What is this study?

This is a study conducted by the University of Maryland and Fraunhofer USA to better understand how people use smartphones in the course of their daily lives. Prof. Maimon describes this research project in a short video available here.

Am I eligible to participate?

In order to participate you must:

  • Be 18 years or older
  • Own an Android smartphone, e.g., a Samsung, Nexus, LG, or HTC phone with a touch screen.

How do I sign up?

To sign-up for the study, complete the short survey at https://www.surveymonkey.com/r/pocket_security. If you already completed our survey in person at one of our sign up stations, skip this step!

I finished the survey. Now what?

The University of Maryland team will select approximately 150 study participants from those that completed the sign-up survey.

If you are selected to participate in the study, the research team will contact you within a few weeks. At that time, you will receive more detailed instructions. The study will involve another survey, filling out paperwork that explains your rights and responsibilities to receive compensation, and installing a smartphone app that collects data on how you use your smartphone. Only people who participate in this part of the study are eligible for compensation.

We cannot guarantee that everyone who signs up will be chosen to participate in the study.

What are the benefits to me?

If you participate in the main part of the study where we collect data from your smartphone, you are eligible to receive up to $80 per month for three months toward your smartphone bill. The exact terms and conditions of this payment will be provided if you are selected for the study. You will be required to complete an IRS W-9 form and other legal documents.

There are no benefits to participating in the sign-up survey.

Right to Withdraw

Participation in this research is completely voluntary. You may choose not to take part at all. If you decide to participate in this research, you may stop participating at any time.

If you decide to stop taking part in the study, have questions, concerns, or complaints, please contact:
David Maimon
2220F LeFrak Hall, 7251 Preinkert Dr. College Park, MD 20742
Email: dmaimon@umd.edu, Tel: 301-405-4699

Madeline Diep
5825 University Research Ct., Suite 1300, College Park, MD 20740
Email: mdiep@cese.fraunhofer.org, Tel: 240-487-2905

What is the MADCAP app?

The MADCAP app is an Android application that collects information about how smartphones are used “in the wild”. We use the data in collected by this app to better understand where and when people do certain things on their phones, such as browsing the web, texting, installing new apps, or connecting to wifi networks.

What data does MADCAP collect?

MADCAP collects events that occur on your device. For example, receiving phones calls, sending texts, switching to airplane mode, or plugging in your device to a power source. We also periodically collect the GPS coordinates of your phone, whether the phone is moving or not, and which applications are running on the phone.

We do not collect the content of your calls, texts, web browser, contact lists, photos or any other private information. We do not know who you called or texted, or who called or texted you.

Here is a complete list of data that we collect:

  • When you make and receive calls, but not who you call or what you say
  • When you make or receives text or MMS messages, but not who you were texting with or the contents of those texts
  • Which applications are running on your phone, but not anything about what you are typing or viewing in those applications. For example, we collect that your phone’s Web Browser is running, but we do not collect which pages you visit or what you type.
  • The name of the WiFi network you are connected to, if any.
  • When a Bluetooth device, such as an earpiece or speaker, are connected to your phone.
  • Your GPS location as reported by your phone
  • If your phone’s speaker is in use, such as when you are playing music or listening to a phone call. We do not record anything about what is playing – only that there is noise coming through the speaker.
  • Changes in your phone’s position, such as when you pick it up from a table.
  • The amount of charge on your battery and whether your phone is plugged into a power source or not.
  • When your phone is shutting down, in airplane mode, in a screensaver, or when a headset is plugged in or removed.

Privacy and Confidentiality

We will keep personal information confidential. Any information that is obtained in connection with this study and that can be identified with you will remain confidential and will be disclosed only with your permission or as required by law.

Your name and contact information that you provided at the beginning of the study is kept separately from your MADCAP data. The MADCAP data will be linked to your name and contact information via a code number, and this mapping will only be available to the research team. This mapping of code numbers to contact information will be destroyed upon completion of the research program.

Information that can identify you individually will not be released to anyone outside the study. Any information we use for publication and analysis will not identify you. Your GPS location information is considered especially sensitive. We will never release this information outside the research team without removing or randomly changing this data (for example, by changing your coordinates so they are in the middle of the ocean) so that no one can see your real locations.

For more information on privacy of your data, please read our Privacy Policy.


  1. Can you see the content of my apps, texts, browser, phone calls, contacts, files, or photos?

    No, we cannot see content. We are interested in events. For example:

    • We collect when you send or receive a text message. We do not collect who you sent the message to or the contents of the message.
    • We collect which apps are running, but not what you are doing in the app. For example, we observe that you use a web browser, but we do not observe which websites you visit.
    • We do not collect any information regarding your contacts list, files on your device, or photos.
  2. Can I suspend data collection, such as when I am at work?

    Yes. There is a switch button in the app which you can move between On and Off. When Off, no data will be collected.

  3. I changed my mind and no longer wish to participate. What do I do?

    Please refer to the opt out instructions.

  4. Does the app collect any personally-identifiable information (PII)?

    We collect an ID number from Google that is unique to your Google account so that we can distinguish data between individuals. However, this information will never be shared or included in reports. We cannot and do not use this Google account ID number in any other way. No other PII is collected by the app.

  5. What about my location data, such as GPS coordinates?

    We do periodically collect this data from your phone.

  6. Will you share my data outside your research team?

    Your name, email address, or any other personally-identifiable information will never be shared or associated with your data. We will release anonymized data so that other researchers may benefit from this study. GPS data will also be removed from any shared data, or we will modify the GPS data such that it is moved away from your actual location.

  7. I am still a little uneasy about my privacy…

    Understandable. We have MADCAP installed on our own phones, and our family and friends use it as well. We have a vested interest in preserving the privacy and trust of everyone in this study.

  8. Will the app eat up my battery?

    It is hard to determine how much battery the app will use because it depends on your battery’s capacity and condition. Old batteries do not hold as much charge, nor do hot batteries, and batteries discharge more quickly when they are nearly empty. Bearing this in mind, here are some estimates based on a healthy, fully-charged battery:

    • Go to Settings -> More -> Battery to see some statistics on your battery usage.
    • When MADCAP is collecting data but not uploading via WiFi, it drains approximately 1.5-2x as much battery as the Android System. This amounted to about 3% of my battery on a Samsung Galaxy S4 over 8 hours.
    • When MADCAP is collecting data AND uploading via WiFi, it drains 4-5x as much battery as the Android System. This amounted to about 6% of my battery on a Samsung Galaxy S4 over 8 hours.
  9. Will the app use up my data plan?

    No. The app will only upload data to us when it is connected to a WiFi network.

  10. How can I see the data that you have collected so far?

    Send an email request to mdiep@cese.fraunhofer.org including your GMail address and we will provide you with a copy of your data.

  11. Do you have IRB approval?

    We have submitted our IRB package to the University of Maryland IRB and are iterating with them. We will post the approval letter here once we obtain it.

  12. How much storage space does the app use?

    It depends on how many data points you have saved on your phone. The app itself is around 10 megabytes. The average size of a data point is 1.6KB. The app collects approximately 3,300 data points per hour. Thus:

    • If you are connected to WiFi and the app is uploading its data on schedule, the app will use around 11MB of space.
    • If you go one hour without uploading, the app will use approximately 15MB of space.
    • If you go one day without uploading, the app will use approximately 137MB of space.
    • The app will start to “clean house” if you have too much data saved in order to preserve space. Currently, it will clean up at 100,000 entries, which is approximately 30 hours of data. So, in the worst case, the app will take approximately 170MB.

    In the future, we will be working to shrink the amount of space the app takes.