Accurate estimates of development effort play an important role in the successful management of larger Web development projects. By applying measurement principles to measure qualities of the applications and their development processes, feedback can be obtained to help understand, control and improve products and processes. The objective of this paper is to present a Web design and authoring prediction model based on a set of metrics which were collected using a case study evaluation. The paper is organized into three parts: part I describes the case study evaluation (CSE) in which the metrics used in the prediction model were collected. These metrics were organized into five categories: effort metrics, structure metrics, complexity metrics, reuse metrics and size metrics. Part II presents the prediction model proposed, which was generated using a Generalised Linear Model (GLM), and assesses its prediction power. Finally, part III investigates the use of the GLM as a framework for risk management.