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PubMedDate not supplied

Probabilities of eventually developing or dying of cancer--United States, 1985.

The usual measures of the magnitude of the cancer problem are annual incidence and mortality data. We present another measure of the magnitude of the cancer problem. We computed the probabilities at birth and at various ages of developing or dying of the disease within 10 years, 20 years, or total lifetime and show the trends that have occurred in these data since 1975. These probabilities were computed for males and females and among whites and blacks for 1975 and 1980, and projected to 1985. The data indicate a continuing, albeit modest, increase in the probabilities of eventually developing cancer in each of the four sex-race groups, both excluding and including carcinoma in situ. White males now show the highest probability at birth of eventually developing cancer, and black females, the lowest, with the figures for the other two groups being intermediate. Larger increases were seen for males between 1980 and 1985 (more than three percent) than for females (two percent or less). A child born in the US in 1985 has more than one in three chances of eventually developing invasive cancer (exclusive of epidermoid skin cancer). By site, for males the largest probabilities and the largest increases in the probabilities are for eventually developing lung and prostate cancer. For women, the largest eventual probabilities are for breast cancer, almost one in 10 for white females and one in 14 for black females. The largest increases are seen for lung cancer and cancer of the colon-rectum. The probability of eventually dying of cancer is increasing among the four sex-race groups and is now greater for males of both races than for their female counterparts. For males born in 1985, the chances of eventual death from cancer are almost one in four, and for females, almost one in five. With the long-term, downward trends in terms of other causes of death--most specifically, decreases in mortality from cardiovascular diseases--the effect on the population at large is greater longevity. This situation, in turn, leaves more people longer time to be exposed to cancer risks. Thus, while the probabilities of developing or dying of cancer are seen to increase, the increases should be viewed in light of the increasing numbers of people available for such an occurrence.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMedDate not supplied

[Choice between probability and value of alimentary reinforcement as means for revealing individual typological features of dog behavior].

Individual typological features of behavior of dogs were investigated by the method of choice between the low-valuable food available constantly and food of high quality presented with low probability. Animals were subjected to instrumental conditioning with the same conditioned stimuli but different types of reinforcement. Depression of a white pedal was always reinforced with meat-bread-crumb mixture, depression of a black pedal was reinforced with two pieces of liver (with probabilities of 100, 40, 33, 20, or 0%). The choice of reinforcement depended on probability of valuable food and individual typological features of the nervous system of a dog. Decreasing the probability of the reinforcement value to 40-20% revealed differences in behavior of dogs. Dogs of the first group, presumably with the weak type of the nervous system, more frequently pressed the white pedal (always reinforced) than the black pedal thus "avoiding a situation of risk" to receive an empty cup. They displayed symptoms of neurosis: whimper, refusals of food or of the choice of reinforcement, and obtrusive movements. Dogs of the second group, presumably with the strong type of the nervous system, more frequently pressed the black pedal (more valuable food) for the low-probability reward until they obtained the valuable food. They did not show neurosis symptoms and were not afraid of "situation of risk". A decrease in probability of the valuable reinforcement increased a percentage of long-latency depressions of pedals. It can be probably suggested that this phenomenon was associated with increasing involvement of cognitive processes, when contributions of the assessments of probability and value of the reinforcement to decision making became approximately equal. Choice between the probability and value of alimentary reinforcement is a good method for revealing individual typological features of dogs.

Animals↗

PubMed1989

Bone marrow donor registries: the relation between registry size and probability of finding complete and partial matches.

In a registry of volunteer bone marrow donors, the relation between registry size and probability of finding an exact or partial match for a random recipient cannot be theoretically derived because it depends on specifics of the human leukocyte antigen (HLA) haplotype frequencies in the donor and recipient populations. The relation must be explicitly calculated using empirically determined HLA haplotype frequency data for all possible pairings between a donor and a recipient population. This report describes a general solution to this problem. The method shows that the relation of the probability of matching to registry size is sigmoidal, with small increases in probability at the extremes of registry size and a middle range of registry size within which the probability of matching increases most sharply. This range determines the approximate size of the most cost-effective registry. In addition, for any pairing of donor and recipient populations, there is a maximum probability of identifying a match of a given quality for a random recipient, which cannot be exceeded even if registry size were infinite. This upper limit is a function of the frequency of blank (or unknown) alleles in the donor and recipient populations; the higher that frequency, the lower the maximum probability of achieving any given quality of match. The determinants of the probability of achieving a given quality of match with a given registry size are (1) the genetic heterogeneity within the recipient and donor populations, which increases the registry size required to achieve a given probability of matching, and (2) the degree of genetic homology between the donor and recipient populations, which increases the maximum probability of matching and also lowers registry size requirements. The method described here can be used to estimate donor pool size requirements using any donor and recipient populations for which HLA frequency data are available.

