Systematic literature survey
On March 23, 2018 we executed search queries in the Web of Science and
google scholar with the search term (meta-analys* OR
meta-regression*) AND ecolog* . Google scholar results were compiled
with the software Publish or Perish 6 . The 2,626 publications we
identified were screened for the following inclusion criteria: i) the
research field was ecology (excluding medical, social, financial and
ecosystem service studies), ii) the authors conducted an original
meta-analysis that was based on summary statistics from previous
publications (excluding theoretical, methodological, commentary, raw
data analysis and update studies), iii) the study quantified effect
sizes as either response ratios, mean differences or correlation
coefficients and iv) the authors could or should have applied a
weighting scheme to summarize those effect sizes.
The 505 studies that met these criteria were then screened in order to
extract: i) the year of their publication, ii) the effect size applied
(response ratio, mean difference or correlation coefficient), iii)
whether or not the authors encountered primary studies with missing
variance or sample size information and iv) how the authors dealt with
this missing information. Cases where the authors were vague with
stating how they dealt with missing data (e.g. statements such as “we
extracted all available data”) were classified as missing data
encountered . The Literature search, inclusion criteria, data extracted
and the Preferred Reporting Items for Systematic Reviews and
Meta-Analyses (PRISMA) are reported in the Supplement S2 of the
Supporting Information.