In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

Ex Input:
Context: To systematically review methodological articles which focus on nonpublication of studies and to describe methods of detecting and/or quantifying and/or adjusting for dissemination in meta-analyses. To evaluate whether the methods have been applied to an empirical data set for which one can be reasonably confident that all studies conducted have been included.', 'We systematically searched Medline, the Cochrane Library, and Web of Science, for methodological articles that describe at least one method of detecting and/or quantifying and/or adjusting for dissemination bias in meta-analyses.', 'The literature search retrieved 2,224 records, of which we finally included 150 full-text articles. A great variety of methods to detect, quantify, or adjust for dissemination bias were described. Methods included graphical methods mainly based on funnel plot approaches, statistical methods, such as regression tests, selection models, sensitivity analyses, and a great number of more recent statistical approaches. Only few methods have been validated in empirical evaluations using unpublished studies obtained from regulators (Food and Drug Administration, European Medicines Agency).\Question: Are methods for detecting , quantifying , and adjusting for dissemination bias in meta-analysis described?

Ex Output:
We present an overview of existing methods to detect, quantify, or adjust for dissemination bias. It remains difficult to advise which method should be used as they are all limited and their validity has rarely been assessed. Therefore, a thorough literature search remains crucial in systematic reviews, and further steps to increase the availability of all research results need to be taken.


Ex Input:
Context: To determine the extent of genetic variation among internationally collected HIV-1 isolates, to analyse phylogenetic relationships and the geographic distribution of different variants.', 'Phylogenetic comparison of 70 HIV-1 isolates collected in 15 countries on four continents.', 'To sequence the complete gag genome of HIV-1 isolates, build multiple sequence alignments and construct phylogenetic trees using distance matrix methods and maximum parsimony algorithms.', 'Phylogenetic tree analysis identified seven distinct genotypes. The seven genotypes were evident by both distance matrix methods and maximum parsimony analysis, and were strongly supported by bootstrap resampling of the data. The intra-genotypic gag distances averaged 7%, whereas the inter-genotypic distances averaged 14%. The geographic distribution of variants was complex. Some genotypes have apparently migrated to several continents and many areas harbor a mixture of genotypes. Related variants may cluster in certain areas, particularly isolates from a single city collected over a short time.\Question: Does phylogenetic analysis of gag genes from 70 international HIV-1 isolates provide evidence for multiple genotypes?

Ex Output:
The genetic variation among HIV-1 isolates is more extensive than previously appreciated. At least seven distinct HIV-1 genotypes can be identified. Diversification, migration and establishment of local, temporal 'blooms' of particular variants may all occur concomitantly.


Ex Input:
Context: This study examines the relationship between the existence of chest wall tenderness evoked by palpation and the absence of ischemic heart disease defined by myocardial perfusion imaging in patients with known or suspected stable angina pectoris.', 'Two hundred seventy-five patients were recruited. Myocardial perfusion imaging was performed on 273 of the subjects. Chest pain was classified according to type by criteria given by the Danish Society of Cardiology and severity by the Canadian Cardiovascular Society. Pectoralis major and pectoralis minor were palpated for tenderness using a standardized procedure.', 'The association between tenderness and myocardial perfusion imaging (normal vs abnormal) produced an odds ratio (OR) of 2.24 (confidence interval, 1.26-3.99; P = .009). The OR was the same magnitude and significance when stratified by sex, age, type of pain, or class. When adjusting simultaneously for sex, age, type of pain, and class, the association between tenderness and myocardial perfusion imaging (normal vs abnormal) was still present (OR = 2.57; confidence interval, 1.342-4.902; P = .004).\Question: Is muscular tenderness in the anterior chest wall in patients with stable angina pectoris associated with normal myocardial perfusion?

Ex Output:

Presence of tenderness in the anterior chest wall is associated with a higher prevalence of normal myocardial perfusion imaging in patients with known or suspected angina pectoris, and this association cannot be explained by a common association to age, sex, or pain.