Abstract
Project monitoring, impact evaluation, results-based management and effects assessment are all based on the comparison of observed changes in the project population with the situation prior to the launch of the project. However, a significant proportion of each of these types of estimation has to be made without access to baseline data on the project or control groups. This paper examines some of the reasons for this widespread lack of baseline data and describes and illustrates a range of techniques that can be used for the ‘reconstruction’ of baseline data.