In the first part of our analysis we use the classical network measures in order to describe topological properties of the maritime trade network derived from the Lloyd's Shipping Index publications.
The frequency of repeated occurrence of index publications in SRs (N) is divided by the product of index publications (r) and reviews (c), minus by the number of index publications (r; see calculation formula).
There is a delay in indexing publications in Medline thus more recent publications may have been missed.
In addition, we performed the Medline search on 15 January 2013, for publications up to 1 January 2013, and delays in indexing publications on Medline can exceed two weeks.
We covered several databases, including those indexing publications in the areas where pickled vegetables are highly consumed; we searched publications in Chinese as well as in English.
We included original research, reviews, meta-analyses, guidelines, responses, letters, commentaries, and editorials that were not written by the authors of the index publications.
35 % of the index publications were cited in two to three SRs and about 29%% in four to six SRs (Table 1).
This was used to determine overlap N is the number of publications included (with duplicate counts) in the evidence synthesis of individual SRs; r is the number of index publications (individual primary studies) and c the number of SRs.
The number of primary studies per SR varied from 6 to 66. Taken together, the ten SRs covered a total of 143 primary studies (index publications); these were cited up to 314 times in the SRs.
CCA can be interpreted as the overlap area of studies that occur at least twice in SRs, after correction for the first time each primary study was counted (index publications).
Most of the research has been conducted by, or in collaboration with, the Bandim Health Project (BHP), a Danish-Guinean research collaboration which has produced by far the largest part of the nearly 650 research publications that originate from Guinea Bissau (Pubmed indexed publications excluding commentaries).