Bone Marrow Transplantation↗

PubMed1986

Probability and paternity testing.

A probability can be viewed as an estimate of a variable that is sometimes 1 and sometimes 0. To have validity, the probability must equal the expected value of that variable. To have utility, the average squared deviation of the probability from the value of that variable should be small. It is shown that probabilities of paternity calculated by the use of Bayes' theorem under appropriate assumptions are valid, but they can vary in utility. In particular, a recently proposed probability of paternity has less utility than the usual one based on the paternity index. Using an arbitrary prior probability in the calculation cannot lead to a valid probability unless, by chance, the chosen prior probability happens to be appropriate. Appropriate assumptions regarding both the prior probability and gene or genotypic frequencies can be estimated from prior experience.

Female↗

PubMed2002

Studies on single-cell adhesion probability between lymphocytes and endothelial cells with micropipette technique.

An in vitro model with micropipette technique was used to investigate single-cell adhesion probability between lymphocytes and endothelial cells. The basal adhesion probability between lymphocytes and endothelial cells was low and was significantly increased when either lymphocytes were activated by phytohemagglutinin (PHA) or endothelial cells were stimulated by tumor necrosis factor. The adhesion probability of lymphocytes to human umbilical vein endothelial cells was similar to that of lymphocytes to human brain microvascular endothelial cells (HB-MVEC). However, lymphocyte adhesion probability was higher in HB-MVEC than in mouse brain microvascular endothelial cells (MB-MVEC) under both resting and activated conditions. Furthermore, lymphocytes preincubated with monoclonal antibodies to lymphocyte function-associated antigen-1 (LFA-1) or HB-MVEC preincubated with monoclonal antibodies to intercellular adhesion molecule 1 (ICAM-1) significantly down-regulated the adhesion probability between lymphocytes and endothelial cells, indicating that the adhesion probability is related to the expression of LFA-1 on lymphocytes and to the expression of ICAM-1 on endothelial cells. Lymphocytes isolated from patients with cerebral stroke exhibited increased adhesion probability to HB-MVEC as compared with lymphocytes from healthy donors. Preincubation of lymphocytes with tetramethylpyrazine (TMP), an extract from a Chinese traditional herb, effectively inhibited the adhesion probability to HB-MVEC, suggesting that TMP has a potential therapeutic value. These results indicate that the micropipette technique is a useful model for investigating single-cell adhesion probability between lymphocytes and endothelial cells in vitro.

Animals↗

PubMedDate not supplied

Release probability is regulated by the size of the readily releasable vesicle pool at excitatory synapses in hippocampus.

Synapses in the central nervous system can be very unreliable: stimulation of an individual synapse by an action potential often does not lead to release of neurotransmitter. The probability of transmitter release is not always the same, however, which enables the average strength of synaptic transmission to be regulated by modulation of release probability. Release probability is believed to be determined by the number of fusion competent vesicles (the readily releasable vesicle pool) and the release probability per vesicle. Studies from single synapses have shown that release probability correlates with the size of the readily releasable pool of vesicles across the population of excitatory CA3-CA1 synapses, both in hippocampal slices and in cultured cells. Here I present evidence that the same relationship exists between release probability and the size of the readily releasable vesicle pool within individual synapses, further suggesting that the size of the readily releasable pool helps determine release probability. In addition, using a simple model, I examine how both the number of readily releasable vesicles and the average release probability per vesicle change during trains of high frequency stimulation, and present evidence for non-uniformity of the release probability among vesicles.

Animals↗

PubMed2003

Probability analysis for diagnosis of endometrial hyperplasia and cancer in postmenopausal bleeding: an approach for a rational diagnostic workup.

