All raters provided informed consent (parental consent, as well as assent from the youth, were received for Self-Report forms) and were given standardized instructions on how to complete the Conners 4 and, where applicable, the other instruments used for the validity studies (see chapter 9, Validity study details). All raters were compensated for taking part in the data collection process (see Standardization Phase in chapter 6, Development).

For the Parent and Teacher raters, the majority completed the Conners 4 remotely (via an emailed link). For the Self-Report, youth completed the test locally at an administrator’s office.

Raters were eligible for inclusion if they lived in the U.S. or in Canada and indicated that they were able to read English “well” or “very well” (note that for the Self-Report, if the youth could not read English well, they were not excluded from the study, but had the items read aloud to them by a trained administrator). In order to complete the Parent and Teacher forms, the youth being rated had to be between 6 and 18 years of age. For the Self-Report form, the youth rated themself and had to be between 8 and 18 years of age. Teachers were required to have known the student for at least one month and must have indicated that they knew them “moderately well” or “very well.” Teachers were required to have interacted with the student on a daily, weekly, or monthly basis over the past three months, and they had to be able to answer questions about the student’s gender, age, race/ethnicity, and the state or province in which the student lives.

After data collection, all data were cleaned prior to analyses. Cases were removed from analyses if there were any possible concerns about the validity of the data collected due to: (a) insufficient adherence to instructions (e.g., Teacher reported not currently teaching the student, or the Self-Report was completed with the parent’s assistance [rather than independently by the youth or read aloud by a trained administrator]); (b) incorrect responses to at least two out of three possible instructed items (e.g., “Please respond Never for this item” must result in a selection of“Never” to be valid); (c) omitting more than 3% of the total items in the survey (note that 3% was selected as a threshold for omitted responses as nearly complete information from all participants was desired in order to properly evaluate performance of items and scales); (d) excessive identical consecutive responses; (e) evidence that the assessment was not completed in a single sitting (i.e., time to completion in excess of 24 hours; applies only to Parent and Teacher who completed the tests remotely); or (f) an excessively fast completion time (determined via analysis of the distribution of response time and outliers). Applying these data-cleaning criteria resulted in the removal of 15.3% of cases for Parent, 11.7% of cases for Teacher, and 19.1% of cases for Self-Report.