More than 50% of US apps on the Google Play Store use app ads, according to a new study published on Wednesday.
The study, by the Health Analytics Laboratory at Columbia University, found that 51% of apps are currently in app ad rotation and nearly two-thirds are in the mobile app ecosystem.
“App advertising is a key way for apps to connect with consumers, and its impact on the health care delivery system has been well-documented,” the study authors write.
“But in this study, we have found that the majority of health apps currently on the market use app advertisements, with the exception of a few apps, which are predominantly for the personalization and tracking of health data.”
Google and its App Engine platform, which runs Android apps on Google’s Android mobile platform, have long been considered a source of data that can be used to target ads.
Google has argued that its platform is open to all apps, and that it is not responsible for the apps’ advertising practices.
However, Google has recently been criticized for its advertising practices, and in May it came under fire for advertising on its search results.
The Health Analytics Lab also examined the relationship between app ad pricing and app sales.
Researchers found that, on average, an app with an app ad price of $0.25 was twice as likely to sell as an app without an ad price.
The researchers also found that while most apps were able to sell over 50% more apps than non-app apps, app ad sales were negatively correlated to app app ratings.
App ad ratings were negatively associated with app app purchases, with positive correlations to app reviews and app downloads.
While the study only looked at app ad prices, other research has shown that apps often use app ad revenue to improve their app experience and increase ad revenue.
For instance, an analysis from App Annie found that app ad revenues for the top 200 apps in the US accounted for roughly two-fifths of their total revenue in 2016.
Google and the app industry have also faced criticism for failing to adhere to guidelines that govern app monetization.
In April, the Food and Drug Administration fined Google $2.9 million for failing a series of inspections in the last three years, saying the company failed to adhere the guidelines it was required to by law.
As part of its response, Google launched a new app audit tool, called AdWords, that provides developers with tools to better monitor app ad performance.