Revisit parameterization question

Dear All, I am working on a data set that the estimates become quite different under different model assumptions (such as fixed or not fixed ka, different block structure) using ADVAN4 TRANS1. One suggests me that I should use TRANS4 to avoid the problem of the high correlations among ka, Cl, V, k, and k12. When I reviewed the previous NM user discussion in "reparameterization", the highest "scored" discussion occurred in 2001. I am wondering whether there are any updated discussion and references on this topic. Any of your help are greatly appreciated. All the best Kuenhi Tsai Notice: This e-mail message, together with any attachments, contains information of Merck & Co., Inc. (One Merck Drive, Whitehouse Station, New Jersey, USA 08889), and/or its affiliates (which may be known outside the United States as Merck Frosst, Merck Sharp & Dohme or MSD and in Japan, as Banyu - direct contact information for affiliates is available at http://www.merck.com/contact/contacts.html) that may be confidential, proprietary copyrighted and/or legally privileged. It is intended solely for the use of the individual or entity named on this message. If you are not the intended recipient, and have received this message in error, please notify us immediately by reply e-mail and then delete it from your system.