Professor James Brown made the statement as National Records of Scotland (NRS) prepares to progress to its coverage survey – the next stage of the country’s census.
The exercise is a separate survey from the census, conducted door-to-door at about 1.5 per cent of households to ensure an accurate picture of return rates has been recorded.
NRS is reporting a return rate of 87.5 per cent, or around 2,284,582 households.
Five of Scotland’s 32 local authorities have seen rates exceeding 90 per cent, while 28 reported 85 per cent or higher.
It comes as a second ‘unofficial’ extension to the census deadline was granted, with people now having been given until June 12 to avoid the threat of a £1,000 fine and complete the survey.
Prof Brown, who is leading a group of international authorities in providing external advice on the quality of the census, said the extension to Scotland’s completion deadline had improved consistency and returns across the country.
A low response rate at the time of the original deadline prompted the decision to extend the period for returns to the end of May.
Prof Brown said: “While the overall return rates are lower than originally planned, NRS’s extension has improved consistency and returns across the country.
“With this solid foundation, it is now time to move to the next phase and conduct a high-quality coverage survey.
“The coverage survey, combined with innovative use of administrative data, will allow NRS to estimate the size, shape and characteristics of the population as planned.
“The statistical methods for this are designed to be robust in a range of scenarios..”
Paul Lowe, NRS chief executive and Registrar General for Scotland, said he was “pleased” the steering group reported a “strong position to move forward”.
Mr Lowe said: “I welcome the contributions they will make to steering our statistical and methodological work over the next few months.
“This will support us to deliver our census coverage survey and our work to identify the appropriate administrative data, which can support our quality assurance work.”