Comparing TMMi and TPI, which is not a valid reason for choosing either TPI or...

If the scope of test performance improvement covers all test levels, TMMi is preferred since TPI focusses mainly on black-box testing.

If the organization is already applying CMMI, TMMi may be preferred since it has the same structure and uses the same terminology. TMMi addresses management commitment very strongly and is therefore more suitable to support a top-down improvement process.

TPI is much more a bottom-up model that is suitable for addressing test topics for a specific (test) project.

TMMi can only be used with the traditional V model,whereas TPI can be used with all types of software life cycles.