Showing papers in "Medical Decision Making in 1994"
TL;DR: Large variation in WTP responses may compromise this measure's discriminant validity, but there is some evidence of convergent validity for WTP with preferences measured by standard gamble, and the test-retest reliability of WTP is comparable to those of other preference measures.
Abstract: The development of methods to measure willingness to pay (WTP) has renewed interest in cost-benefit analysis (CBA) for the economic evaluation of health care programs. The authors studied the construct validity and test-retest reliability of WTP as a measure of health state preferences in a survey of 102 persons (mean age 62 years; 54% male) who had chronic lung disease (forced expiratory volume < 70%). Interview measurements included self-reported symptoms, the oxygen-cost diagram for dyspnea, Short-Form 36 for general health status, rating scale and standard gamble for value and utility of current health state relative to death and healthy lung functioning, and WTP for a hypothetical intervention offering a 99% chance of healthy lung functioning and a 1% chance of death. WTP was elicited by a simple bidding game. To test for starting-point bias, the respondents were randomly assigned to one of five starting bids. All health status and preference measurements except WTP (controlling for income) showed significant (p < 0.05) difference between disease-severity groups (mild/moderate/severe). WTP was significantly (p = 0.01) associated with household income, but other health status and preference measure were not. The measure most highly correlated with WTP was standard gamble (r = -0.46). There was no association between starting bid and mean WTP adjusted for income and health status. The test-retest reliability of WTP was acceptable (r = 0.66) but lower than that for the standard gamble (r = 0.82).(ABSTRACT TRUNCATED AT 250 WORDS)
492 citations
TL;DR: The authors recommend systematic inclusion of states worse than death to describe a more complete range of preference values and routine assessment of the cognitive burdens of assessment techniques to evaluate methodologies.
Abstract: Previous research indicates that persons assigning values to ranges of health states consider some states to be worse than death. In a study of decisions regarding life-sustaining treat ments, the authors adapted and assessed existing methods for their ability to identify and quantify preferences for health states near to or worse than death in a population of well adults and nursing home residents. The cognitive burdens involved in these decisions were also evaluated. Hypothetical health states based on six attributes of functional status were constructed to describe severe constant pain, dementia, and coma. The methods of rank order, category scaling, time tradeoff, and standard gamble were adapted to quantify states worse than death. Cognitive burden was assessed using completion rates, interviewer as sessments, respondents' self-reporting, and investigators' evaluations. For both respondent groups, all methods showed similar degrees of cognitive burden for those able to complete the tasks and were sim...
376 citations
TL;DR: The proper definitions and estimations of rates and risks are clarified and critical factors for the decision analyst to re member when using, modeling, or interpreting transition rates and risk are suggested.
Abstract: Confusion regarding proper use of the terms rate and risk persists in the literature. This has implications for the proper modeling of prognosis and transition between health states in decision analysis and related techniques. The issue is complicated by the plethora of terms related to rate and risk. Although the suggestion to use the terms force and probability as substitutes for rate and risk has some appeal, the change in terminology by itself is unlikely to solve all the confusion or misuse of terms. This paper clarifies the proper definitions and estimations of rates and risks and suggests critical factors for the decision analyst to remember when using, modeling, or interpreting transition rates and risks.
189 citations
TL;DR: Omission bias plays a role in decisions not to vaccinate with pertussis vaccine, beyond the role played by belief about the risk of vaccination.
Abstract: Background: Several laboratory studies have suggested that many people favor potentially harmful omissions over less harmful acts. The authors studied the role of this omission bias in parents' decisions whether to vaccinate their children against pertussis. Methods: Two hundred mail surveys were sent to subscribers to a magazine that had published articles favoring and opposing pertussis vaccination. Subjects were asked about their beliefs about the vaccine and the disease, and whether they had vaccinated their own children or planned to, and they were given test items to identify omission bias in their reasoning. Results: One hundred and three subjects (52%) responded to the survey. Respondents who reported they did not or would not allow their children to be vaccinated (n = 43; 41 %) were more likely to believe that vaccinating was more dangerous than not vaccinating (p < 0.001 ). They were also more likely to exhibit omission bias (p = 0.004), holding constant their stated beliefs about the danger of ...
