Metaphone » Learn More


You are invited to participate in a research study about the privacy properties of telephone call and text message logs. You may be provided an optional opportunity to view a set of inferences about your own logs, including estimated interconnectivity with other phone subscribers and particular phone numbers of interest. You will not be identified in published results unless you provide your express permission. You will also not be contacted by researchers unless you provide your express permission.


The purpose of this study is to understand how much information can be inferred from such logs, with respect to the interconnectivity of phone subscribers, as well as individual activities, traits, and relationships.


In the course of the study, your mobile phone will transmit device logs and social network information to researchers at Stanford University. Device data will include records about your recent calls and text messages, such as Caller ID, time, and length. Social network data will include your profile, connections with other social network users (e.g. your “friends list”), and recent labeled activity (e.g. companions and places). Neither the device nor social network data will include the contents of any communication. Publicly available sources, such as Yelp, will be used to supplement collected data.


The data will be stored and analyzed at Stanford, then deleted at the end of the study. Completion is estimated for June 2014. Research staff will take reasonable precautions to secure the data in transit, storage, analysis, and destruction.


Time Involvement

Your participation is expected to take under five minutes.


Risks and Benefits

While we will take reasonable precautions to secure the data that you provide, there does remain a risk of inadvertent disclosure. We anticipate the benefits from this study to include informing policymakers and the public about the privacy properties of telephone metadata. We cannot and do not guarantee or promise that you will receive any benefits from this study. Your decision whether or not to participate in this study will not affect your employment, medical care, or grades in school.



You will not receive payment for your participation.


Participant’s Rights

Your participation in this study is voluntary. You have the right to withdraw your consent or discontinue participation at any time without penalty or loss of benefits to which you are otherwise entitled. The alternative is not to participate. The results of this research study may be presented at scientific or professional meetings or published in scientific journals. With your permission, your identity will be made known in written materials resulting from the study.


Age and Competence

This study is only open to persons who are at least 18 years of age and who are competent to consent. If you elect to participate, you affirm that you are at least 18 years of age and are competent to consent.


Contact Information - Questions

If you have any questions, concerns, or complaints about this research, its procedures, risks, and benefits, contact the Protocol Director, Jonathan Mayer.


Contact Information - Independent Contact

If you are not satisfied with how this study is being conducted, or if you have any concerns, complaints, or general questions about the research or your rights as a participant, please contact the Stanford Institutional Review Board (IRB) to speak to someone independent of the research team at (650) 723-2480 or toll free at (866) 680-2906. You can also write to the Stanford IRB, Stanford University, MC 5579, Palo Alto, CA 94304. The study’s protocol is entitled “MetaPhone,” and has been approved by the Stanford IRB between December 20, 2013 and September 27, 2014.