DURHAM URBAN OBSERVATORY REPORT - ASSISTANCE IN PUBLIC ADMINISTRATION DECISIONS - IMPLEMENTATION OF DIGITIZED LOCATION CHARACTERS IN THE MANAGEMENT DATA FILE OF THE DURHAM PUBLIC SAFETY PROGRAM - PART 2

• NCJ Number: 45516
• Author(s): B B BALFOUR; J S ROTHENBERG
• Date Published: 1976
• Length: 33 pages
• Corporate Author: Durham Urban Observatory; North Carolina Central University
• Sale Source: National Institute of Justice/
• Publication Type: Program/Project Evaluation
• Language: English
• Country: United States of America
• Note: SEE ALSO NCJ-45515 AND NCJ-45517

Annotation

AN EXISTING COMPUTERIZED MAP IS EVALUATED AS A VEHICLE FOR CONVERTING THE ADDRESS IDENTIFICATION OF CRIME INCIDENTS TO GEO-CODES WHICH IDENTIFY THE LOCATION OF INCIDENTS IN A COORDINATE SYSTEM.

Abstract

THE EVALUATION OF THE EXISTING FILE USED IN NORTH CAROLINA CONSISTED OF: (1) MATCHING THE ADDRESSES OF RECORDED PUBLIC SAFETY INCIDENTS DURING JULY 1975 WITH AN ADDRESS RANGE OF THE FILE TO OBTAIN COORDINATE GEO-CODES FOR THE RECORDED INCIDENT; (2) EVALUATION OF THE ACCURACY OF THE ASSIGNMENT OF COORDINATES; AND (3) ENUMERATION OF THE SHORTCOMINGS OF THE EXISTING FILE AS A VEHICLE FOR OBTAINING COORDINATE GEO-CODES FOR RECORDED PUBLIC SAFETY INCIDENTS. EIGHTY-SIX PERCENT OF THE RECORDED INCIDENTS FOR THE MONTH OF JULY 1975 WERE ASSIGNED COORDINATES USING THE EXISTING FILE. THE ASSIGNED COORDINATES ARE THE NORTH CAROLINA STATE PLANES COORDINATES. EVALUATION OF THE ACCURACY OF THE ASSIGNMENT OF COORDINATES WAS BASED ON SITE VISITS OF A SAMPLE OF THE RECORDED INCIDENTS. THE SITE VISITS DETERMINED THE CORRECT PLACEMENT OF THE INCIDENT AND ALLOWED FOR A CORRECTED ASSIGNMENT OF COORDINATES. BASED ON THIS SAMPLE, COORDINATES CAN BE ASSIGNED TO ENTRIES WITH AN AVERAGE ERROR OF 54 FEET FROM THE CORRECTED COORDINATES USING THE FILE. SHORTCOMINGS OF THE FILE AS A VEHICLE FOR ASSIGNING COORDINATE GEO-CODES INCLUDE FAILURE OF THE FILE TO COVER ALL OF THE AREA SERVED BY THE PUBLIC SAFETY NETWORK AND DIVERGENCE OF THE ADDRESS RANGE OF THE FILE FROM THE ACTUAL ADDRESSES IN THE STREET SEGMENT. NINETY-SIX PERCENT OF THE SEGMENTS HAD ADDRESSES DIFFERENT FROM THOSE IN THE FILE. IMPROVEMENT BEYOND THIS LEVEL OF ACCURACY WILL REQUIRE THE DEVELOPMENT OF A NEW COMPUTER MAP OR A REWORKING OF THE EXISTING FILE. USES OF COORDINATE GEO-CODES WAS DEMONSTRATED BY RECREATING THE GRID-CELL SYSTEM PRESENTLY USED TO SUMMARIZE PUBLIC SAFETY INCIDENTS. A COMPARISON OF THE MAPPING FROM THE DIGITIZED DATA WITH ONE FROM MAP REFERENCES OF THE RECORDED PUBLIC SAFETY INCIDENTS WAS MADE. MAPPING FROM COORDINATE GEO-CODED DATA WAS FOUND TO BE MORE EFFECTIVE THAN MAPPING FROM MAP REFERENCES IN THE FOLLOWING WAYS: (1) THE DIGITIZED MAPPING GAVE MORE ACCURACY THAN THE MAPPING BY MAP REFERENCES; (2) THE MAP REFERENCES DO NOT NEED TO BE ENTERED IN THE RECORDS OF THE INCIDENTS; AND (3) THE USE OF DIGITIZED DATA GIVES GREATER FLEXIBILITY FOR MAPPINGS, WHICH IS USEFUL IN A MANAGEMENT INFORMATION SYSTEM. (AUTHOR ABSTRACT MODIFIED--RCB)