Carroll has a problem with the use of parent report to attain quantity of language exposure measures in inquiry on bilingual development. When debating parent questionnaires, Carroll writes “Temporal units are crude measures of exposure and they tell us nothing about input”. Whilst this paper assents that temporal units do not tell much about the fine-grained details of the input within the temporal units, importantly, parent-report-based measures of input quantity have predicted variation in bilingual development of phonology, vocabulary and morphosyntax. These are robust and trustworthy findings across many studies, and yet, Carroll skates over them as if they did not matter, or rejects them as petty. Farther, Carroll seems to lead readers to think that only coarse-grained, language-use temporal units have been attained via this method; on the contrary, researchers have attained fine-grained input quality details via parent report that also predict bilingual children's evolution. Finally, in some circumstances, parent report data is the only executable method for attaining language exposure information.