Study designs of evaluations included in the review
There was no apparent restriction on study design, other than the need for comparative data. Relevant studies from peer-reviewed journals, technical and government reports, and unpublished reports were included, as were studies from the US or other countries. Most of the studies included in the review were surveys.
Specific interventions included in the review
The use of ROPS on agricultural tractors. Interventions that influenced the implementation of ROPS, such as legislation and education, were also included.
Participants included in the review
Operators of agricultural tractors, regardless of age, gender or race/ethnicity, were included.
Outcomes assessed in the review
There were two primary categories of outcome, namely implementation of ROPS and fatalities. Nonfatal injury and occurrence of a roll-over incident were also included for some studies. Studies were excluded if they did not objectively measure outcomes, or if they did not contain interpretable data.
How were decisions on the relevance of primary studies made?
The studies were selected for inclusion as described previously (see Other Publications of Related Interest). The abstracts or titles were screened by two independent experts using standardised criteria to identify potentially eligible articles. If an abstract or title met the screening criteria, a full copy of the study was retrieved. A standardised checklist was then used by two independent raters to determine whether the retrieved articles should be included. The authors of the review then abstracted each study, judged methodological quality, and made the final decisions on which articles to include.