Your medical records might be used for scientific research. But don’t worry, you’re told — personally identifying data were removed.

Information about you gathered by the Census Bureau might be made public. But don’t worry — it, too, has been “anonymized.”

On Tuesday, scientists showed that all this information may not be as anonymous as promised. The investigators developed a method to re-identify individuals from just bits of what were supposed to be anonymous data.

In most of the world, anonymous data are not considered personal data — the information can be shared and sold without violating privacy laws. Market researchers are willing to pay brokers for a huge array of data, from dating preferences to political leanings, household purchases to streaming favorites.