Predicting the time needed for environmental systematic reviews and systematic maps

Area of Science:

• Environmental Science
• Evidence Synthesis

Background:

• Systematic reviews (SRs) and systematic maps (SMs) are vital for evidence synthesis but are resource-intensive.
• Estimates of the time and resources required for SRs and SMs are largely anecdotal.
• Maximizing transparency and minimizing bias are key goals in these rigorous review processes.

Purpose of the Study:

• To estimate the average time requirements for conducting systematic reviews and systematic maps.
• To identify the most time-consuming stages within the SR and SM processes.
• To develop a tool for predicting the time needed for future SRs and SMs.

Main Methods:

• Analysis of 66 systematic reviews and 20 systematic maps from the Collaboration for Environmental Evidence (CEE) published between 2012 and 2017.
• Survey of 33 experienced systematic reviewers to gather data on the completion rates of different review stages.
• Development of a software tool to predict time requirements based on planned methods and evidence base.

Main Results:

• The average CEE systematic review requires an estimated 164 days (full-time equivalent).
• The average CEE systematic map requires an estimated 211 days (excluding critical appraisal).
• Metadata extraction and critical appraisal were found to be as time-consuming, or more so, than title/abstract screening, particularly for systematic maps.

Conclusions:

• This study provides evidence-based estimates for the time and resources needed for SRs and SMs.
• Findings can inform better planning of systematic reviews and maps, directing efforts to streamline time-intensive stages.
• Improved reporting of methods and results by authors can enhance future predictions of review effort.