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2/22/96 Chapter 15 Coordinating Center page 15-9
that escape detection by the Coordinating Center from errors that were introduced in
data entry.
Each form type is a different file where the file name consists of the batch
number and form code.
Batch editing of data files consists of three phases beginning with a check for
consistency of form type within a file and the number of pages for each form. The
second phase of editing consists of core edits that are conducted for all forms. These edit
checks include identification of missing values, out-of-range values, illegal characters,
verifying correction of patient identification numbers, certifications, and visit windows.
Form specific edits consist of edits that are unique to that form type.
Errors in the data are reported by issuing an edit report that is mailed to the
Clinic. The edit report states the patient identification number, visit date, and form type,
and the item number and type of error for each problem detected, i.e., missing value,
range check, illegal character, etc. An edit report also is issued for forms that pass all
edits without errors. Computer-generated flags are attached to records for form with
errors to document the status of the record. Records with errors or questionable items
are marked as such and remain in a temporary file until final correction and
verification. Records that pass editing are transferred to the master database on a
regular basis.
15.8 Data Management
The SAS system is used for virtually all of the computer processing within the
Coordinating Center. We have considerable experience with SAS on a variety of
hardware platforms and have contributed to the development of SAS to meet the needs
of the Coordinating Center (Miller, 1977; Roesti et. al., 1984; Achtenberg, 1989). The use
of only a single integrated software system provides better utilization of the
Coordinating Center and Clinic manpower. The use of SAS also allows the use of a
single software system across a broad spectrum of hardware platforms.
Over the course of the CLEK Study, significant changes will occur in the
cost/performance curves for computers. SAS’s flexibility across hardware platforms
allows a balance between the stability of existing hardware systems with the economies
of newly available hardware. All Coordinating Center staff have a PC available for their
use with necessary SAS software. In addition, all of the PCs are connected to the
Division of Biostatistics’ UNIX machines, and to the university-wide ethernet for rapid
and reliable file transfer, for the receipt of electronic mail, and for connecting to other
computers for the execution of those SAS tasks which require a shared use computer.
In the CLEK Study database, all instances of each type of form are grouped
together as a single SAS dataset cross-indexed by patient ID. The entire collection of