Primary versus secondary source of data in observational studies and heterogeneity in meta-analyses of drug effects: a survey of major medical journals
Abstract Background The data from individual observational studies included in meta-analyses of drug effects are collected either from ad hoc methods (i.e. “primary data”) or databases that were established for non-research purposes (i.e. “secondary data”). The use of secondary sources may be prone...
Main Authors: | , , , , |
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Format: | Article |
Language: | English |
Published: |
BMC
2018-09-01
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Series: | BMC Medical Research Methodology |
Subjects: | |
Online Access: | http://link.springer.com/article/10.1186/s12874-018-0561-3 |