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Population Proportions (population + proportion)

Distribution by Scientific Domains

Medical Sciences	40%
Humanities and Social Sciences	40%

Selected Abstracts

The incidence of intra-operative awareness during general anesthesia in China: a multi-center observational study

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 7 2009
L. XU
Background: The incidence of awareness in patients undergoing general anesthesia is 0.1,0.2% in Western countries. The medical literatures about awareness during general anesthesia are still rare in China, but some previous studies have reported a higher incidence (1.4,6%) of intra-operative awareness. To find out the reason why the incidence reported in China is much higher than that in Western countries, we performed a prospective, multicenter, non-randomized observational study to determine the true incidence of intra-operative awareness in China. Methods: This is a prospective, non-randomized descriptive cohort study that was conducted at 25 academic medical centers in China. Eleven thousand one hundred and eighty-five patients were interviewed by research staff for evaluation of awareness at the first and fourth day after general anesthesia with muscle relaxation. An independent blinded committee evaluated the responses and determined whether awareness occurred. Necessary data were collected for a binary logistic regression analysis. Results: Data from 11,101 patients were presented. Forty-six cases (0.41%) were reported as definite awareness and 47 additional cases (0.41%) as possible awareness. Three hundred and fifty-five patients (3.19%) had dreams during general anesthesia. Awareness was associated with increased American Society of Anesthesiologists (ASA) physical status, a previous anesthesia, and anesthesia methods of total intravenous anesthesia. Conclusion: The incidence of intra-operative awareness in China is approximately 0.41%, two to three times higher than that widely cited in Western countries. Inappropriately light anesthesia, and the population proportion of surgery and general anesthesia in China may account for the difference. (ClinicalTrials.gov Identifier, NCT00693875.) [source]

Logistic Population Growth in the World's Largest Cities

GEOGRAPHICAL ANALYSIS, Issue 4 2006
Gordon F. Mulligan
This article demonstrates that recent population growth in the world's largest cities has conformed to the general parameters of the logistic process. Using data recently provided by the United Nations, logistic population growth for 485 million-person cities is analyzed at 5-year intervals during 1950,2010, with the UN projections for 2015 adopted as upper limits. A series of ordinary least-squares regression models of increasing complexity are estimated on the pooled data. In one class of models, the logarithms of population proportions are specified to be linear in time, which is the standard approach, but in a second class of models those proportions are specified as being quadratic. The most complex models control logistic growth estimates for (i) city-specific effects (e.g., initial population), (ii) nation-specific effects (e.g., economic development, age distribution of population), and (iii) global coordinates (for unobserved effects). Moreover, the results are segregated according to each city's membership in four different growth clubs, which was an important finding of previous research. [source]

How to Cut the Seigniorage Cake into Fair Shares in an Enlarged EMU

JCMS: JOURNAL OF COMMON MARKET STUDIES, Issue 5 2007
JØRGEN DRUD HANSEN
The European Central Bank redistributes each year seigniorage from issuing euro notes to the National Central Banks of the euro countries. The key for this redistribution is, from 2008, based on the respective GDP and population proportions of the euro countries. Applying the distribution formula to the new EU countries from central and eastern Europe seems to give these countries a large net benefit compared with the seigniorage they bring in, i.e. their share of currency in circulation. However, as argued in this article, currency demand in the new EU member countries is expected to increase relative to the present group of euro countries , especially after gaining membership in the EMU because of integration of the financial markets and, in the longer term, catching-up growth. Hence, it is doubtful whether a large unintended redistribution of seigniorage to the benefit of acceding EMU countries will materialize in the future. [source]

Multivariate tests comparing binomial probabilities, with application to safety studies for drugs

JOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES C (APPLIED STATISTICS), Issue 4 2005
Alan Agresti
Summary., In magazine advertisements for new drugs, it is common to see summary tables that compare the relative frequency of several side-effects for the drug and for a placebo, based on results from placebo-controlled clinical trials. The paper summarizes ways to conduct a global test of equality of the population proportions for the drug and the vector of population proportions for the placebo. For multivariate normal responses, the Hotelling T2 -test is a well-known method for testing equality of a vector of means for two independent samples. The tests in the paper are analogues of this test for vectors of binary responses. The likelihood ratio tests can be computationally intensive or have poor asymptotic performance. Simple quadratic forms comparing the two vectors provide alternative tests. Much better performance results from using a score-type version with a null-estimated covariance matrix than from the sample covariance matrix that applies with an ordinary Wald test. For either type of statistic, asymptotic inference is often inadequate, so we also present alternative, exact permutation tests. Follow-up inferences are also discussed, and our methods are applied to safety data from a phase II clinical trial. [source]

Estimating the risk of rare complications: is the ,rule of three' good enough?

ANZ JOURNAL OF SURGERY, Issue 7-8 2009
John Ludbrook
Abstract The clinical problem:, If a surgeon has performed a particular operation on n consecutive patients without major complications, what is the long-term risk of major complications after performing many more such operations? Examples of such operations are endoscopic cholecystectomy, nephrectomy and sympathectomy. The statistical problem and solutions:, This general problem has exercised the minds of theoretical statisticians for more than 80 years. They agree only that the long-term risk is best expressed as the upper bound of a 95% confidence interval. We consider many proposed solutions, from those that involve complex statistical theory to the empirical ,rule of three', popular among clinicians, in which the percentage risk is given by the formula 100 × (3/n). Our conclusions:, The ,rule of three' grossly underestimates the future risks and can be applied only when the initial complication rate is zero (that is, 0/n). If the initial complication rate is greater than zero, then no simple ,rule' suffices. We give the results of applying the more popular statistical models, including their coverage. The ,exact' Clopper,Pearson interval has wider coverage across all proportions than its nominal 95%, and is, thus, too conservative. The Wilson score confidence interval gives about 95% coverage on average overall population proportions, except very small ones, so we prefer it to the Clopper,Pearson method. Unlike all the other intervals, Bayesian intervals with uniform priors yield exactly 95% coverage at any observed proportion. Thus, we strongly recommend Bayesian intervals and provide free software for executing them. [source]