This page was used to answer FAQs by the participants in our study

While the data collection is over, the page provides general information and some technical details about the study protocol.

Use of the mobile application

I'm not going out tonight, should I use the application?

Yes!! Absolutely!
More than half of alcohol consumption takes place in a private setting. All evenings, whether you are going out or not, whether you are drinking or not, are important. In order to have a representative overview of young adults' life on Friday and Saturday nights, at any time and place, it is essential that you document what happens when you don't go out as well.

I'm leaving Lausanne/Zurich for a few days, can I use the application?

The study is, above all, about the context of consumption (loudness, luminosity, etc.). The location that you are in, even abroad, doesn't really matter.

In any case, the application is only designed to send data onto the server via the use of the WiFi network that you chose; therefore you won't be charged for any mobile connection costs. However, if you are abroad you will have to deactivate the GPS as it can produce roaming costs.

Pictures of drinks: good and bad examples

We want to know the exact volume of liquid contained in the glass. Please follow these guidelines to take photos of drinks:

  1. Use the image resolution you normally use, but make sure that at least a minimum resolution of 1280 x 720 is used.
  2. Use the PORTRAIT format of the camera (vertical). The drink should appear centered and big in the photo.
  3. Make sure the full glass/cup appears in the photo. Do NOT capture only a part of the glass.
  4. The photo should capture a frontal view of the drink. Do NOT get top views of the drink.
  5. Follow your common sense and use the camera flash if you think it's necessary. Photos that are too dark are not useful.
  6. Focus on your current drink; if there are several glasses next to your current glass, focus on yours.
  7. We are not interested in artistic photos but on photos that clearly show the drink. Do NOT use any special filters, etc.


Videos of the environment: good and bad examples

In order to be able to measure the surrounding loudness and luminosity, you are requested to make short videos (about 10 seconds) showing the atmosphere of the place that you're in when you're going to have a drink. For this reason, we would like to have about a 360° panorama of the location (from left to right or from right to left), which doesn't only focus on dark or bright areas. It is also important that the microphone can capture the sound (e.g. not covered up with a finger). Please follow these guidelines to take videos of venues:

  1. Use the video resolution you normally use, but make sure that at least a minimum resolution of 1280 x 720 is used.
  2. Use the LANDSCAPE format of the camera (horizontal) to take videos.
  3. Generate a full view of the venue by SLOWLY moving the camera from left to right. You have 10 seconds to record the video. Do NOT move too fast or the video will be blurry.
  4. Show the whole scene rather than the table or your friends in front of you. It might be a good idea to stand up or lift your arms when you take the video.
  5. Take a video even if the scene is dark. Follow your common sense and use the camera flash if you think it's necessary. Videos that are too dark are not useful.
  6. Make sure the microphone of the phone is not covered by your fingers. We want to capture the real sound level of the place.
  7. We are not interested in artistic videos but on videos that clearly show the place. Do NOT use any special filters, etc.

The video can also be used to define the environment (like the number of people) and, if you take part in a qualitative interview, as a support to talk about an evening in particular.

We draw your attention to the fact that certain places (e.g. museums) forbid videos. Furthermore, depending on the circumstances, certain people might be indisposed to video making. Therefore, we ask you to (a) respect the location's instructions and (b) not to make a video if you feel that the moment is inappropriate.

In any case, we guarantee that these videos will never be used to recognize the faces of people who might be in them and that they will never be published in any form.

Setting up the mobile application

Accepted smartphones

All devices equipped with an Android operating system (version 4.0.3 or more recent), these being most Samsung, Sony and HTC devices, will be able to set up the mobile application allowing them to take part in the evening study. However, devices equipped with iOS (iPhone), WindowsPhone(Nokia) or Blackberry aren't compatible.

To check your Android operating system version, see for example:

Downloading the application

The application will be available for download on your phone only for registered participants. The application is specific to the study, and it is not available on Google Play Store.

Setting up the application

When you're setting up the application, it is essential that you allow access to the different sensors to ensure the proper functioning of the application.

You will need to install two applications: Please install the SensorService.apk BEFORE installing YouthAtNightApp.apk !

