Since April 2001, BCS interviews had been carried out on a continuous basis and detailed results from that point are now reported by financial years.Since 1994 there has been a separate Northern Ireland Crime Survey, on a biennial basis from 2001, and continuously from January 2005.It also provides a better measure of trends over time since it has adopted a consistent methodology and is unaffected by changes in reporting or recording practices.Professor Ken Pease, former acting head of the Home Office's police research group, and Professor Graham Farrell of Loughborough University, estimated in 2007 that the survey was underreporting crime by about 3 million incidents per year due to its practice of arbitrarily capping the number of repeated incidents that could be reported in a given year at five.[10] The ONS responded by explaining that because victims of ongoing abuse often are unable to recall the detail and number of specific incidents it makes sense to record this crime as a series of repeat victimisation.