Outcomes based education "…starts with a clear specification of what students are to know, what they are to be able to do, and what attitudes or values they should be able to demonstrate at the end of the program" (Killen, 2005, p. 77). 
The outcomes based approach works best for tasks or knowledge that are easily measured, such as whether someone can drive a forklift, rather than other topics where it's more speculative or subjective and therefore harder to measure, such as whether someone is able to write good music. The obvious issue in this example is defining 'good'.

The focus with the outcomes based approach is on the trainee and on them successfully achieving a specified and (preferably) well-defined outcome. Therefore it is important for a systematic process to be followed, starting with a planning or analysis phase. What does the trainee need to learn? What knowledge, skills, or attitudes (KSA) are required? And depending on the education organisation developing the materials, who are the intended trainees? What knowledge or experience do they already have? Once these and other details are established, the learning outcomes can be written, or NZQA Unit Standards (US) selected that will meet the desired outcomes. 

NZQA US is a prime example of learning outcomes from which to develop a training programme. Although, while aligning training to NZQA units or qualifications is advantageous to help ensure consistency of training nationally, individual trainee's prior knowledge and skills aren't taken into account. In an ideal world, training and assessment would be tailored to each individual to take into account each trainee's experience, knowledge, skills, and cognitive abilities, but unfortunately that's not practical, especially on a national scale. Training packages must be developed carefully and delivered in such a way to prevent the effect of any weaknesses in the outcomes based approach. 

One other aspect of NZQA US is that although the learning outcomes are specified, how the trainee is to achieve the outcomes (such as suggested course duration or attendance numbers) is not. So it is up to training providers to determine what is appropriate, and include those considerations in the planning, design and development phases.

A limitation to the outcomes based approach is that a substantial amount of work is required for the planning, design and development of a training programme. However, if a training package is produced well and includes important components such as a Training Management Plan (TMP), lesson plans, assessments etc, it can be delivered time and time again by many trainers to many trainees, therefore justifying the original investment.

While utilising an outcomes based approach to education such as NZQA US provides well-defined outcomes or KSA for the trainees to achieve, the development of a training programme must be approached systematically in order to overcome a number of the weaknesses of this approach, allowing trainees the best opportunity to successfully achieve the desired learning outcomes.

References
Killen, R. (2005) Programming and Assessment for Quality Teaching and Learning. (pp. 65-100). Southbank Australia: Thomson.