An industry oversight board has reinstated accreditation for Nielsen’s national TV ratings measurement, more than 18 months after it was suspended.

The Media Rating Council, which applies standards for audience measurement, on Monday said it was lifting the suspension after Nielsen addressed several issues related to undercounting viewers in the early part of the COVID-19 pandemic.

Nielsen has undertaken strong efforts to correct the issues that led to its loss of MRC accreditation 19 months ago and to restore key aspects of its panel performance,” said George W. Ivie, executive director and CEO of the council. “The MRC’s audit has shown these efforts have been successful, and as a result, our TV Committee and board agreed that accreditation should be reinstated.”

Ivie noted a Nielsen pledge to improve its estimates of broadband-only households in the company’s national TV sample, and “enhancing the disclosures it provides to users about the variability associated with its estimates of television viewing” as key factors in the reinstatement.

The lifting of the suspension doesn’t totally wipe Nielsen’s slate clean with the council: Accreditation of its local TV ratings product is still suspended, and other Nielsen offerings — including the Nielsen One initiative, which will offer cross-platform measurement — are still under audit.

The Media Rating Council suspended Nielsen’s accreditation in September 2021 after networks and advertisers complained that Nielsen had let its national sample degrade in the early months of the pandemic and hadn’t taken sufficient steps to fix those issues. The suspension opened a door for other analytics providers to gain a bigger foothold in the industry.