A jack knife is a pocket knife that is put to many tasks, because it's ready to hand. Often there could be a better tool for the job, such as a screwdriver, a scraper, or a can-opener, but these are not usually pocket items. In statistical terms, the expression implies making do with what's available. Another simile, of an extreme situation, is…

Extreme-value statistics is often used to estimate so-called return values (actually related to quantiles) for environmental quantities like wind speed or wave height. A basic method for estimation is the method of block maxima which consists in partitioning observations in blocks, where maxima from each block could be considered independent.…

One of the issues facing educational research workers today is the determination of the similarities and differences between countries and cultures in the factors that influence educational outcomes. The author of this article proposes a new approach to this problem. Usually when countries are compared, the complete student samples are taken into…

This manual is a first effort to begin to identify, describe, and develop procedures for assessing various aspects of digital reference service. Its overall purpose is to improve the quality of digital reference services and assist librarians to design and implement better digital reference services. More specifically, its aim is to: assist…

This paper examines how various equating methods are affected by: (1) sampling error; (2) sample characteristics; and (3) characteristics of anchor test items. It reviews empirical studies that investigated the invariance of equating transformations, and it discusses empirical and simulation studies that focus on how the properties of anchor tests…