A wide variety of methodological choices and situations can affect the quality of peer nomination measurements but have not received adequate study. This article begins by focusing on systematic nominator missingness as an example of one such situation. We reanalyzed findings from a recent study by Bukowski, Dirks, Commisso, Velàsquez, and Lopez in the year 2019 [see EJ1235048] and compared the results to recent findings of Babcock, Marks, van den Berg, and Cillessen published in the year 2018 [see EJ1163382] to show that systematic nominator missingness can, indeed, have an impact on nomination measures. From there, we discuss the importance of considering sources of error and the ways that sources of error are analyzed. Ultimately, we argue that systematic nominator missingness is one of several potential sources of error that have largely been ignored in the literature, and that analyzing and reporting these sources of error would strengthen the foundations of peer nomination research.