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Every School Day Counts: The Forum Guide to Collecting and Using Attendance Data
NCES 2009-804
February 2009

Challenge: Overlapping and/or Nonexhaustive Taxonomies

Every school or school district maintains student attendance records. However, not all record systems distinguish attendance conditions clearly. Categories can be so broad that the information is of limited usefulness: "present" and "absent" cover most situations but do not tell a teacher or administrator whether a student is ill or simply "cutting class." On the other hand, if lists of reasons for absenteeism are too long, record keepers are likely to use only a few of the codes. The codes must be easily understood. If it is difficult for the person filling out the attendance form to judge what category an incident of absenteeism falls into, the information provided will be unreliable. All of these data quality problems make the information less useful. And, the less data are used, the less likely it is that attention will be paid to data quality.

An exhaustive taxonomy
accounts for all attendance scenarios without using an "other" code.

A mutually exclusive taxonomy
provides only one possible code for each attendance scenario.

A set of attendance code choices—a taxonomy—that cannot account for all attendance scenarios without use of an "other" code invariably results in a loss of information about the absence. A taxonomy that does not adequately distinguish its terms permits overlap in attendance scenarios; in other words, more than one code may be appropriate for a single situation. If the school's taxonomy is not exhaustive and mutually exclusive, data will not be accurately categorized and data quality will suffer. Schools, districts, and states also need a taxonomy of attendance codes that are feasible to collect accurately and on a regular basis. The number of codes should be adequate to categorize every student attendance scenario, yet not so granular to be unmanageable.

RECOMMENDATION: ESTABLISH A COMPREHENSIVE, YET MANAGEABLE TAXONOMY. A key to improving the quality of attendance data is establishing a taxonomy that covers all situations with minimal chance of confusion. This publication presents a taxonomy that is an exhaustive, mutually exclusive set of codes that document a student's attendance status at any given time. By its "exhaustive" nature, the taxonomy accounts for the full range of possible attendance scenarios that may arise in a K–12 education setting. "Mutually exclusive" means that each situation can be categorized by only one code. In the context of attendance codes, this means that one and only one code is necessary and sufficient to categorize any student's attendance status. Such a taxonomy is presented in chapter 2 of this document.