OBJECTIVE: To develop an analytical approach to estimate the probability of endometrial hyperplasia and cancer in women with postmenopausal bleeding, using a combination of patient history and tests. METHODS: A prospectively collected database of 428 postmenopausal women investigated for abnormal uterine bleeding in an outpatient rapid access clinic was used. The probability of disease was estimated using multivariable logistic regression models considering a combination of age and the use of hormone replacement therapy (HRT) and tests (ultrasound and hysteroscopy) in keeping with the actual clinical process. RESULTS: The prevalence or prior probability of endometrial cancer in the sample studied was 4.4%. Hysteroscopy alone performed better than ultrasound alone. In all patients, a negative hysteroscopy reduced the probability of cancer to 1.3%. In women less than 60 years of age who use HRT, a negative hysteroscopy further reduced this probability to 0.1%. Overall, a positive hysteroscopy raised the probability of cancer to 38.9%. However, in women over 60 years of age not using HRT, a positive hysteroscopy increased this probability to 59.4%. Combining ultrasound results with hysteroscopy did not meaningfully alter the diagnostic probability. CONCLUSION: The combination of information obtained from patient history and tests allows generation of specific disease probabilities in postmenopausal bleeding. This type of multivariable analysis puts diagnostic information gained from history and other tests into a perspective that reflects actual clinical practice.

Databases, Factual↗

PubMed2004

Use of different D-dimer levels to exclude venous thromboembolism depending on clinical pretest probability.

Currently, the same D-dimer cut-off point is used to define a positive result for all patients with suspected venous thromboembolism, regardless of their pretest probability. However, use of a relatively high D-dimer cut-off point (lower sensitivity) for those with a low clinical pretest probability, and a low D-dimer cut-off point (higher sensitivity) for those with a high clinical pretest probability, may be preferable. To determine if using three different D-dimer cut-off points according to low, moderate or high clinical pretest probability has greater utility for exclusion of venous thromboembolism than using the same single D-dimer cut-off point in all patients. Data from a previously published study of 571 patients was used to identify the highest D-dimer cut-off point with a negative predictive value of at least 98% for the subgroup of patients with low and high pretest probability. The D-dimer cut-off point for those with moderate clinical pretest probability remained unchanged [0.5 fibrinogen equivalent units (FEU) microgram mL(-1)]. Accuracy of D-dimer testing for venous thromboembolism using three cut-off points vs. one cut-off point was than determined. D-dimer cut-off points of 0.2 and 2.1 FEU microgram mL(-1) were selected for the high and low pretest probability groups, respectively. When three pretest probability-specific cut-off points were used instead of the previously determined single D-dimer cut-off point (0.5 FEU microgram mL(-1)), sensitivity and negative predictive value were unchanged (95 and 98%, respectively), but specificity increased from 44.7 to 60.4% (P < 0.001). This resulted in exclusion of venous thromboembolism in 80 additional patients. Use of three pretest probability-specific D-dimer cut-off points rather than a single D-dimer cut-off point for all patients, has the potential to increase the utility of D-dimer testing for the diagnosis of venous thromboembolism.

Algorithms↗

PubMed2005

Probable cigarette dependence, PTSD, and depression after an urban disaster: results from a population survey of New York City residents 4 months after September 11, 2001.

Disaster exposure may exacerbate psychopathology and substance-related disorders. Four months after September 11, 2001, using random-digit dialing to contact a representative sample of adults (N = 2001) living in New York City, we assessed cigarette smoking and symptoms of probable cigarette dependence using measures from the National Survey on Drug Use and Health. A total of 36.8% of smokers reported increased cigarette use; 10.4% of respondents reported three or more symptoms of cigarette dependence and were considered cases of probable cigarette dependence based on DSM-IV criteria. Cases were more likely to report an increase in cigarette use since September 11 than non-cases (69.4% among cases vs. 2.2% among non-cases, p < 0.001). Cases were more likely to have probable posttraumatic stress disorder (PTSD) and depression than non-cases (18.1% vs. 5.7% for PTSD, p < 0.001; 23.6% vs. 6.0% for depression, p < 0.001). Increased cigarette use since September 11 was associated with probable PTSD among cases (23.4% vs. 6.4%, p = 0.011) and non-cases (15.1% vs. 5.5%, p = 0.034) but was associated with probable depression only among cases of probable cigarette dependence (28.3% vs. 13.3%, p = 0.027). This study showed the co-occurrence of probable cigarette dependence with increased cigarette use and the co-occurrence of probable cigarette dependence with probable PTSD and depression after September 11.

