Aggregation in Data Tables - Implications for Evaluating Criminal Justice Statistics (From Confirmatory and Exploratory Analysis of the Spatio and Temporal Properties of Crime Data, P 22-57, 1981, by Reginald G Golledge and Lawrence J Hubert - See NCJ-78709)

• NCJ Number: 78710
• Author(s): L J Hubert; R G Golledge; C M Costanzo; T Kenney
• Date Published: 1981
• Length: 36 pages
• Grant Number(s): 79-NI-AX-0057; SOC-77-28227
• Sponsoring Agency: National Science Foundation; National Institute of Justice (NIJ); US Dept of Justice NIJ Pub
• Corporate Author: University of California, Santa Barbara
• Publication Format: Document
• Publication Type: Statistics
• Language: English
• Country: United States of America
• Note: Available on microfiche from NCJRS as NCJ-78709.

Annotation

Implications of aggregation in data tables for evaluating criminal justice statistics are dicussed.

Abstract

Data collected on a set of objectors (e.g., cities) over a set of attributes (e.g., time points) can be subjected to a variety of aggregation schemes. In the study's first example of two aggregation schemes, a rank transformation was used within each row and on the rank sums for each column. This process ensures that each object or row contributes equally, so that some degree of natural comparability exists between the summary statistics of the two aggregation schemes. To develop more explicit relationships in terms of formulas, however, the transformations used in most of the study were based on obtaining z-scores. Observations within rows were aligned for location and scale. This convention allowed precise connections to be developed between the two aggregation schemes in terms of summary indices and z-statistics. Matrix extensions offer flexibility in defining different relationships among the attributes, but the problem of defining a transformation on the aggregate data matrix makes it difficult to develop precise formulas for connecting the two aggregation schemes. The methods of data aggregation discussed represent both ongoing procedures used in geography for aggregating data and alternatives to those standard procedures. The two-group discussion is concerned with the concordance between two classes, even though the various summary indices were subject to modification by the degree of internal concordance. Tabular data and 15 reference listings are provided, and definitions are appended. (Author summary modified)