| Cross-sectional study | Reports outcomes for a particular timepoint for a cohort |
| Economic model studies | Studies assessing the cost-effectiveness or economic impact of an intervention |
| Narrative review | Analysis and summary of topics related to productivity based on existing literature, with no systematic search for all relevant publications. |
| Prospective observational | Participants observed over time in their natural environment |
| Prospective, interventional | Participants followed up over time after being allocated to a new intervention. If the intervention is being compared to another intervention or a control group, the allocation is not randomised. |
| Randomized controlled trial | Participants are allocated to intervention arms at random, so any difference in outcomes is likely to be due to differences in the interventions. |
| Retrospective observational | Analysis of existing data from study participants that was collected in the past. |
| Systematic literature review or meta analysis | A summary of all relevant published literature on the topic, with publications identified based on a systematic search. |