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Standardizing the Display of IBR Data:
Drug Offenses - Estimated Drug Quantity and Type of Drug Measurement

Data Collection

The Estimated Drug Quantity and Type of Drug Measurement data elements are captured in the Property segment.   According to the FBI Data Collection Guidelines, the Estimated Drug Quantity element should be used to indicate the quantity of drugs or narcotics seized in a drug case.  The Type of Drug Measurement element should be used to indicate the type of measurement used in quantifying the drugs or narcotics.   Therefore, these data elements should be completed only if:

  • offense is Drug/Narcotic Violations
  • type of property loss is Seized or None
  • property description is Drugs/Narcotics

If the substance was sent to a laboratory for analysis, and a response has not yet been received, then 'None' should be entered as the drug quantity and 'Not Reported' should be entered as the drug measurement.  The Property Segment should be updated with the true quantity once the information is known.  These data elements should not be used when drugs or narcotics are burned, stolen, etc., in connection with other offenses. 

In the Estimated Drug Quantity data element, up to three entries can be made and nine character spaces are available to enter the whole number of pounds, ounces, grams, etc.   Three additional character spaces are available to enter the decimal amount.   A decimal point must be entered to separate the whole and partial amounts.  Up to three entries can be made in the Type of Drug Measurement data element to match the entries for drug quantity.  Eleven entry types are available: 

GM Gram FO Fluid Ounce
KG Kilogram GL Gallon
OZ Ounce DU Dosage Unit/Items
LB Pound NP Number of Plants
ML Milliliter XX Not Reported
LT Liter

If more than three drugs are involved, the quantities and measurement type of the two most important, as determined by quantity, value, and deadliness, should be entered in the first two entries.  The third entry, corresponding to the Over 3 Drug Types entry, should be left blank.

When the XX 'Not Reported' entry is used due to a lack of measurable data from a lab, this must be updated when the information is received. 

Data Quality Issues

The type of measurement used should make sense based on the type of drug being measured.  For example, it is unlikely that marijuana would be measured in fluid ounces.  As the table below shows, a small percentage of property entries listing drugs as property measure marijuana in fluid measurements.

Number of Property Entries Percentage
Fluid Ounces 47 .02%
Gallon 18 .01%
Liter 22 .01%
Milliliter 25 .01%

This data quality check is also useful to verify that no measurements are entered when the 'X' Over 3 Drug Types code is used.  In the 2000 NIBRS data, no measurements were associated with this code.

The crosstabulation tables used in this example are too large to be displayed here.   If you would like to recreate this table using your data in SPSS, download the syntax file.  Combine the figures created in the three tables to get totals.  If you need assistance using this file, please contact JRSA.