TABLE OF CONTENTS
Summary
The Combined Summary cubes serve the following purposes:
- For states where some agencies are submitting Summary and others NIBRS, the cubes provide a way to generate state-wide totals.
- For agencies that transition from Summary to NIBRS, the combined summary cubes show consistent data throughout history.
- For states that want to continue to report numbers in the same way they have traditionally (using Summary counting rules), they can use the Combined Summary cubes even when all agencies have transitioned to NIBRS.
NIBRS data is converted to Summary following the rules in the attached document: "Conversion of NIBRS Data to SRS Data.pdf".
Crime counts are different when counted as Summary versus being counted as NIBRS.
Total Count of Crimes
Summary counts crimes by agency and by month. The same can be done with NIBRS records, but the
total count of crimes for a given agency/month will be different in Summary because only certain
offenses are counted. If an incident doesn’t include one of the following offenses, it is not counted in
the Summary data:
- 09A - Murder and Nonnegligent Manslaughter
- 09B - Negligent Manslaughter
- 11A - Rape
- 120 - Robbery
- 13A - Aggravated Assault
- 220 - Burglary/Breaking & Entering
- 23A-23H - Larceny-theft
- 240 - Motor Vehicle Theft
- 200 - Arson
- 64A - Human Trafficking-Commercial Sex Acts
- 64B - Human Trafficking-Involuntary Servitude
Due to the hierarchy rule (see below), a given incident, with multiple offenses, will be counted only once
in Summary. By contrast, a victim may be counted more than once in NIBRS. Specifically, if a victim is
subjected to multiple crimes against person, they will only be counted once in the total count of crimes
for the agency/month, but if a victim is subjected to multiple crimes against property, each crime is
counted separately.
Count of Crimes by Offense Type
The count of specific crimes by offense type will be different between NIBRS and Summary data for the
following reasons.
Hierarchy Rule
In Summary, only one offense is counted per incident. The offense that is chosen is the one that is
highest on the list above. For example, if an incident contains one person murdered, and two persons
robbed, the incident will be counted as one murder and no robberies in Summary data.
Thus, you should expect to see lower counts in Summary than in NIBRS for the offenses that are lower
down on the hierarchy list.
Note that Arson and Human Trafficking are not included in the hierarchy rule and all crimes with this
offense code are counted in Summary as well.
Burglary Rule
In Summary, the number of premises entered is relevant when the location type is hotel/motel or a
rental storage facility. In NIBRS data, each burglary is only counted once. For this reason, it is normal to
see burglary numbers being higher in Summary than in NIBRS.
Also, note that, in Summary, attempts to commit burglary are separated out as a third category (i.e.
separate from the forcible/non-forcible groupings). When counting burglary in NIBRS, most often, the
attempted burglaries are included in the count.
Weapon Rule (for Aggravated Assault, Robbery)
In NIBRS, an offense may involve the use of multiple weapons. However, in Summary only the most
significant weapon is counted. The hierarchy is as follows:
- Firearm (for any weapon of type 11, 12, 13, 14, or 15)
- Knife or Cutting Instrument (for weapon type 20)
- Other Dangerous Weapon (for any weapon of type 30, 35, 50, 60, 65, 70, 80, 85, 90 or 95)
- Hands, Feet, Fists, etc (for any weapon of type 40 or 99)
Rape Rules
In Summary, Rape is counted in two different ways. The “historical” way is to count only NIBRS offense
11A. The “current” way is to count NIBRS offenses 11A, 11B and 11C together. In NIBRS, “Rape” is
simply offense 11A, although most reporting involves “Sex Offenses”, which includes 11A, 11B, 11C and
sometimes 11D.
Also, note that in Summary attempts to commit rape are split out and counted as a distinct line item.
Motor Vehicle Theft
For MVT, in both NIBRS and Summary, the number of vehicles stolen is captured for completed offenses
(and a count of just 1 for attempted offenses). In Summary data, MVT is further broken down into the
different types of vehicle stolen. When a NIBRS incident involves the theft of different types of motor
vehicle, a single count of the number of vehicles stolen is given. In this way, the total count in NIBRS and
Summary would be the same (subject to the hierarchy rule), but the breakdown by vehicle type is
unlikely to match between Summary and NIBRS.
Count of Clearances by Offense Type
For clearances, the count of crimes cleared follows the same general rules as the count of crimes. The
most significant difference is that in Summary the clearances are counted based on when the first arrest
(or exceptional clearance) took place. If an incident took place in 2022, but the first arrest on the
incident took place in 2023, the clearance will be counted in 2023, and not in 2022. Care should be
taken when counting NIBRS clearances to follow the same approach. (The NIBRS Agency Crime Overview
report, for example, counts clearances for the crimes that took place in the year, rather than the
clearances that were accomplished within that year.)
Useful link
- Motor Vehicle Theft Related Crimes