Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning. (Rich Cook) Introduction This book includes a companion computer program, NLOGIT/ACA, which will enable you to replicate, extend and explore the models that are discussed in the book using your own computer and the data set on which the examples are based. NLOGIT/ACA is a special version of NLOGIT, a major commercial package published by Econometric Software, Inc., which is used world-wide by discrete choice modellers in transport, economics, marketing, statistics, and all the social sciences (you might want to visit the company's website, www.NLOGIT.com). This chapter will describe how to install and use this program on your computer. There are relatively few steps involved, and getting started should take only a few minutes. About the software About NLOGIT NLOGIT is an extension of another very large, integrated econometrics package, LIMDEP, that is used world-wide by analysts of models for regression, discrete choice, sample selection, censored data, count data, models for panel data, etc. NLOGIT includes all of the capabilities of LIMDEP plus the package of estimators for models of multinomial choice, such as the multinomial logit (MNL), multinomial probit (MNP), nested logit, mixed logit and several others and, in addition, some tools for analyzing discrete choice models such as the model simulator described in chapters 11 and 12 in this book. About NLOGIT/ACA This version of NLOGIT is restricted to use with the data set that is provided on the website with the program and analyzed in the text.