Changing your smartphone during the study

It is only possible to change your phone during the study if you replace it with one that is compatible with the mobile application (see "accepted smartphones" section). However, no procedure to be followed has been planned if this happens. Ideally, you shouldn't lose , break or drown your phone, or change your operator, during the study.

Likewise, it is essential that you take your phone with you on Friday and Saturday nights that are dedicated to the study. Therefore, you cannot share your phone with other people during this time.

Uninstalling the application

To unregister during the study, please send us an email at and then uninstall the application from your phone.

If you can't or don't want to take part in the study during one or the other evening, or if the moment isn't appropriate, you can simply switch off the application or postpone the notification signals.

Application source code

The source code of the application will be made available for the research community in the future. If you want to stay informed send us an email at

Collected data

Which data is collected and for which use?

The baseline questionnaire (to be filled in after registration) will be used for collecting general information about the participants and their going out and alcohol consumption habits on Friday and Saturday nights. This questionnaire contains questions about:

The mobile application will be used to follow the evolution of alcohol consumption during the evening according to the physical and social environment. For every drink consumed, participants are asked to:

Moreover, in order to follow travels throughout the evening and to characterize visited places, the application will regularly record:

When installed, the application will record the device's IMEI number, the type of device and the OS version to ensure the application's optimal functioning.

Finally, while it is being used, the application will regularly check the battery charging state, the phone's parameters (e.g. silent mode, etc.) and the available RAM memory.

This data won't be passed on to the study's server or stored in the application.

The final questionnaire (to be filled in after the study with the mobile application) will be used to collect participants' opinions and experiences, an estimate of alcohol consumed during the study and a reminder of places visited during the study. This questionnaire will also enable you to sign up for a qualitative interview (see Interviews section)

Protection of personal data and anonymity

Your data will be treated in a strictly confidential way. We guarantee that no personal information will be used for other studies or communicated to a third party. Moreover, results will be based upon groups of people and therefore identifying people individually will be impossible.

Information exchanges between your phone and the server will be coded according to the most advanced procedures.

How can I erase my data?

As a participant you have up to 7 days after the end of the study to ask for the suppression of data that you do not want to be kept in the final database. To erase data, please fill out the form on the "Remove Content" page and indicate which data you would like to erase. The administrator of the database will see to this and will confirm the removal to you.

Qualitative interviews

How do the qualitative interviews take place?

The qualitative interviews will allow you to go back on the experiences you had during the evenings of the study and also, on the basis of your experience, to develop the links between nightlife, locations, and alcohol consumption.

Before the beginning of the interview, the participant will be informed about the interview's anonymisation procedures (see below), the use of the data and his right not to answer every question, and to interrupt the interview at all times. The participant will also be informed that the results will be published as a scientific publication. A consent form, going over the elements above, will also be signed for each participant. Each interview will last between 1 hour and 1 hour and a half and will be recorded (audio) and then transcribed again.

Anonymisation of the interviews

Participants' names and all the names of the people mentioned during the interview will be anonymised during transcription.

Transcripts will only be used by the members of the three research teams.

Sentence extracts (quotations) quoted in the publications are assigned to the anonymised names.

When the quotations include descriptions of events or of sensitive experiences, the participant's characteristics and those of the people mentioned, which aren't relevant to the research question, will be changed (e.g. exact age, gender, etc.)

Furthermore, the research associates are asked not to speak of the context or content of the interviews outside the research project.

Interview content

The interview topic is your experience while you go out in town for the evening and your view on certain nightlife locations in Lausanne/Zurich. The following themes will be addressed:

During the interview, we will also ask you to watch and comment a few clips of the videos that you made with your phone for this study

Costs and Remuneration

How much does taking part in the study cost?

The mobile application is free and taking part in the study doesn't cost anything in terms of mobile data transfer costs. When you install the mobile application, data will be transferred to the study server via WiFi points that you are connected to. No data will be transferred via mobile network.

How long do I have to stay in the study to obtain the 100.- CHF remuneration?

Participation in seven weekends during the first part of the study will be paid 100.- CHF, transferred to your bank account at the end of the study.

What remuneration is intended for the qualitative interview?

Participation in a qualitative interview (second, optional, part of the study) is paid 25.- CHF, in addition to the remuneration mentioned above.