On the accompanying CD-ROM, the Research Team has created a Microsoft Access database that contains information used during the critical review of each literature item considered during this project. The development of this database was essential to managing the large amounts of data and review information captured during the course of the project. Additional literature items can be added to this database, if desired.
Below is a screen capture of the actual database form that was approved by FHWA and developed by the Research Team.
Six rating factors were used to individually assess each literature item reviewed for this project. Each was assigned a 0-5 ranking based on the strength of how well each literature item addressed the variable. A "0" indicated that the particular variable was not applicable to that literature item. The rating factors used were:
Exogenous/Endogenous Variables. This category describes how comprehensively the research addresses variables that may affect the outcomes or conclusions contained in the article. For example, household income is an exogenous variable that affects travel behavior and should be controlled in studies of design elements.
Validity. Essentially, this category measures how well-constructed was the research. Validity also tests how well the conclusions match the data outputs from the research.
Portability. This category of measurement determines if the research can be used in other geographic locations with the same facility as it was applied in the particular case shown in the research. For example, those studies that looked at conditions that were peculiar to a specific geographic area received lower scores; those that drew their data from a larger, more diverse geographic area received higher scores. In a few of the out-of-country studies, some datasets would clearly not be readily available in a usable format in the U.S.
Air Quality. This measure ascertains how directly relevant the research is to the area of air quality. Many articles examined the relationships between travel behavior and land use (low score), but a few researchers went further by attempting to quantify the actual emissions changes from the land use scenario (higher score).
Data Needs. Not a measure of data quality, this category describes how demanding the data collection process would be if applied to another, similar case. Those studies that were data-intensive received a lower score, particularly those that required detailed investigations of travel diary data or large field data collection efforts.
Cost-Benefit. If the research attempted to measure how cost-effective a particular action was in the research, then it received a higher score in this category. There were very few articles that received non-zero scores in this category.