This paper presents a case for the use of transaction-level data when analyzing automated online assessment results to identify knowledge gaps and misconceptions for individual students. Transaction-level data, which records all of the steps a student uses to complete an assessment item, are preferred over traditional assessment formats that submit only the final answer, as the system can detect persistent misconceptions. In this study we collected transaction-level data from 996 students enrolled in an online introductory spreadsheet class. Each student's final answer and step-by-step attempts were coded for misconceptions or knowledge gaps regarding the use of absolute references over four assessment occasions. Overall, the level of error revealed was significantly higher in the step-by-step processes compared to the final submitted answers. Further analysis suggests that students most often have misconceptions regarding non-critical errors. Data analysis also suggests that misconceptions identified at the transaction level persist over time.