Adolescent↗

PubMed1993

Ordering genes: controlling the decision-error probabilities.

Determination of the relative gene order on chromosomes is of critical importance in the construction of human gene maps. In this paper we develop a sequential algorithm for gene ordering. We start by comparing three sequential procedures to order three genes on the basis of Bayesian posterior probabilities, maximum-likelihood ratio, and minimal recombinant class. In the second part of the paper we extend sequential procedure based on the posterior probabilities to the general case of g genes. We present a theorem that states that the predicted average probability of committing a decision error, associated with a Bayesian sequential procedure that accepts the hypothesis of a gene-order configuration with posterior probability equal to or greater than pi *, is smaller than 1 - pi *. This theorem holds irrespective of the number of genes, the genetic model, and the source of genetic information. The theorem is an extension of a classical result of Wald, concerning the sum of the actual and the nominal error probabilities in the sequential probability ratio test of two hypotheses. A stepwise strategy for ordering a large number of genes, with control over the decision-error probabilities, is discussed. An asymptotic approximation is provided, which facilitates the calculations with existing computer software for gene mapping, of the posterior probabilities of an order and the error probabilities. We illustrate with some simulations that the stepwise ordering is an efficient procedure.

Algorithms↗

PubMed1993

Evaluation of physician decision making with the use of prior probabilities and a decision-analysis model.

OBJECTIVES: To determine whether treatment decisions could be influenced by supplying probabilities and whether these decisions would be consistent with a decision-analysis model. DESIGN: Survey with case scenarios and a computerized decision-analysis model. SETTING: Family practice residency program. PARTICIPANTS: Forty family practice residents and faculty in the experimental group and six controls. INTERVENTIONS: Twelve cases scenarios of patients with hypertension and coexisting diseases were developed. Family practice physicians were asked to rank their drugs of choice for each case. In the second phase, six case scenarios included probabilities for efficacy and adverse reactions of step 1 antihypertensives. These drug selections were compared with a computerized decision-analysis model. MAIN OUTCOME MEASURES: Frequencies of matches between the drug selections of physicians and the computer model. RESULTS: The frequency of matches before probabilities were provided to physicians was low (45.6%) and there was a significant increase when probabilities were supplied (71.3%). Regardless of experience level, physicians increased their consistency with the computer model after probabilities were supplied. CONCLUSIONS: This study demonstrated that physician decision making for antihypertensive therapy can be influenced by patient-specific probability estimates. Probability data can help less experienced residents make decisions that are comparable to those of attending physicians. This study was conducted in one residency program and the generalizability to the practicing physician is unknown. These findings would suggest that educational efforts in residency programs, health maintenance organizations, or group practices may benefit from patient-specific probabilities that assist with decisions for drug therapy interventions.

Adult↗

PubMed2001

Assessing clinical probability of pulmonary embolism in the emergency ward: a simple score.

OBJECTIVE: To develop a simple standardized clinical score to stratify emergency ward patients with clinically suspected pulmonary embolism (PE) into groups with a high, intermediate, or low probability of PE to improve and simplify the diagnostic approach. METHODS: Analysis of a database of 1090 consecutive patients admitted to the emergency ward for suspected PE in whom diagnosis of PE was ruled in or out by a standard diagnostic algorithm. Logistic regression was used to predict clinical parameters associated with PE. RESULTS: A total of 296 (27%) of 1090 patients were found to have PE. The optimal estimate of clinical probability was based on 8 variables: recent surgery, previous thromboembolic event, older age, hypocapnia, hypoxemia, tachycardia, band atelectasis, or elevation of a hemidiaphragm on chest x-ray film. A probability score was calculated by adding points assigned to these variables. A cutoff score of 4 best identified patients with low probability of PE. A total of 486 patients (49%) had a low clinical probability of PE (score </=4), of which 50 (10.3%) had a proven PE. The prevalence of PE was 38% in the 437 patients with an intermediate probability (score of 5-8; n = 437) and 81% in the 63 patients with a high probability (score >/=9). CONCLUSIONS: This clinical score, based on easily available and objective variables, provides a standardized assessment of the clinical probability of PE. Applying this score to emergency ward patients suspected of having PE could allow a more effective diagnostic process.

