NCHRP 20-45
Scientific Approaches
to Transportation Research
Scientific Approaches
to Transportation Research
|
|
NCHRP 20-45 Scientific Approaches to Transportation Research |
This CD contains on-line versions for Volumes 1 and 2 of this project. Both are in HTML and PDF format. The following sections are provided to help you quickly find the materials you are looking for:
|
Vol. 1 Summary - Overview of Volume 1 |
||
|
The purpose of Volume 1 is to improve the quality of transportation research. Emphasis is placed on applied research because this constitutes the dominant research activity in most transportation agencies. |
||
|
Vol. 1 Chapter 1 - Introduction |
||
|
This chapter offers an overview of rest of the manual, and a description of research, as well as a discussion of transportation research and ethical standards of research. |
||
|
Vol. 1 Chapter 2 - Principles of Scientific Inquiry |
||
|
This chapter provides a summary of the principles of scientific inquiry. The purpose of this chapter is to explain terminology and introduce basic concepts, which will be explained in more detail in later chapters. Much of the content has been based on explanations and examples given by Wilson (1). |
||
|
Vol. 1 Chapter 3 - The Research Process |
||
|
This chapter describes research as a systematic process, identifies the major activities associated with any research project, and describes the tasks associated with each activity. It also discusses client involvement in the research process, and some of the attributes of a successful researcher and research manager. |
||
|
Vol. 1 Chapter 4 - Data Collection and Management |
||
|
This chapter deals with questions that arise in data management beyond those related to data analysis. These questions arise at several points in the life of the project: before, during, and after data collection, after data analysis, and after the study is complete. |
||
|
Vol. 1 Chapter 5 - Reports and Presentations |
||
|
This chapter provides an overview of the content and issues involved in preparing reports, scientific papers, and oral presentations. Background information, format requirements, and examples are provided in Appendix C. |
||
|
Vol. 1 Appendix A - Literature Searches |
||
|
A review of the literature is an essential component of any research study. This appendix summarizes the sources of information and the strategies for identifying and obtaining relevant materials. Details on how to report a literature review and the format for citations are given in Appendix C. |
||
|
Vol. 1 Appendix B - The Research Process - Details and Examples |
||
|
The purpose of this appendix is to provide a more detailed description, and a number of examples, of some of the activities described in Chapter 3. Most of the sample documents have been taken from the National Cooperative Highway Research Program. These documents can be modified relatively easily to suit the requirements of other programs. |
||
|
Vol. 1 Appendix C - Writing and Format of Reports |
||
|
This appendix complements the contents of Chapter 5 by providing guidance relating to the writing of reports, particularly those for external publication or distribution. Most of the recommendations for format are taken from instructions prepared by the Transportation Research Board. In situations where the publisher (be it the research agency, a technical society, or a commercial publisher) has specific rules for style and format, these will obviously take precedence. Appendix C also describes types of figures used in reports and gives several examples. |
||
|
Vol. 1 Appendix D - Peer Review of Research |
||
|
The result of the review of a researcher's work by professional peers is a measure of the researcher's standing in the profession. Peer review is the process commonly used by publishers to determine whether technical and scientific papers are worthy of publication. This appendix describes briefly the process of peer review and the role of the reviewer, as well as including, as an example, the review forms used by the Transportation Research Board. |
||
|
Vol. 1 Appendix E - Checklist |
||
|
The manual presents a substantial amount of information on the conduct of research studies. This appendix contains a convenient checklist of the major steps that are essential to the completion of a successful research project. The objective in preparing the list was to identify the most important items in point form. The reader is referred to the text of the manual for a full explanation of individual items. |
||
|
Vol. 1 References - References |
||
|
This section contains a listing of the references used in Volume 1. |
||
|
Vol. 2 Summary - Summary of Volume 2 |
||
|
Volume 2 is intended to complement Volume 1. Volume 2 consists of six chapters and four appendices. The level of detail provided in the manual is sufficient for researchers and research managers to correctly select, apply, and interpret a variety of statistical techniques. For the vast majority of scientific investigations, the manual will provide the direction and guidance necessary to select and begin applying statistical modeling techniques. However, it cannot possibly contain sufficient detail to cover all the complexities of specific modeling approaches, experimental designs, and data management issues-and in these instances, supplemental references are identified. |
||
|
Vol. 2 Chapter 1 - Identification of Empirical Setting |
||
|
The purpose of identifying the empirical setting of research is so that the researcher or research manager can appropriately address the following issues: 1) Understanding the type of research to be conducted, and how it will affect the design of the research investigation, 2) Establishing clearly the goals and objectives of the research, and how these translate into testable research hypotheses, 3) Identifying the population from which inferences will be made and the limitations of the sample drawn for purposes of the investigation, 4) Understanding the type of data obtained in the investigation, and how this will affect the ensuing analyses, and 5) Understanding the limits of statistical inference based on the type of analyses and data being conducted, and how this will affect final study conclusions. |
||
|
Vol. 2 Chapter 2 - Data Management, Analysis Tools, and Analysis Mechanics |
||
|
This chapter explores different tools and techniques for handling data for research purposes. This chapter assumes that a research problem statement has been formulated, research hypotheses have been stated, data collection planning has been conducted, and data have been collected from various sources (see Volume 1 for information and details on these phases of research). This chapter discusses how to combine and manage data streams, and how to use data management tools to produce analytical results that are error free and reproducible, once useful data have been obtained to accomplish the overall research goals and objectives. |
||
|
Vol. 2 Chapter 3 - Identification of Appropriate Statistical Method |
||
|
The purpose of this chapter is to identify the appropriate statistical method(s) for analyzing a specific type of data. The chapter consists largely of flow charts to guide the analyst through a series of questions, eventually directing the analyst to the correct statistical method. |
||
|
Vol. 2 Chapter 4 - Continuous Dependent Variable Models |
||
|
This chapter presents several important statistical methods including Analysis of Variance, Linear Regression, Time Series Analysis, and Survival and Hazard Models. For each method, the text describes the purpose of the method, basic assumptions, inputs and outputs, application methodology, examples, trouble shooting, and additional references. |
||
|
Vol. 2 Chapter 5 - Discrete Dependent Variable Models |
||
|
Logit, Nested Logit, and Probit models are used to model a relationship between a dependent variable Y and one or more independent variables X. The dependent variable, Y, is a discrete variable that represents a choice, or category, from a set of mutually exclusive choices or categories. |
||
|
Vol. 2 Chapter 6 - Nonparametric Methods |
||
|
Nonparametric methods are uniquely useful for testing nominal (categorical) and ordinal (ordered) scaled data--situations where parametric tests are not generally available. An important second use is when an underlying assumption for a parametric method has been violated. In this case, the interval/ratio scale data can be easily transformed into ordinal scale data, and the counterpart nonparametric method can be used. |
||
|
Vol. 2 Appendix A - Glossary |
||
|
This appendix presents a glossary of useful statistical and research-related terms. |
||
|
Vol. 2 Appendix B - Useful Transformations |
||
|
Transformations are used to present data on a different scale. The nature of a transformation determines how the scale of the untransformed variable will be affected. In modeling and statistical applications, transformations are often used to improve the compatibility of the data with assumptions underlying a modeling process, to linearize the relation between two variables whose relationship is nonlinear, or to modify the range of values of a variable. Transformations can be done to dependent variables, independent variables, or both. |
||
|
Vol. 2 Appendix C - Statistical Tables |
||
|
This appendix contains relevant tables of statistical distributions and parameters. |
||
|
Vol. 2 Appendix D - References |
||
|
This appendix provides a list of references used in Volume 2, organized by topic. |
||