The "Defining and determining which quantitative study designs to include in your systematic review of effects of a healthcare intervention" guidance aims to help Cochrane authors consider two key questions: 

1. Should non-randomised studies of interventions (NRSI) be included in your systematic review of the effects of a health care intervention?; and, if so,
2. What types of NRSI design may help answer review questions about intervention effects?

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It has been developed primarily for systematic reviews of the effects of healthcare interventions in public health. NRSI are defined in the Cochrane Handbook for Systematic Reviews of Interventions as any quantitative study estimating the effects of an intervention (benefit or harm) that does not use randomization to allocate individuals (or groups of individuals) to intervention groups. 

This guidance was developed as part of a collaborative programme of work aimed at delivering practical resources to help authors and editors translate guidance from the Cochrane Handbook for Systematic Reviews of Interventions into practice.