Authors: Pärt, Tomas; Josefsson, Jonas;Hiron, Matthew ;Kačergytė, Ineta;Rubene, Diana;Knape, Jonas;Auffret et al., Alistair ;

The delivery of rigorous and unbiased evidence on the effects of interventions lies at the heart of the scientific method. We examine scientific papers evaluating agri-environment schemes, the principal instrument to mitigate farmland biodiversity declines worldwide. Despite previous warnings about poor study designs in this field, we found that the majority of studies published between 2008 and 2017 still lack robust study designs required to evaluate intervention effects. Potential sources of bias that arise from the correlative nature of data are rarely mentioned, and results are still promoted by using a causal language. This lack of robust study designs likely results from poor integration of research and policy, while the erroneous use of causal language and an unwillingness to discuss bias may stem from publication pressures. As these violations to the scientific method can have serious repercussions on the general view concerning conservation research we propose some practices to improve scientific reporting and discussion of study limitations in intervention research.