HC Deb 19 July 2002 vol 389 c572W
Mrs. May

To ask the Secretary of State for Transport if he will make a statement on the methodology used by the SRA in order to seasonally adjust passenger kilometres. [71063]

Mr. Jamieson

[holding answer 18 July 2002]: Passenger Kilometres data are collected in four-weekly periods and are susceptible to seasonal effects. The SRA seasonally adjusts the four weekly data using a variant of the "X11 Arima" package, developed by Statistics Canada and used (and recommended) by the Office for National Statistics.

The SRA publishes both seasonally adjusted and unadjusted figures.