Chapter 1 - Introduction
Quality of data has many faces. Primarily, it has to be relevant (i.e.,
useful) to its users. Relevance is achieved through a series of steps starting
with a planning process that links user needs to data requirements. It continues
through acquisition of data that is accurate in measuring what it was
designed to measure and produced in a timely manner. Finally, the data
must be made accessible and easy to interpret for the users. In
a more global sense, data systems also need to be complete and comparable
(to both other data systems and to earlier versions). The creation of data that
address all of the facets of quality is a unified effort of all of the development
phases from the initial data system objectives, through system design, collection,
processing, and dissemination to the users. These sequential phases are like
links in a chain. The sufficiency of each phase must be maintained to achieve
relevance. This document is intended to help management and data system "owners"
achieve relevance through that sequential process.
1.1 Legislative Background
The 1991 Intermodal Surface Transportation Efficiency Act (ISTEA) created the
Bureau of Transportation Statistics (BTS) within the Department of Transportation
(DOT). Among other things, it made BTS responsible for: "issuing guidelines
for the collection of information by the Department of Transportation required
for statistics … in order to ensure that such information is accurate, reliable,
relevant, and in a form that permits systematic analysis." (49 U.S.C. 111
(c)(3))
A parallel requirement for developing guidelines emerged in the Paperwork Reduction
Act of 1995. It tasked the Office of Management and Budget (OMB) to "develop
and oversee the implementation of Government wide policy, principles, and guidelines
concerning statistical collection procedures and methods; statistical data classification;
statistical information presentation and dissemination; timely release of statistical
data; and such statistical data sources as may be required for the administration
of federal programs." (44 U.S.C. 3504 (e)(3))
Lastly, the Consolidated Appropriations Act of 2001, section 515, elaborated
on the Paperwork Reduction Act, requiring OMB to issue guidelines ensuring the
quality of disseminated information by 9/30/2001 and each federal agency to
issue guidelines by 9/30/2002.
1.2 OMB Guidelines for Ensuring Information Quality
On 28 September 2001, OMB published a notice in the Federal Register (finalized
as 67 FR 8452, February 22, 2002) that required agencies to issue guidelines
for ensuring and maximizing the quality of information disseminated by federal
agencies.
As defined in the OMB guidance, quality consists of:
- Utility, i.e., the usefulness of information to intended users,
- Objectivity in presentation and in substance, and
- Integrity, i.e., the protection of information from unauthorized access
or revision.
Agencies were required to develop guidelines, covering all information disseminated
on or after October 1, 2002, regardless of format. Agencies were also required
to develop a process for pre-dissemination review of information, an administrative
mechanism allowing the public to request correction of information not complying
with the guidelines, and an annual report to OMB indicating how the public requests
were handled by the mechanism.
These guidelines incorporate the statistical aspects of the OMB guidelines
as a baseline and elaborate on its recommendations to produce statistical guidelines
adapted for the Department of Transportation.
1.3 Applicability
These guidelines apply to all statistical information that is disseminated
on or after 1 October 2002 by agencies of the Department of Transportation (DOT)
to the public using the "dissemination" definition in the OMB guidelines.
That definition exempts a number of classes of information from these guidelines.
Major types of exempted information are listed below. A more detailed list is
provided in section IV of the DOT Information Dissemination Quality Guidelines,
of which this document is a subsection.
- Information disseminated to a limited group of people and not to the public
in general.
- Archival records that are inherently not "active."
- Materials that are part of an ad judicatory process.
- Hyperlinked information.
- Opinion offered by DOT staff in professional journals.
DOT disseminated data contain a lot of information provided by "third
party sources" like the states, industry organizations, and other federal
agencies. These guidelines apply to that disseminated data unless exempted for
other reasons discussed above. However, DOT guidelines indicating design, collection,
and processing methods do not apply to data acquisition steps performed by non-federal
sources. Steps performed by federal sources outside DOT before providing the
data to DOT will be governed by the agency’s own guidelines in accordance with
this legislation. For data provided to DOT by third party sources, these guidelines
primarily emphasize disseminating information about data quality, the DOT processing
methods, and analysis of the data provided to the users.
1.4 Types of DOT Statistical Data Collected
The recommendations within these guidelines apply to a wide range of data collection
types. They include reporting collections, surveys, and special studies.
Reporting collections are set up to be automatic delivery of data into the
data system. They collect incident information from government (federal, state,
or local) and industry sources and periodic information on transportation flow
and volume from government and industry. Incident data tend to cover all incidents
(e.g., fatal accidents), though some data may be sampled due to its sheer volume
(e.g., highway injuries). Flow and volume collections are a mixture of 100%
collection and sampled data. Surveys and special studies are more of an outreach
form of data collection. Surveys and studies are usually conducted using some
form of sampling.
Samples taken for any data collection may be selections of people or organizations
from lists, samples of geographic areas or sections of highway, or samples of
time segments.
1.5 Overview of the Statistical Guidelines
The quality guidelines for statistical information are based on structured
planning (section 2), sound statistical methods (sections 3 and 4) and the principle
of openness (sections 5 and 6). Structured planning maintains the link between
user needs and data system design. Sound statistical methods produce information
(data and analysis results) that conforms to that design. Openness ensures that
users of statistical information can easily access and interpret the information.
Each section begins with a statement of principles, which contain definitions,
assumptions, and rules or concepts governing action. The principles are
followed by guidelines, which are specific recommended actions with examples.
Finally, each section concludes with references.
1.6 Statistical Guidelines Relationship to DOT’s Information Dissemination
Quality Guidelines
These statistical guidelines are a subset of the DOT Information Dissemination
Quality Guidelines. Chapters 2 through 6 discussed above form section VI, paragraphs
a – e in that document.
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