Datalogix, an analytics firm perhaps best known for examining the offline sales impact from ads on Facebook and Twitter, is buying shopper-marketing firm Spire Marketing.

Terms of the cash-and-stock deal, which closed late last week, weren't disclosed. The addition of Monroe, Conn.-based Spire brings the total workforce of San Francisco-based Datalogix to around 350, with sales "comfortably north of $100 million," said CEO Eric Roza.

Spire handles shopper analytics for 24 regional supermarket retailers who have a combined 30 million households in their loyalty-card database, or roughly a third of U.S. households. Because most of those retailers do little digital advertising now and tend to have an under-developed web presence compared to bigger players, Mr. Roza said he also sees potential to help them move more of their advertising into digital.

Mr. Roza also sees the Spire acquisition helping Datalogix move deeper into shopper marketing, where much of the digital ad buying in packaged goods takes place. Shopper-marketing or sales executives often control that portion of digital ad budgets for co-operative online display and search buys, including on retailers' own websites.

The 12-year-old Datalogix, which focuses both on digital-ad targeting based on prior purchase history and evaluating how digital ads affect purchase, has seen its sales boosted in recent years as Facebook and then Twitter went public and turned to the firm to help prove ads on their social networks work for deep-pocketed packaged-goods, retail and automotive clients.

"We're an arbiter and would argue the primary arbiter for a lot of brands on whether a digital campaign was successful and will be in the future," Mr. Roza said.

Datalogix already works with many specialty retailers such as apparel merchants, Mr. Roza said. "We think there's going to be some really interesting cross pollination, which no one really has tried to do, between mid-size speciality retailers and mid-size grocers, which are two groups of retailers who've had nothing to do with each other historically, but we think they share a lot in common."

Spire was founded in 2007 as Loyalty Marketing Analytics by Paul Taylor and Brian Ochs, two former executives with marketing analytics firm ImmediateFX, and later joined that same year by James Simon. The three will join other Spire employees at Datalogix as part of the acquisition, Mr. Roza said.