Marketing attribution company MarketShare of Westwood has raised an $8 million investment round to finance its April purchase of fellow marketing attribution company DataSong.

The investment was disclosed in documents filed with the Securities and Exchange Commission on Monday and came from prior investors, said MarketShare Chief Executive Wes Nichols.

Terms of the DataSong acquisition were not disclosed.

Since its founding in 2005, MarketShare has kept up with the marketing attribution industry via more than $84 million in funding and a willingness to acquire competitors.

“DataSong was our third acquisition and I know there will be more,” said Nichols.

Increased interest in improving the effectiveness of advertising campaigns has made marketing attribution, the use of software and statistical methods to link marketing campaigns to actual sales, a rapidly growing industry.

DataSong’s expertise in helping retail brands understand the individual purchase path of customers was especially prized, Nichols said.

“We are very quickly moving to an era where we could do analytics and attribution on an individual basis,” he said. “The methods that companies were using a couple of years ago are likely out of date, so we have to keep innovating for clients.”

Technology reporter Garrett Reim can be reached at [email protected]. Follow him on Twitter @garrettreim for the latest in L.A. tech news.