Level-Crossing Problems and Inverse Gaussian Distributions: Closed-Form Results and Approximations focusses on the inverse Gaussian approximation for the distribution of the first level-crossing time in a shifted compound renewal process framework. This approximation, whose name was coined by the author, is a successful competitor of the normal (or Cramér's), diffusion, and Teugels’ approximations, being a breakthrough in its conditions and accuracy. Since such approximations underlie numerous applications in risk theory, queueing theory, reliability theory, and mathematical theory of dams and inventories, this book is of interest not only to professional mathematicians, but also to physicists, engineers, and economists. People from industry with a theoretical background in level-crossing problems, e.g., from the insurance industry, can also benefit from reading this book. Features: Primarily aimed at researchers and postgraduates, but may be of interest to some professionals working in related fields, such as the insurance industry Suitable for advanced courses in Applied Probability and, as a supplementary reading, for basic courses in Applied Probability