Dear ACBC User,

A bug has been discovered in ACBC (Adaptive CBC) analysis.

The bug only affects ACBC studies that:

• Are analyzed in version 8.0 or later
• Use a constructed list for the attribute list
• Have one or more attributes with the "Include in BYO" option set to "No"

The problem affects proper utility calculations and also design information in an exported .cho file. BYO data recorded in the data file are not being read correctly during ACBC analysis. As a result, an incorrect design for the BYO question is used for utility estimation or exported to the .cho file.

The bug only affects studies that use a constructed list for the attribute list (even if use of the constructed list was only for attribute randomization). Use of a constructed list for a level list will not cause this problem.

We're sorry for this issue, and hope it didn't occur for any of your studies. If you have questions regarding your ACBC analysis, or how to check for or remedy the problem, please call us.

We are working on a fix to the problem, which will be available in version 8.1.2. We will notify you as soon as it is available.

We encourage you to forward this email to ACBC version 8 users in your organization.

Sincerely,

Sawtooth Software
(801) 477-4700