188 citations
TL;DR: In this paper, the authors investigated whether adjustment of TTO scores for the utility of life years (risk attitude) eliminated this difference, and the association between risk attitude and sociodemographic and medical variables was studied.
Abstract: The standard gamble (SG) and the time tradeoff (TTO), two frequently used methods of utility assessment, have often been found to lead to different utilities for the same health state. The authors investigated whether adjustment of TTO scores for the utility of life years (risk attitude) eliminated this difference. In addition, the association between risk attitude and sociodemographic and medical variables was studied. In 30 disease-free testicular cancer patients, SG and TTO were used to assess the utilities of four health profiles relevant to testicular cancer. Utility of life years was estimated from certainty equivalents (CEs). SG scores were significantly higher than unadjusted TTO scores for all profiles. As the majority of patients (85%) were risk-averse, CE-adjusted TTO scores were higher than unadjusted scores, and were not significantly different from those obtained from the SG for three of the four profiles. However, adjusted scores were still slightly but consistently lower than SG scores. Po...
187 citations
TL;DR: It is concluded that pooling life-table data without adjustment for covariates can be misleading and indication, lesion type, vein graft availability, and site of the distal graft anastomosis need to be considered in predicting patency results of revascular ization for femoropopliteal arterial disease.
Abstract: To estimate the patency results of percutaneous transluminal angioplasty and bypass surgery in the treatment of femoropopliteal arterial disease, a Medlars search of the English-language medical literature was performed. Inclusion required that studies 1) report original data, 2) report patency with a life table or Kaplan-Meier analysis with the number at risk or standard errors, 3) define patency as hemodynamic improvement, 4) report the distribution of covariates, and 5) not duplicate other published material. Using a method based on the proportional-hazards model and the actuarial life-table approach, the results were adjusted for differences in case-mix of the study populations and patency was predicted for subgroups at various levels of risk for failure. The unadjusted pooled life tables yielded five-year patencies of 45% (+/- 2%) for angioplasty, 73% (+/- 2%) for bypass surgery using a vein graft, and 49% (+/- 3%) for bypass surgery using a polytetrafluoroethylene graft. Adjusted five-year primary patencies after angioplasty varied from 12% to 68%, the best results being for patients with claudication and stenotic lesions. Adjusted five-year primary patencies after surgery varied from 33% to 80%, the best results being for saphenous vein bypass performed for claudication. The authors conclude that pooling life-table data without adjustment for covariates can be misleading. Indication, lesion type, vein graft availability, and site of the distal graft anastomosis need to be considered in predicting patency results of revascularization for femoropopliteal arterial disease.
157 citations
TL;DR: The authors establish a theoretical health care example with three diagnostic strategies and demonstrate, both algebraically and geometrically, how to calculate the set of all possible mixed strategies that dominate the strategy eliminated by extended dominance.
Abstract: The principle of extended dominance is applied in incremental cost-effectiveness analysis to eliminate from consideration strategies whose costs and benefits are improved by a mixed strategy of two other alternatives. Ethical considerations arise, however, in that equal care is not provided to all of the population. To explore these concerns, the authors establish a theoretical health care example with three diagnostic strategies. They demonstrate, both algebraically and geometrically, how to calculate the set of all possible mixed strategies that dominate the strategy eliminated by extended dominance. With the consideration of budget constraints, they define the "coefficient of inequity" as the minimum proportion of the population that would receive an inferior health care strategy if a mixed strategy were to be used instead of the dominated strategy. The implications of cost-effectiveness analysis are made explicit, revealing classic economic concerns about the tradeoff of equity and efficiency.
