing.

Carbohydrate Conformation↗
PubMed1992

Laryngeal intraepithelial neoplasia (LIN). An analytical morphometric approach.

Laryngeal Intraepithelial Neoplasia (LIN) is graded in 3 levels (LIN Grade I-II-III), corresponding to the classic aspects of mild, moderate and severe dysplasia-in situ carcinoma, on the basis of the number and position of mitoses and of the undifferentiated or atypical cells limited to the basal or extended to the intermediate or the superficial layers of epithelium. In order to reduce the subjective imprecision of these parameters we have applied not only traditional dimensional evaluators but also procedures of analytical morphometry to the nuclear shape. By using the software system S.A.M. (Shape Analytical Morphometry) we have examined fifty nuclei of the basal layer in LIN grade I, II and III, fifty nuclei in normal laryngeal mucosa and fifty nuclei in invasive carcinoma of the larynx (twenty-five cases in all). Normal and dysplastic nuclei did not show any dimensional differences, while the carcinomatous nuclei were significantly larger. An asymmetric distortion of the nuclear contour was noted in the moderate and severe dysplasia, but not in carcinomatous cells. Also the Fourier parameters, increased in severe dysplasia, decreased dramatically in carcinomatous cells which showed nuclei with minor contour irregularities than the normal cells. These findings outline the discriminative power of the analytical morphometry and suggest a possible correlation between nuclear shape and cell biology.

Carcinoma in Situ↗
PubMed2005

A comparison of two data analyses from two observer performance studies using Jackknife ROC and JAFROC.

The authors compared two methodological approaches, Jackknife ROC and JAFROC, in analyzing data ascertained during FROC (free-response receiver operating characteristics) type studies. Observer rating data obtained from two observer performance studies were analyzed. During the first study, seven radiologists interpreted 120 mammography examinations depicting 57 masses under five different conditions with and without the results of computer-aided detection (CAD). In the second study, eight radiologists interpreted 110 examinations depicting 51 masses under six different display conditions with and without CAD results. Readers rated the detection task in a FROC type response. Jackknife ROC (using the software of LABMRMC with the highest rating per case) and JAFROC were used to compute differences, if any, in summary performance levels among all reading modes in each study as well as for all paired data sets. The results of the different analytical approaches are compared. The overall results for all modes were significantly different for the first study (p < 0.05) and not significant (p > 0.05) for the second study using either analytical approach. In the first study, the performance levels represented by three paired data sets were significantly different (p < 0.05) when computed using LABMRMC and four pairs were significantly different (p < 0.05) using JAFROC. In eight of ten pairs, JAFROC produced lower p values than LABMRMC. In the second study, LABMRMC showed no significant differences for any paired data sets and JAFROC showed a significant difference for one pair. In 15 of 16 pairs, p values computed by JAFROC were lower than those computed by LABMRMC.

Breast Neoplasms↗