10.1371/journal.pone.0161929.g001 Antonia E. Dalziel Antonia E. Dalziel Steven Delean Steven Delean Sarah Heinrich Sarah Heinrich Phillip Cassey Phillip Cassey Systematic review PRISMA chart[40]. Public Library of Science 2016 Quantitative Meta-Analysis Avian influenza viruses factor effect-size Low Pathogenic Influenza influenza virus future LPAIV persistence variable 2016-10-13 17:30:22 Figure https://plos.figshare.com/articles/figure/Systematic_review_PRISMA_chart_40_/4029660 <p>The chart illustrates the inclusion/exclusion process of reviewing studies and the numbers of papers identified at each stage (n). The forward and backward reference search was conducted at the eligibility stage. The number of samples (k) are provided for the five key variables: temperature, pH, water type, H-type and salinity. An example of the temperatures and number of observations is also given.</p>