Adolescent↗

PubMed1994

How age, outcome severity, and scale influence general medicine clinic patients' interpretations of verbal probability terms.

OBJECTIVE: To assess whether the type of scale used (scaling effects) and the severity of outcome (outcome severity) influence patients' numerical interpretations of verbal probability expressions. DESIGN: Cross-sectional survey of patients in a general medicine clinic. SETTING: A university-based Department of Veterans Affairs Medical Center. PARTICIPANTS: 210 patients seen consecutively in a general medicine clinic. MEASUREMENTS AND RESULTS: The patients were randomized to scale and health outcome (complications of surgery). Two scales (a long form and a short form) were used to expressly allow patients to choose probabilities less than 1%. The long form had a lower bound of "< 1 out of 1,000,000"; the short form had a lower bound of "< 1 out of 1,000." Two complications were used: "death from anesthesia" and "severe pneumonia." In the context of being told that their surgeon believed that the chance the complication would occur was "rare," patients were asked to give the numerical estimate of that chance. The values elicited on both scales were significantly different for the two outcomes, with the "rare" risk of death from anesthesia being characterized as less likely than the "rare" risk of severe pneumonia (F = 5.24, p = 0.023). Linear regression and three-factor analysis of variance showed significant differences in the probabilities elicited for scale, outcome, and age, with older patients generally responding with higher probabilities than did younger patients. CONCLUSIONS: These findings suggest that the severity of the associated outcome and the scale used to elicit patients' numerical estimates of verbal probability expressions influence patients' quantitative interpretations of the verbal probability statement; and older patients respond with higher probabilities of negative outcomes than do younger patients. Future studies must continue to explore whether verbal probability expressions are adequate for communicating medical risk to patients or whether patients should be provided with numerical estimates of frequency.

Adult↗

PubMed2002

Dimensional measures of psychopathology. The probability of being classified with a psychiatric disorder using empirically derived symptom scales.

OBJECTIVES: We sought to develop a ranking scheme that assigns a probability of having one of four psychiatric disorders to children based on their scores on a symptom scale. We then estimated the impact of each scale symptom on the prevalence of the disorder in the population. METHOD: Logistic regressions were specified for ADHD, ODD, depressive, and conduct disorders using all the individual symptoms in the pertinent scale as predictors. Individual fitted values from the regression function then served as a probability scale measure. We combined the prevalence and influence of each scale symptom to calculate its overall impact on the prevalence of the disorder. RESULTS: Probability distributions had a wide range of values and discriminated between cases and non-cases. Those having a disorder were consistently associated with higher probabilities in the scale. The estimated probability corresponds to the empiric prevalence of the diagnosis in a group of persons sharing the same estimated probabilities. Symptoms varied on their impact on the prevalence of the disorder. CONCLUSIONS: We recommend the estimated probability of the disorder based on the empirically defined scales as dimensional measures that complement prevalence of the disorder. Different symptoms are identified as targets for screening when selection is based on their impact on the prevalence of the disorder than when selection is based on the strength of the association with the disorder. We recommend using a common nosology with different classification schemes; the categorical definition of the disorder, the probability of having the disorder, and the impact of each symptom in the prevalence. Different measures serve different purposes.

Adolescent↗

PubMed2005

Differential effects of target probability on saccade latencies in gap and warning tasks.

Saccade latencies are significantly reduced by extinguishing a foveal fixation stimulus before the appearance of a saccade target. It has been shown recently that this "fixation offset effect" (FOE) can be modulated by varying target probability. Cortico-collicular top-down effects have been assumed to mediate this strategic FOE modulation. Here, we have investigated strategic FOE modulation in 14 healthy human subjects performing gap and warning tasks. In the former task, the central fixation point was extinguished 200 ms before target onset. In the latter task, the central fixation point changed its colour 200 ms before target onset, but remained illuminated until the target appeared. Target probability was varied block-wise between 25 and 75%. In both tasks, mean latencies decreased with increasing target probability. However, in contrast with what can be expected from preceding studies, we found no differential modulation of mean latencies by target probability between tasks. Instead, we observed differential probability-dependent changes in latency distributions. In the gap task, discrete changes of saccade latencies were found, with a probability-dependent change in frequency of express and regular latencies. By contrast, in the warning task a shift of the entire latency distribution towards longer latencies with low target probability was found. We conclude that strategic modulation of saccade latencies by target probability may be mediated by two distinct neural mechanisms. Selection of either mechanism seems to depend critically on activation of the fixation system.

