A Concept Inventory (CI) is an assessment to measure student conceptual understanding of a particular topic. This article presents the results of a CI for basic data structures (BDSI) that has been previously shown to have strong evidence for validity. The goal of this work is to help researchers or instructors who administer the BDSI in their own courses to better understand their results. In support of this goal, we discuss our findings for each question of the CI using data gathered from 1,963 students across seven institutions.