128 citations
TL;DR: The author demonstrates that the greatest clinical utility is not always achieved by using the most specific test in a rule-in decision or the most sensitive test in an rule-out decision.
Abstract: Previous publications have advocated that clinicians choose the most sensitive diagnostic test to rule out disease and the most specific diagnostic test to rule in disease. This paper critically ex...
121 citations
TL;DR: It is shown that discounting of QALYs is inconsistent withThese assumptions, and the time-tradeoff method to be consistent with these assumptions is shown.
Abstract: The theoretical model of QALYs is based on risk neutrality with respect to life years or constant proportional risk posture with respect to life years. It is shown that discounting of QALYs is inco...
104 citations
TL;DR: This methodology is applied to a CDC guideline for the prevention of perinatal transmission of hepatitis B by immunization, demonstrating that the hepatitis guideline is incomplete.
Abstract: Clinical practice guidelines can be clarified, verified, and simplified by the use of logical analysis and the application of decision-table techniques. This methodology is applied to a CDC guideli...
87 citations
TL;DR: The authors elicited utilities at two occasions by the certainty equivalent method from 30 women from the general population and the respondents gave certainty equivalents to gambles with years of life, consistent with prospect theory and may explain why patients opt for risky treatments.
Abstract: According to prospect theory, risk attitude changes depending on whether a prospect is perceived as a gain or a loss relative to a reference or aspiration level. To investigate risk attitude with respect to years of life, the authors elicited utilities at two occasions by the certainty equivalent method from 30 women from the general population. The respondents gave certainty equivalents to gambles with years of life. The gambles were two-outcome gambles with equal probabilities to experience each outcome. A shift from a risk-seeking towards a risk-averse attitude was observed with increasing expected value of the gambles. For each individual, the averaged responses over the two replications were fitted with an s- shaped logistic curve that showed an excellent fit (r2 ≥ 0.97) for all respondents. The aspiration level of survival can be derived from this function and was negatively correlated with age (r = -0.43, p < 0.025). The data are consistent with prospect theory and may explain why patients opt for ...
TL;DR: Patients' preferences for gallstone-related conditions generally are significantly less than one, and differ markedly by the scaling technique used to derive them, which should be considered when patient preferences are incorporated into analyses of gallstone treatments.
Abstract: To estimate patient preferences for gallstone-related treatments and outcomes, and assess how preferences vary by patient characteristics and scaling technique, the authors randomly assigned 40 patients without gallstones to interviews based on a rating scale (n = 22) and a standard gamble (n = 18). The patients assigned preference values (possible values 0 to 1) to open cholecystectomy (mean 0.45 by rating scale, 0.78 by standard gamble), laparoscopic cholecystectomy (0.71, 0.91), extracorporeal shock-wave lithotripsy (0.77, 0.89), acute cholecystitis (0.36, 0.77), lifetime biliary colic (0.41, 0.71), postcholecystectomy syn drome (0.43, 0.79), asymptomatic stone necessitating treatment with bile acids (0.76, 0.96), and surgical scar (0.79, 0.998). Preferences varied little by age, gender, or race. Standard gamble values were highly correlated with, but significantly greater than, rating scale values. The authors conclude that patients' preferences for gallstone-related conditions generally are significa...
TL;DR: Residents and experienced surgeons more often agreed on treatment decisions when chance information was presented in numerical terms as compared with verbal terms, and physicians were less confident when verbal terms were presented, but only for the less familiar decision problems.
Abstract: Verbal probability terms are frequently used in medical practice. In the present experiment the use of verbal and numerical probability terms in medical decisions was investigated. Interns, residents in surgery and internal medicine, surgeons, and internists were asked to make treatment decisions for three different cases (acute appendicitis, angina pectoris, and an imaginary disease) and were also asked to give numerical interpretations of a series of verbal probability terms. In the second stage of the experiment the respondents received the same cases, but with numerical probability terms. The results showed no effect of context or of domain experience on the interpretation of verbal terms. Residents and experienced surgeons more often agreed on treatment decisions when chance information was presented in numerical terms as compared with verbal terms. Physicians were less confident when verbal terms were presented, but only for the less familiar decision problems. Finally, phy sicians turned out to be ...
