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23 Software Data Checks are used during production for encompasses all the activities focusing on increasing the abil- quality control, when the data are submitted for qual- ity to fulfill requirements for the product of service being pro- ity acceptance, and when the data have been entered duced. The definition used in pavement engineering is closer into the pavement management database. Typical checks to the definition provided by the National Quality Institute, include network-level checks for ratings that are out of which defines quality assurance as "actions taken by the buyer expected ranges, checks for detecting missing segments or user of the data to ensure that the final product is in compli- or data elements, and statistical analyzes to check for ance with the agreements, provisions, or specifications." data inconsistencies. Other Tools: In addition to the test described earlier, Quality acceptance tools are used for testing both the pave- some agencies also conduct other tests, such as time- ment condition data that are collected by the agency and those history comparisons, geographic information system that are collected by a service provider. These tests validate (GIS)-based analysis, and verification of sample data that the data meet the establish requirements before they are by independent third parties. used to support pavement management decisions. Examples of commonly used quality activities include control/verification As previously discussed, the tools described can be included site testing, complete database checks (e.g., to check for rat- in the quality control plans, quality acceptance procedures, ings outside of an expected range), sampling and retesting and/or independent verification processes. For example, the for quality acceptance, GIS-based quality checks, and time- equipment calibration is a key component of the quality con- history comparisons. trol process, but the verification of this calibration is typically also included as part of the quality acceptance plans. Simi- Software programs used for quality management usually larly, control or verification test sites are used by most agen- search for data that are missing, misidentified, incorrect with cies for both quality control and acceptance. respect to segment size, improperly formatted, and/or outside of expected ranges. These programs ensure data complete- ness and functionality. For example, the state of Oklahoma QUALITY CONTROL uses a Microsoft Access-based program with Visual Basic modifications to perform such tasks (52). Use of such pro- Quality control includes actions and considerations necessary grams not only ensures completeness, but standardization as to assess and adjust production processes to obtain the desired well, reducing problems with time-history updates and allow- level of quality of pavement condition data. These activities ing for better analysis of raw data into higher-level data such include checks on the equipment used to collect the data, the as composite indices. personnel responsible for the data collection, and the data col- lection process itself. When data are being collected using auto- matic data collection equipment, quality control may include INDEPENDENT ASSURANCE equipment maintenance, testing, and calibration. Training and supervision of the survey crews is critical when data are col- Quality engineering practices typically recommend the inclu- lected using manual/visual surveys. Examples of quality con- sion of at least some degree of external audit in the quality trol activities also include data verification checks using control management plan; this is called independent assurance. The or verification sections, on-vehicle real-time data checks, peri- purpose of the independent assurance testing is to validate the odic diagnostics/data checks, submitted data and video checks, data for the user agency. Data checks by quality acceptance distress rating data checks, and database checks. personnel are intended to ensure the accuracy of the data. Such checks typically involve making sure that distresses are prop- Before data collection, equipment is to be properly cali- erly identified and severity is properly evaluated. The check brated, procedures clearly defined and documented, and per- can be done by the data collection personnel, by someone else sonnel trained. During data collection, it is important that internal to the organization, or by an external third party. For pavement condition data be continuously monitored by a vari- example, a procedure to verify the quality of the pavement data ety of possible methods to ensure equipment calibration and collection during production is the use of a sample of a "con- data accuracy and consistency during the collection effort. trol" section that is resurveyed or reanalyzed by an indepen- This monitoring allows for errors to be detected and cor- dent evaluator and the results compared with the production rected before submission of large batches of unsatisfactory ratings. The reference measurements on these sections are data. After data collection is complete, the data may then be determined using the best available practical technique for that validated before acceptance. particular pavement condition indicator. The survey showed that only 4% of the agencies use independent verification for quality control and 12% for quality acceptance. QUALITY ACCEPTANCE Quality acceptance activities are those that govern the accep- REFERENCE VALUES/GROUND TRUTH tance of the pavement condition data; this is often referred to as quality assurance in the pavement data collection terminol- The determination of the correct value for pavement condi- ogy. However, this latter term is not used in this synthesis tion data is a particularly challenging task that has received because quality assurance in the quality management literature significant attention. This reference value or "ground truth"