Since the rst shape-from-shading technique was developed by Horn in the early 1970s, diierent approaches have been continuously emerging in the past two decades. Some of them improve existing techniques , while others are completely new approaches. However, there is no literature on the comparison and performance analysis of these techniques. This is exactly what is addressed in this paper.

We study earnings mobility and instability using data from the Panel Study of Income Dynamics. Our main contribution is to update mobility and instability calculations to include data from the 1990s, although we also provide a number of tests of robustness across mobility and instability indicators and sample definition. All in all, we find few trends in earnings mobility and instability that p...

As Martin Campbell-Kelly [5] notes in his paper on this panel, data on the emergence of the software industry is sparse, and "In the absence of hard quantitative data, the best historical approach appears to be one based on case studies." While his paper provides case studies of specific software firms, this paper provides a different type of case study: a study of the emergence of application ...