The Land Transport Authority (LTA) has adopted a new method of tallying rail disruption numbers which excludes those caused by "external factors".
Not unexpectedly, figures collated with this new method are noticeably lower than previously.
For instance, under the old calculation, there were 12 major breakdowns (those longer than 30 minutes) last year. Under the new system, there were 10.
In the first nine months of this year, the authority said, there were seven such disruptions while, with the previous method, there would have already been seven in the first six months.
The LTA did not provide third-quarter figures under the previous method but, according to The Straits Times archives, there were at least three major breakdowns from July to September, including an unprecedented one that disabled the entire North-South and East-West lines on July 7.
The authority said the new method of counting disruptions excludes "factors beyond the control of the operators and LTA, such as passenger action". For instance, if a commuter's foot gets stuck in the gap between the train and station platform, or when someone trespasses onto a track.
In the first three quarters, "about 15 per cent" of disruptions longer than five minutes were caused by these factors, the LTA said yesterday.
For delays of more than five minutes, the LTA will also report the "mean distance travelled between delays" instead of the number of delays per 100,000km.
Again, the new method casts a rosier tint on the system's performance. Up to the end of September, the mean distance travelled between incidents was 149,000km - a 157 per cent improvement over the 58,000km clocked in 2011.
But with the previous method, the improvement was 53 per cent - from 1.75 delays per 100,000km to 0.83 in the first half of this year.
The LTA said that the Hong Kong Mass Transit Railway and the New York City Transit use a similar methodology.
It added that switching to the new method allows it to better measure the progress made by operators and regulator in improving reliability and "to facilitate international benchmarking".
Dr Walter Theseira, an economist at SIM University, said: "While I agree with the principle of making our rail reliability statistics comparable internationally, for commuters, a disruption is a disruption, regardless of cause.
"Some types of passenger action which contribute to delays can be reduced by revising the design of stations and trains."
Dr Theseira also noted that, while the overall statistics are improving, delays lasting more than 30 minutes "have not budged significantly in recent years, even with the revised methodology".
He added that these disruptions are the ones that cause the most inconvenience to the public.
"While service can be recovered readily for disruptions of a few minutes, major disruptions force commuters to travel by alternative modes of transport, and we don't have the capacity in the rest of the transport system to accommodate such a large volume of commuters readily during peak-hour major disruptions."