Biased figures on MRT breakdown rate

I was taken aback by Transport Minister Khaw Boon Wan's statement that the MRT is three times more reliable now than it was in 2015 (Khaw raises bar on MRT reliability; July 28).

However, after a more careful reading of the report, I realised that this conclusion was drawn from statistics that excluded delays caused by the new signalling system on the North-South Line.

Computing statistics this way is biased and unscientific.

I propose that delays caused by the testing of the new signalling system be factored in when calculating the mean kilometres between failures (MKBF).

If there has been a decrease in MKBF since 2015, this can be duly explained by the delays caused by the tests.

Calculating MKBF this way would give us a gauge as to how disruptive the tests of the new signalling system have been.

I support The Straits Times' coverage of the recent breakdowns and delays of the MRT (Minister takes aim at press; July 28).

If these disruptions remain largely unreported or are glossed over by the newspaper, it could hurt its reputation and relevance as a news source.

Chan Yeow Chuan

A version of this article appeared in the print edition of The Straits Times on July 29, 2017, with the headline 'Biased figures on MRT breakdown rate'. Print Edition | Subscribe