Sample Overview

Introductory Note

In analyzing the programs that are the focus of this survey, a color coded system is used to highlight particularly noteworthy design features. This system is as follows:

Any design feature that appears to have been particularly effective based on (a) empirical evidence and/or (b) a widely accepted consensus will be underlined in green.

Any design feature that is interesting and may be particularly effective or ineffective, but for which there is insufficient evidence for an evaluation will be underlined in yellow.

Any design feature that appears to have been particularly ineffective based on (a) empirical evidence, (b) a widely accepted consensus, and/or (c) a subsequent decision by the designers to significantly alter the feature will be underlined in red.