The firm has pushed ahead of its own original schedules for sample size increases, in response to client concerns that samples were unreliable, particularly for ethnic-minority audiences.

At the same time the firm has announced an increase in the minimum sample targets in the Memphis and Providence markets, and is continuing its work to increase the proportion of cellphone-only households in its panel – a particularly important area of focus as cell-onlys are more likely than others to be young and from ethnic minorities.

PPM is now the ratings currency in 25 of the country’s 300+ radio markets, with eight more set to make the switch before the end of the year.