TL;DR: In patients with suspected acute myocardial infarction, IVSK saves lives and is a reasonable use of societal resources.
Abstract: Objective: To determine the effects of infarct location and of the likelihood of infarction on the cost-effectiveness of intravenous streptokinase (IVSK) for suspected acute myocardial infarction (AMI) Design: A meta-analysis of short-term survival was combined with a simple decision tree to determine marginal cost-effectiveness ratios for different infarct locations and different likelihoods of AMI (pMI) Setting: Six randomized trials comparing IVSK with conservative treatment Patients: 31,940 patients with onset of symptoms of AMI from four to 24 hours earlier and, with the exception of one trial, electrocardiographic abnormalities Patients with contraindications to thrombolytic treatment such as uncontrolled hypertension were excluded Main results: If AMI is certain, treatment with IVSK has marginal cost- effectiveness ratios for each additional life saved of $9,900, $56,600, and $28,400, respec tively, for patients with anterior, inferior, and other locations of AMI If pMI is 50%, treatment with
TL;DR: The authors present a formal method for determining the cost-effectiveness of incorporating the preferences of individual patients into clinical practice guidelines based on utilities assessed from 37 patients in the setting of mild hypertension.
Abstract: Many clinical practice guidelines fail to account for the preferences of the individual patient. Approaches that seek to include the preferences of the individual patient in the decision-making process (e.g., interactive videodisks for patient education), however, may incur substantial incremental costs. Developers of clinical practice guidelines must therefore determine whether it is appropriate to make their guidelines flexible with regard to patient preferences. The authors present a formal method for determining the cost-effectiveness of incorporating the preferences of individual patients into clinical practice guidelines. Based on utilities assessed from 37 patients, they apply the method in the setting of mild hypertension. In this example, they estimate that the cost-effectiveness ratio for individualized utility assessment is $48,565 per quality-adjusted year of life, a ratio that compares favorably with other health interventions that are promoted actively. This approach, which can be applied to any clinical domain, offers a formal method for determining whether the incorporation of individual patient preferences is important clinically and is justified economically.
TL;DR: The patients' treatment preferences for long-term vs short-term survival benefits were influenced by the amounts of verbal explanation provided to them about five-year survival graphs summarizing treatment results, which appeared to minimize the importance of medium-range data when those data were not specifically pointed out to them.
Abstract: Objective: To evaluate the influence of physicians' explanations on patients' choices. Setting: A university-based Department of Veterans Affairs Medical Center. Participants: 136 patients seen in a continuity-care general medicine clinic. Measurements and Results: Patients were randomized to two groups [Limited Explanation (LE) and Extensive Explanation (EE)] and asked to choose between two alternative treatments (differing in short-term vs long-term survival benefits) for an unidentified medical condition, based on the information given in the explanations. LE consisted of a brief orientation to graphs summarizing the treatment results, while EE consisted of a detailed verbal description of the graphs. Significantly (p < 0.001) more patients receiving EE changed their preferences across three pairs of five-year survival curves, compared with patients receiving LE. Of the patients receiving EE, 57% reported either medium-term (year 0-to-intercept or intercept-to-year 5) data or the average life expectanc...
TL;DR: This work develops closely matched MM and Text descriptions of health states in the first-person narrative style, and develops a method of testing the presentation of a health state.
