The Interview Device Related Identifiers - DeviceIndex, DeviceID and SID

SurveyToGo holds several different variables related to the device, that indicate a unique identifier per device/organization/user/interview.

Below are all details and differences between those variables: 

DeviceID: a unique number identifying an installation. It is created on the first login of a user to the App. Re installation will result in a new DeviceID. Upgrades leave it unchanged. This can basically be used to identify a device. You can see the DeviceID when performing Setting->Options and look at the number that appears on the top part of the form. See below, The DeviceID is 65245:

SID: is the unique identifier of a combination User/Device. every user on a specific device has a unique SID. This SID remains the same for that user until/if a new re installation of the SurveyToGo App on the device. Upgrades do not change it.

You can see the sid of the user currently logged on in the app at the top of the screen:

DeviceIndex: a Running index created each time an interview is started. This is regardless the survey or surveyor. Each new interview will get a new DeviceIndex associated with it

Each interview thus has a unique identifier that corresponds to a subject ID which is the combination of the SID and the DeviceIndex in that way:

D<SID>-<DeviceIndex> and can be accessed in the script as the DisplayDeviceIndex 

This is viewed in the OperationsConsole as Global Index.

That is often used as an interview/respondent id when required as explained here: Generating Unique Respondent Id

On the OperationsConsole you also see a column named Index. It is very similar to the GlobalDeviceIndex with a difference that the running Index is for interviews done on that specific survey rather than on any survey on the device (that is represented by the DeviceIndex) and can be accessed in the script using the SurveyIndex property.

So for example let’s say that John works on a specific device. On the first login of John to the App on that device he receives an SID let’s say 123456.

John works on 2 Surveys, A and B with that scenario:

• John starts an interview on A and completes it. The Index it will get is 123456-1
• John starts an interview on A and cancels it (so the interview is deleted, and index 2 for survey A was ‘consumed’)
• John starts an interview on A and completes it. The Index it will get is 123456-3
• John starts an interview on B and completes it. The Index it will get is 123456-1
• John starts an interview on A and completes it. The Index it will get is 123456-2

And so on.

That's it