Reviewing ministerial salaries: Seven lessons from the private sector by Mak Yuen Teen, Today

http://www.channelnewsasia.com/stories/singaporelocalnews/view/1131260/1/.html

Two, adopt some macro performance measures which capture overall performance in a holistic way (such as average GDP growth, average wage growth & unemployment rate) and micro performance measures which directly reflect a particular minister's performance (e.g. traffic accident rates, average expressway speeds, admission rates of S'poreans into local universities, percentage of low-income families owning HDB flats).