Abstract: Quality-adjustment weights for health states are an essential component of cost-utility analysis (CUA). Quality-adjustment weights are obtained by presenting large numbers of subjects with multiattribute descriptions of health states for rating. Comprehending multiattribute health states is a difficult task for most respondents. The authors hypothesized that multimedia (MM) presentation using computers might facilitate this task better than would a paper-based text (Text). To test this hypothesis, they developed closely matched MM and Text descriptions of health states in the first-person narrative style, and developed a method of testing the presentation of a health state. Subjects were randomized to exposure to either MM or Text and subject recall of the health state and recognition of features of the health state were tested. How well defined the preferences of the subjects were after each presentation method was assessed by having the subjects mark on a double-anchored visual-analog scale the "best" and "worst" they believed the quality of life in the health state might be. MM subjects had better recall (11.85 vs 9.44 of a total of 24 meaning units, p = 0.098) and better recognition (4.71 vs 4.22, p = 0.08). The average interval between the "best" and "worst" ratings was shorter for the MM subjects (2.19 cm vs 3.26 cm, p = 0.12).(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: One implication of these findings is that this network, which has been shown to perform with a high degree of diagnostic accuracy, may be doing so by identifying relationships between inputted information that are divergent from accepted teaching.
Abstract: An artificial neural network trained to identify the presence of myocardial infarction has been shown to function with a high degree of accuracy. The effects on network diagnosis of some of the clinical input variables used by this network have previously been shown to be distributed over two distinct maxima. Analysis of the basis for this distribution by studying the specific patterns in which these variables had significantly different impacts on network diagnosis revealed that the differential impacts were due to the contexts in which the variables whose effects were bimodally distributed were placed. These contexts were defined by the values of the other input data used by the network. In a number of instances, the clinical relationships implied by these associations were divergent from prior knowledge about factors predictive of myocardial infarction. One implication of these findings is that this network, which has been shown to perform with a high degree of diagnostic accuracy, may be doing so by identifying relationships between inputted information that are divergent from accepted teaching.
TL;DR: The diagnostic value of a scoring models model has little external validity and it is concluded that the application of these models may lead to more efficient diagnosis and prevent somatization.
Abstract: Scoring models based on history and physical examination have been developed to dis criminate patients with non-organic gastrointestinal disease from those who have organic disease. The application of these models may lead to more efficient diagnosis and prevent somatization. Although the models have high diagnostic accuracy in the population in which they have been developed, their value in other populations has not been established. In this study previously developed models were tested in validation populations defined by the original selection criteria from the studies in which the models were developed and in un selected general practice and outpatient populations. The diagnostic performances of the models are expressed in terms of odds ratio and sensitivity and specificity for the classification of patients as having organic and non-organic disease. The diagnostic performances of all the models were rather low in the validation populations. Relatively few elements of the models had independent diagno...
TL;DR: It is demonstrated that an expert panel's appropriateness ratings and their expected utilities were highly correlated, and the panelists appeared to be internally consistent in that their judgments about individual probabilities and utilities were correlated with their global judgments.
Abstract: A widely used method for evaluating the appropriateness of medical procedures and practices is the "modified Delphi" approach using expert panelists' global ratings. However, several difficulties in the assignment of global ratings have led to a search for alternative methods, including the use of decision models. To examine the potential impact of using decision models with an expert panel, the authors compared a panel's global ratings for the appro priateness of carotid endarterectomy with the results of a decision-analytic model in which expert panelists estimated probabilities and utilities that were used as inputs for the model. For 17 different patient scenarios, the nine expert panelists showed variability in "calibration" between the two methods, with their expected utilities calculated from the model generally being higher than their global ratings. However, the correlation between the two methods was excellent. When the panel's median global utility was compared with the panel's median expected ...
TL;DR: The study showed that self-reported data collected by a computer are as reliable as data obtained through a written questionnaire and that clients are more willing to respond to computer interviews than to mailed written questionnaires.
