<p>Evidence from scientific research results and both formal and informal data can support teachers in optimizing student learning environments and in enhancing their own professional development. However, unconscious cognitive biases, particularly the anchoring effect, can be barriers to effective evidence-informed practice (EIP). Although previous studies on the anchoring effect demonstrate a&#xa0;robust effect in various contexts, this bias has not yet been explored in the context of EIP. In line with the two components of EIP (scientific research results and data), this article addresses two research questions, based on experimental designs: To what extent do anchors influence 1.&#xa0;the evaluation of research results and 2.&#xa0;data collection? Based on two different samples (<i>N</i>_<i>1</i> = 220 and <i>N</i>_<i>2</i> = 113) of student teachers in Germany, statistical analyses were performed using (repeated measures) ANOVAs and Welch’s t‑test, with Approximated Adjusted Fractional Bayes Factors (AAFBFs) estimated for each. These show in study&#xa0;1 strong relative evidence for anchoring effects in the evaluation of research results, with effect sizes ranging from small to large depending on the anchor condition. In study&#xa0;2, AAFBFs also provide strong relative evidence for anchoring effects during data collection. This suggests that two key steps in the EIP process are prone to bias: the evaluation of research results and the data collection, both of which influence the subsequent decisions made based on them. The findings can serve as a&#xa0;foundation for developing debiasing strategies.</p>