The UK still does not have an accurate system for counting people in and out the country, BBC News reported yesterday.
In fact, BBC News says that migration figures are based on "the answers given by a sample of travellers who agree to be stopped and questioned by a team of social survey interviewers at Heathrow and other main air, sea and rail points of entry to the UK."
According to BBC News, the International Passenger Survey (IPS), designed in the early 1960s, uses around 240 officials stationed at major airports and ports around the country and they aim to interview every 30th or 40th passenger streaming through arrivals or departures.
In a single year, some 300,000 people are interviewed by IPS officials, which is said to represent just 0.2% of the 200 million who enter and leave the UK over the same period.
BBC News reports that experts say emigration statistics are particularly flawed, as IPS emigration estimates are based on interviews with just 2,000 people.
According to BBC News, the e-borders scheme will replace IPS, but it remains a "work in progress" and some fear it might stay that way, with 2018 being the earliest that any e-borders data could be incorporated in the figures.
While the government denies that the IPS is a faulty instrument for measuring its progress on migration, BBC News concludes that, for now, net migration statistics should continue to be taken with a major dose of salt.