the right CAPI
device for Nfield

Even though Nfield CAPI runs on all Android tablets and smartphones, not every device will serve you accordingly. For example, some devices don’t come with a memory card or processor powerful enough to support such sophisticated software. Please refer to our guide below as many factors come into play
The types of surveys and their environment heavily influence the mobile device that should be employed. Factors for selecting the right device for your CAPI projects fall under two categorizes, technical and practical.

The recommended specifications of an Nfield CAPI device
Android version - 7.0 or higher
Processor - Quad core or more
Memory - 4GB RAM or more
Storage - At least 32 GB

Practical factors cover screen size, cameras, GPS, battery life and safety.
The technical and practical factors are intertwined, so you shouldn’t evaluate them separately when selecting a device. As a starting point, we recommend that customers follow the minimum technical requirements to ensure the Nfield CAPI app runs smoothly, and then factor in the practical considerations. In the text further we cover the practical factors.


Test the device before you buy it; your supplier should be amenable to a test period. 

Screen size

Consider the media files, security and the types of survey to select an ideal screen size. For example, the best match for quick polls might be a 3.5”- 5” screen. Devices are usually offered in three sizes:
  • Mini 3.5”-5” screens draw less attention, and are perfect for projects that don’t require many photos or videos.
  • Versatile 7”/8” screens allow the device to be used for many types of survey.
  • Big 10” screens are convenient for surveys that require lots of media files to engage your respondents. The bigger the screen, the higher the screen resolution which renders good quality photos and videos. However, large tablets are always handy to carry and may draw more attention.


Most devices on the market come with two cameras: backward and forward facing. The backward facing camera - which has a higher resolution - is used to take photos during the interview. These photos serve two purposes: firstly as an additional source of information for research analysis; and secondly for silent photo capturing to monitor the interviewers to ensure that they maintain the highest standards.
Generally, the front camera is used for selfies and online calls. Having both cameras in face-to-face interviewing enables you to perform a precise silent-photo or video capture that will give you a complete view of the surroundings of the interviewer.


The camera resolution determines the size of the photos taken. If they are too big, it will slow down the speed of data transfer in Nfield CAPI.


GPS represents an indispensable source for your quality control. The GPS hardware captures a location by contacting satellites to pinpoint the location of your device anywhere in the world. The accuracy of this is dependent on various factors such as: the number of satellites in view, mountains and ionospheric disturbances, signal interference caused by buildings, and the number of channels on the receiver.
Please ensure that your device is equipped with a GPS receiver which is an electronic device that uses signals transmitted by GPS satellites to determine its location (latitude, longitude and elevation).

Battery life

For interviews carried out in remote places, battery life is literally a question of success or failure. If the battery gets discharged, the interviewer is forced to stop his work. Please pay attention to the stated maximum battery life when evaluating device options, and share our recommendations below on how to prolong a battery life in the field with your interviewers.
  • Screen brightness is the number one consumer of battery life, therefore maintain the lowest level that’s comfortable.
  • Turn off your device when not in use.
  • The GPS consumes much energy when contacting satellites so only activate it when you are ready to conduct an interview.
  • Surfing on internet via 4G or WiFi drains a battery significantly. Use the internet primarily for syncing the interviews, and turn the connection off when not in use.
  • Close all apps that are running in the background such as WhatsApp, Facebook, Instagram, the browser and countless others.


    Bear in mind that the stated maximum battery life is valid for the use with a minimum brightness.


    The device’s overall appearance tends to draw attention, therefore you need to consider the safety of your interviewers, the devices and the data. Provide your interviewers with a covering to disguise the device when walking around, and opt for smaller and less appealing devices if your interviewers visit more risky areas.
    Device providers usually offer a free service that enables you to trace a device or wipe it remotely in the event of loss. Familiarise yourself with this option so that you know what to do should anything happen.  Mobile Device Management (MDM) software is widely available to help you configure, manage and secure mobile devices, with additional features available at a cost.

    EXTRA: Updating your device

    There are two types of software updates that you need to be aware of:
    • Nfield CAPI app updates
    • Android operating system updates
        Nfield CAPI app updates (NIPO)
        The Nfield CAPI app is managed by NIPO, and any updates are designed solely to augment the features of the app. Every release automatically updates the backend of Nfield CAPI but requires the manual intervention of the interviewer to take effect on the device.


      Please ensure your interviewers allow automatic updates of the Nfield CAPI app so that they are working with the latest version which supports data security and provides the most-up-to-date features to them.  To allow automatic updates, ask your interviewers to open the Play Store app and set the Nfield CAPI app setting to “Allow automatic updating.”  Our Support Team will always send you detailed information via email about any app updates the day before the new version is released, so please do look out for these.
      Android operating system updates (Google)
      All Android operating system updates are managed by a third party - Google. These updates impact the software that the whole device runs on; they are not primarily calibrated to Nfield CAPI functionality.
      The Android operating system update usually starts by a window which automatically opens on the screen asking for permission to update the operating system.  The interviewer will need to consent to this before any updates can take place. In other words, the update doesn’t happen automatically.

      Whilst we thoroughly test all major updates of the Android operating system to examine whether Nfield CAPI features have not been affected, due to the diversity of mobile devices available and the number of versions of the Android operating being used at any one time, it makes in-depth testing on a large scale impossible.  


      Only update the operating system on a few devices first to ensure everything still works as it should before you push out an extensive update across all of your devices. Inform your interviewers that they shouldn’t update the device without your consent to prevent unwelcome disruptions of the fieldwork. By acquiring the aforementioned Mobil Device Management (MDM) service, you can even manage and schedule software updates for all devices yourself. And most importantly, our Support Team is always on hand to help you.

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