Abstract: This paper suggests a new approach for lowering follow-up costs, improving the delivery of health care, and monitoring treatment outcomes. An automated telephone follow-up system that calls, identifies, and interviews clients is an alternative method for monitoring patients that may be both reliable and cost-effective. To test the viability of such a system, the authors monitored a patient population that has historically been shown to be difficult to follow: recovering drug users and alcoholics. Forty-two subjects were asked to call the computer and complete interviews on a weekly basis for five months. Clients answered 25 recorded questions by pressing the keys on their telephone pads. The computer automatically analyzed the clients' answers and estimated a probability of relapse for each client. In addition, the computer automatically called subjects who failed to complete interviews at the scheduled times. The study showed that self-reported data collected by a computer are as reliable as data obtaine...
TL;DR: The authors conclude that pooling studies without considering the effect of case-mix yields an average result with inappropriately narrow confidence intervals that does not reflect the variability across subgroups.
Abstract: The objective of this study was to present and illustrate a technique for combining failure-time data from various sources, adjusting for differences in case-mix among studies. Based on the proportional-hazards model and the actuarial life-table approach, the method used assumes that the variation across studies is in part due to heterogeneity of the case-mix and adjusts for the case-mix before pooling results. As an example, the technique is applied to life-table data from six selected papers reporting patency of affected arteries following femoropopliteal angioplasty. Published 4- and 5-year patency results ranged from 25% to 58%, with a pooled five-year cumulative patency rate (without adjustment for case-mix) of 45% (+/- 2%). The populations in these studies, however, differed markedly in the prevalence of factors with prognostic value: type of lesion and distal runoff vessels. After adjustment for these differences in case-mix, the pooled five-year patency rates ranged from 60% (+/- 2%) for patients with stenotic lesions and good runoff to 24% (+/- 9%) for those with occlusion and poor runoff. The authors conclude that pooling studies without considering the effect of case-mix yields an average result with inappropriately narrow confidence intervals that does not reflect the variability across subgroups. The presented technique provides a method for combining failure-time data, adjusting for case-mix.
TL;DR: Based on the results of randomized drug trials, it is concluded that the cost-effectiveness of hypertension treatment improves with patient age for both men and women.
Abstract: The aim of this study was to investigate whether any consistent pattern exists with respect to the cost-effectiveness of hypertension treatment and age, based on the results of ran domized drug trials. Data about age, entry diastolic blood pressure, and relative risks of coronary heart disease (CHD) and stroke from 19 randomized trials were used to derive point estimates of the cost-effectiveness of each trial. The relationship between age and cost per life-year gained was then estimated by regression analysis, controlling for entry diastolic blood pressure. The regression analysis shows a statistically significant average decrease in the cost per life-year gained of about SEK 15,000 per year of older age for both men and women ($1 = SEK 6). Sensitivity analysis showed that the improvement in cost- effectiveness with age was stable towards various assumptions, but that the magnitude of the improvement varied greatly with the discount rate. Based on the results of randomized drug trials, it is concluded th...
TL;DR: The results imply that careful consultation with health professionals to determine the content of a decision analysis or informational materials that address treatment choice is sufficient to address patient concerns and that items can be chosen for inclusion based on the relative frequencies with which they are mentioned.
Abstract: For an illness whose treatment options lead to similar survival, quality-of-life issues determine the choice. If the patient has not yet experienced the treatments, then the information provided regarding the options plays a crucial role in the patient's choice. The authors interviewed 43 people who are intimately involved with the treatments for end-stage renal disease (ESRD) (ten physicians, 11 nurses, and 22 patients) with a view to determining what information needs to be considered when choosing between the various treatment options for this illness. They compared the three groups based on the items obtained from the interviews to deter mine whether the inclusion of patients in the process changed the content of the treatment descriptions. They were also interested in determining whether the use of the frequency with which an item is mentioned in the interviews is a valid measure of its relative importance to other items. 1,269 relevant items were obtained from the interviews and categorized into 51 ...
TL;DR: The authors present equations for estimating the area under the ROC curve and the AUC when only one pair of a true- and a false-positive rate is given, for inherently logistically and normally distributed data.
Abstract: Many measures, including sensitivity and specificity, predictive values, and likelihood ratios, are available for the assessment of diagnostic tests. A drawback of the use of these measures is that...
