Background and context: The variables that researchers measure and how they measure them are central in any area of research, including computing education. Which research questions can be asked and how they are answered depends on measurement. Objective: To summarize the commonly used variables and measurements in computing education and to compare them to best practices in measurement for human-subjects research. Method: Systematic literature review analyzing 197 papers published during 2013-2017 in computing education research venues. Findings: The review illuminates common practices related to: variables measured (including learner characteristics), measurements used, and type of data analysis. The paper lists standardized measurements that were used and highlights commonly used variables for which no standardized measures exist. Implications: The paper concludes with information about best practices currently being used in the community that should be continued, as well as pointing out practices that could be improved along with recommendations for how to begin to adopt those best practices.