Google Attribution will allow advertisers to see whether online ad campaigns generate offline sales.
Announcing the service, Google said that it captures around 70% of credit and debit card transactions in the US.
Critics said it represented another blow to privacy.
Google announced the new product in a blogpost, saying: “For the first time, Google Attribution makes it possible for every marketer to measure the impact of their marketing across devices and cross-channel – all in one place.”
Google has vast amounts of data on net users, from services such as AdWords, Google Analytics and DoubleClick Search which combine details about the ads displayed on devices with what has been searched for in Google.
Google can also collect location information from phones, allowing it to work out when a user has seen an ad, and whether they have searched for the product advertised and gone to an offline shop to buy it.
It introduced store visit measurements back in 2014, using the location data on mobiles to track when people visited a store.
“In under three years, advertisers globally have measured over five billion store visits,” it said.
It added that Google’s “third-party partnerships” already capture approximately 70% of credit and debit card transactions in the US, but did not reveal who the partners were or how information was captured.
Google will not have access to the details about what individuals spend – instead they learn the value of all purchases in a certain time period.
The kinds of data that Google is collecting also could become an inviting target for hackers, said Miro Copic, a marketing professor at San Diego State University.
The Mountain View, Calif., company — a division of Alphabet Inc. — already runs the world’s biggest online ad network, one that raked in $79 billion in revenue last year. That puts it in the best position to capture any additional marketing dollars spent on computers and mobile devices.
Google unveiled the store-sales measurement tool Tuesday in San Francisco at an annual conference it hosts for its advertisers.
This meeting is an opportunity for Google not only to flaunt its new tools, but also to work on regaining ground with advertisers who have recently boycotted YouTube.
Major advertisers began pulling back two months ago over concerns that Google hadn’t prevented major brand advertising from appearing alongside extremist video clips promoting hate and violence.
Google says its computers rely primarily on log-in information, such as email addresses, to identify the people clicking on ads. It then matches that data with other identifying information compiled by merchants and the issuers of credit and debit cards to figure out when digital ads contribute to an offline purchase.
Google’s tool also doesn’t work for cash payments or the 30% of U.S. card transactions that Google can’t currently access.
Google gives its users the option to limit the company’s tracking and control what types of ads they are shown — although in practice, relatively few users tweak such settings.