TL;DR: A computer program to construct decision models automatically that has the potential to enable novices to construct useful decision models and to provide individualized decision-analytic advice to clinicians in real time.
Abstract: Clinical application of decision analysis has been limited by unfamiliarity of clinicians with the technique, large data requirements, and the length of time needed to construct models. In order to make decision modeling more accessible to clinicians, the authors developed a computer program to construct decision models automatically. The system contains two separate knowledge bases. One contains frames encoding knowledge of the medical domain, the evaluation of pulmonary disease in patients infected with the human immunodeficiency virus (HIV). The other contains rules of correct decision model construction that guide the selection of items from the domain knowledge base and their insertion into the decision model. The system can create either a tree or an influence diagram that satisfies previously published critiquing rules. The system has the potential to enable novices to construct useful decision models and to provide individualized decision-analytic advice to clinicians in real time. Key words: inte...
TL;DR: The authors conclude that a dementia screening program for older drivers would be cost-beneficial if physician evaluations were limited or their cost lowered to ≤$60, or if physician referral costs were lowered to $60 per evaluation.
Abstract: A Markov model was used to assess the cost-benefit ratios of six strategies of screening older drivers for mental status, beginning at age 65. Probabilities of motor vehicle collisions (MVCs), injuries, and fatalities were obtained from national data. Dementia prevalence, test characteristics, and costs were obtained from the literature. Costs included lost wages, car ownership, alternative transportation, and injuries. Using a relative risk of MVC for those with dementia of 5 and a 5% annual discounting rate, the average cost per driver ranged from $51,600 (no testing) to $58,400 (testing every five years). The benefit was < one day of life gained, and the benefits of screening cost approximately 2.8 million dollars per life-year gained. Increasing the relative risk from 5 to 20 substantially improved the cost-benefit of mental status screening. However, mental status screening of older drivers would also be cost-beneficial if physician referral costs were lowered to $60 per evaluation. The authors conclude that a dementia screening program for older drivers would be cost-beneficial if physician evaluations were limited or their cost lowered to < or = $60.
TL;DR: The tradeoff between avoiding active tuberculosis and avoiding isoniazid-related side effects is the most important factor in the decision regarding the proper management of patients with positive tuberculin tests and the importance of taking an individualized approach to the management of these patients is emphasized.
Abstract: To provide insight into the decision whether to use isoniazid prophylaxis in uncomplicated cases of positive tuberculin tests, the authors conducted a multicriteria decision analysis using the anal...
TL;DR: The authors consider the role of misclassification costs in developing classification trees by varying the ratio of costs assigned to false negatives and false positives, and a set of sensitivity-specificity combinations define a curve that can be used like an ROC curve.
Abstract: A common problem in medical diagnosis is to combine information from several tests or patient characteristics into a decision rule to distinguish diseased from healthy patients. Among the statistical procedures proposed to solve this problem, recursive partitioning is appealing for the easily-used and intuitive nature of the rules it produces. The rules have the form of classification trees, in which each node of the tree represents a simple question about one of the predictor variables, and the branch taken depends on the answer. The authors consider the role of misclassification costs in developing classification trees. By varying the ratio of costs assigned to false negatives and false positives, a series of classification trees are generated, each optimal for some range of cost ratios, and each with a different sensitivity and specificity. The set of sensitivity-specificity combinations define a curve that can be used like an ROC curve.
TL;DR: The three authors refer to the gambler’s fallacy and propose that individuals’ time preferences may disagree with the economic model called discounting, but that this does not vitiate the justification for the model.
Abstract: The three authors refer to the gambler’s fallacy. They note that people’s actions support the fallacy, but that this action does not discredit probability theoiy. They extend this logic by proposing that individuals’ time preferences may disagree with the economic model called discounting, but that this does not vitiate the justification for the model. This argument is flawed because it neglects the purpose of an economic model,