Adult↗

PubMed1988

Reliability of Bayesian probability analysis for predicting coronary artery disease in a veterans hospital.

To assess the accuracy of Bayesian probability analysis for the prediction of coronary artery disease, post-test probabilities were generated by the application of three Bayesian algorithms to the clinical and noninvasive test results of 199 patients undergoing angiography in a veterans' hospital. All assumed conditional independence but each used different pre-test and conditional probabilities. Two statistical approaches were employed: (1) Sorting of patients in ascending deciles of probability and comparing expected and observed probabilities in each decile. (2) Calculation of normally distributed reliability statistics which do not depend on probability subsets and the comparison of resulting probability distributions using these statistics. Both statistical approaches revealed that the Bayesian algorithms overestimated disease probability when it was high and underestimated it when low. Though all three algorithms were frequently incorrect, they differed significantly in their accuracies, suggesting that errors in Bayesian analysis are caused by factors other than the assumption of independence. The errors may be due to differences in sensitivity and specificity of tests applied in different institutions.

Adult↗

PubMed2006

Simplicity and probability in causal explanation.

What makes some explanations better than others? This paper explores the roles of simplicity and probability in evaluating competing causal explanations. Four experiments investigate the hypothesis that simpler explanations are judged both better and more likely to be true. In all experiments, simplicity is quantified as the number of causes invoked in an explanation, with fewer causes corresponding to a simpler explanation. Experiment 1 confirms that all else being equal, both simpler and more probable explanations are preferred. Experiments 2 and 3 examine how explanations are evaluated when simplicity and probability compete. The data suggest that simpler explanations are assigned a higher prior probability, with the consequence that disproportionate probabilistic evidence is required before a complex explanation will be favored over a simpler alternative. Moreover, committing to a simple but unlikely explanation can lead to systematic overestimation of the prevalence of the cause invoked in the simple explanation. Finally, Experiment 4 finds that the preference for simpler explanations can be overcome when probability information unambiguously supports a complex explanation over a simpler alternative. Collectively, these findings suggest that simplicity is used as a basis for evaluating explanations and for assigning prior probabilities when unambiguous probability information is absent. More broadly, evaluating explanations may operate as a mechanism for generating estimates of subjective probability.

Adult↗

PubMed2006

Distinct neuropsychological processes may mediate decision-making under uncertainty with known and unknown probability in gain and loss frames.

Decision-making under uncertainty has been studied in psychiatry, economic psychology, and neuroeconomics. Psychiatric patients (e.g., drug addicts) often show low degrees of aversion to potential danger. Investigation into neuropsychological processing underlying decision under uncertainty is important for medical treatments of neuropsychiatric disorders. In economic decision theory, choices under uncertainty with and without known probabilities of outcomes have been discriminated. Regarding decision-making under uncertainty with known probabilities (risk), Kahnemann-Tversky's prospect theory revealed that people tend to avoid uncertainty in potential gains (i.e., risk-aversion in a gain-frame); on the contrary, prefer uncertainty in potential losses (i.e., risk-seeking in a loss-frame). Regarding choices between possible gains with known and unknown probabilities, Ellsberg demonstrated that, in a gain-frame, people tend to avoid uncertainty with unknown probabilities, more dramatically than uncertainty with known probabilities. This can be explained by risk/uncertainty aversion in the gain-frame, suggesting that uncertainty with known and unknown probabilities (i.e., risk and Knightian uncertainty, respectively) may possibly be processed by similar neuropsychological processing in the gain-frame. However, in spite of accumulating evidence in neuroimaging and neuroeconomic studies, it is still unknown whether probability and Knightian uncertainty in the loss-frame are mediated by similar neuropsychological processes as well. We propose that distinct neuropsychological processes may mediate potential losses with known and unknown probabilities, based on recent findings in neuroeconomics and our experiment. Importance of examining subjects' degree of Knightian uncertainty aversion for the prediction/treatment of drug addicts' risky behavior (e.g., needle-sharing) is also discussed.

Decision Making↗