After creating career ladders for sectors such as retail and cleaning, the labour movement wants to do so for "knowledge workers" too.

These are workers whose jobs deal with ideas and information, not physical labour.

The progressive wage model aims to help workers become more skilled and productive, so that they can move up into better jobs and earn more.

For low-wage jobs, labour- saving devices are the key driver of productivity, NTUC secretary- general Lim Swee Say told The Straits Times last week.

But for knowledge-based jobs, the approach is different. "We are now working with organisations that have expertise, not in supplying labour-saving equipment, but in managing human resources."

These organisations will help NTUC come up with a progressive wage model for knowledge workers, with an eye to boosting productivity in the "more advanced economy".

The employers to which the model will be presented are "knowledge-based organisations managing a world-class knowledge-based workforce," said Mr Lim. He did not give examples of what sort of jobs he had in mind, but said details would be available in a few months.

Besides helping highly educated workers get more productive, the labour movement also wants to help workers with limited education earn more.

Such workers might be stuck in their current salary scale because moving up requires better educational qualifications.

However, whether a worker can advance from one salary scale to another should depend on his productivity and skills, said Mr Lim. "Therefore, we should look more at their competencies rather than just qualifications alone."

NTUC thus intends to work with the Singapore Workforce Development Agency (WDA) to come up with a progressive wage model that ties career advancement to training qualifications, instead of academic ones.

To create this "qualifications ladder", NTUC plans to draw on the Workforce Skills Qualifications framework.

Under this national training framework, workers gain qualifications ranging from a certificate to an advanced diploma. Even if they do not get a full qualification, they get a statement of attainment for each module they complete, in a "bite-sized" approach.

"We are going to work even closer with WDA to see how can we roll out this qualification ladder, which is competency- based, skill-based, across more and more job sectors," said Mr Lim.