Appendix D: Table Methodology

Table Data Used Construction 1 US Census and UCR - 2 NIBRS Administrative, Offense,
Offender, and Arrestee Segments ORI and incident numbers were selected in the offense segment where offense location = “school/college.” These ORI and incident numbers act as unique
identifiers and were matched to the other segments in order to count the selected table fields. The numbers reflect the number of records for each category. 3 NIBRS Offender Segment Offender ages were collapsed into the given age groups. Each number reflects the number of offenders reported. Offenders were only counted once in the table. 4 NIBRS Offender Segment Offender genders are selected by NIBRS gender code. Offenders were only counted once in the table. 5 NIBRS Offender Segment Offender races are selected by NIBRS race code. Offenders were only counted once
in the table. 6
NIBRS Victim Segment Victim-to-offender relationships are determined by victim segment data elements.NIBRS collects relationship information for up to 10 offenders for each victim.
The numbers reflected indicate the number of relationships (not just the number of victims or offenders). For example, an incident with 3 victims and 3 offenders involves 6 people but 9 relationships. 7 NIBRS Administrative Segment The numbers in the table are the number of incidents and report dates associated with school locations by month and year. On some occasions, the date of the
incident is unknown to law enforcement. For example, a school principal notices vandalism at the school on Monday morning and reports the crime. Though the
principal knows the vandalism did not occur before Friday afternoon, neither he nor law enforcement can determine whether it happened Friday evening, Saturday, Sunday, or early Monday morning. Therefore, law enforcement reports the earliest date in which the incident could have occurred (Friday) as the date of the incident.
In other instances, a crime occurs during a holiday or summer break and is not discovered and reported until the start of school or after the change of a month.
Law enforcement enters the date of the report as the date of the incident, potentially counting the incident in a different month than when it occurred. In this study,
incidents in which the dates of reports were used accounted for 19.5 percent of the incidents reported as having occurred in school locations. However, the percentages by month for the dates of reports and the actual dates of incidents are very similar (within 0.5 percent for each month), which indicates that only a small percentage of incidents may have occurred in prior months. 8 NIBRS Offense Segment The numbers in the table count the various entries reported for type weapon/force involved within an incident. Though each offense may have up to three types, the
table does not count the number of weapons. For example, if three shotguns were
used in an incident, the reporting officer records one weapon/force used type for shotgun. In addition, offense records with multiple weapon/force involved types are
counted more than once in the table. 9 NIBRS Offense Segment This table shows the number of offense records reporting the use of alcohol, computer equipment, and/or drugs by any of the offenders. As offenders may have used more than one type in an offense, the table does not reflect a count of offenders. 10 NIBRS Arrestee Segment Numbers in the table count the number of arrestees based on the UCR Arrest Offense Code found in the arrestee segment. Each arrestee is counted only once in
the table. 11 NIBRS Arrestee Segment Arrestee ages were collapsed into groups. The table numbers equal the total number of arrestees reported. Each arrestee is counted only once in the table. 12 NIBRS Arrestee Segment The table numbers equal the total number of arrestees as reported by gender. Each arrestee is counted only once in the table. 13 NIBRS Arrestee Segment The table numbers equal the total number of arrestees as reported by race. Each arrestee is counted only once in the table. 14 NIBRS Arrestee Segment The table numbers equal the total number of arrestees as reported by ethnicity. Each arrestee is counted only once in the table. Arrestee ethnicity is an optional NIBRS
field. 15 NIBRS Arrestee Segment The table numbers equal the total number of arrestees as reported by resident status. Each arrestee is counted only once in the table. Arrestee resident status is an
optional NIBRS field. A
NIBRS Offense and Victim
Segments The table counts the number of offenses for each offense type by year. Crimes against persons count one offense for each victim which is determined by the victim
segment Victim Connected to UCR Offense Code(s) data element and can link up to 10 offense codes to the victim. Both crimes against property and society count only one offense per distinct operation which is determined by the offense segment. B NIBRS Offense Segment This table has a unique unit of count. It is the number of weapon types found in offense records. Therefore, the table can be read as “there were 86,312 personal
weapon types associated with simple assault offense records.” However, it can also be read as “there were 86,312 simple assault records associated with personal
weapons.” This table does not count one offense for each victim of crimes against persons and only includes offense types for which weapon type is collected.