Welsh tax power scrutiny 'needs better economic data'
Tax powers should not be devolved to Wales until the right data is available to measure its economic performance, a leading academic has told BBC Wales.
Professor Max Munday's comments follow the concerns of AMs on the enterprise and business committee.
They said more statistics were needed to allow them to scrutinise the Welsh economy and performance of ministers.
The Welsh government said statisticians had been asked to consider what information could be produced.
In his Autumn Statement UK Chancellor George Osborne confirmed that business rates would be devolved to Wales.
Landfill tax, stamp duty and the power to vary rates of income tax are also due to be transferred when the Wales Bill going through Parliament becomes law.
That could give Wales control of up to £3bn worth of taxes a year, according to the Office for Budget Responsibility.
Speaking to the BBC's Sunday Politics Wales programme, Prof Munday of the Welsh Economy Research Unit said there were "gaps that need filling" in the economic information currently available.
"As more decision-making power is devolved to the Welsh government - particularly in terms of things such as taxes - there is a requirement for government ministers to have far more information on which to make informed decisions," he said.
"We need to build a stock of economic data now because we need time for this data to inform models and make for better decision-making," he added.
Inward investment, exports and business support were areas where better data was needed, according to a report by the assembly's enterprise and business committee.
Chairman William Graham said: "We want some indication to say exactly what the government is doing so the committee can properly scrutinise the minister and where necessary provide support."
The Welsh government said it accepted some of the committee's recommendations to make more data available but rejected others, some on grounds of commercial confidentiality.
It said it "recognises the potential value of improved export statistics" and said it had already asked statisticians to consider what information might be produced in the future to "enhance our understanding of the Welsh economy".