Data collection ranges from the individual in a library extracting information from statistics to a team of thousands carrying out a national census. This book covers the range of enquiry techniques from the case study to the census, but gives major emphasis to data collection by sample survey. The development of sampling theory is comparatively new and provides a logical conceptual framework by which estimates of the characteristics of a population can be inferred from the results of an examination of only a sample of that population. The authors look at the problems of non-sampling errors and discuss the practical aspects of carrying out a sample enquiry with regard to the special difficulties of conducting surveys in developing countries. This second edition updates the authors, detailed and practical discussion on the development of survey capabilities in developing countries. The material on sample surveys and survey design has been merged into one chapter; discussion of other methods of data collection has been expanded to include qualitative interviewing, participant observation and group interviews and applied farm studies. Students of development studies, government officials and statisticians, anyone involved in survey research in developing countries would benefit from this publication.