Comparing floating point numbers and precision problems

Our development team often receives reports on suspected bugs in Survey Solutions on the grounds of a situation similar to the one described below. These reports stem from misunderstanding of some fundamental concepts of how computations are done by a computer, and not due to an actual defect of the software. Problem description Suppose you have a questionnaire containing two numeric questions X and Y, and a third question Z with an enabling condition (X*Y) == 21.

February 6, 2017

What to do in case a tablet gets broken, damaged, or destroyed.

The tablets used for data collection may get damaged or broken during the field work. If this happens: interviewer should immediately report this to his/her supervisor; supervisor should inspect the tablet and confirm the damage (often interviewers report tablets as broken when the tablets completely discharge and require long-press for power button to power up); supervisor should record the loss of a tablet and issue a replacement (possibly taking notes on the specifics of the devices lost and issued: model, serial number, date, interviewer name and login, circumstances of the loss, etc).

January 23, 2017

Should and could I modify my questionnaire when the survey is in the field?

You could modify your questionnaire when the survey is already in the field. Survey Solutions treats any modifications of a questionnaire as a new survey. Even if the changes are minor, the modified questionnaire will be shown as a new survey both on tablets and in the HQ/Supervisor application. In general, we strongly advise against making changes in the questionnaire after the survey goes to the field. We do advise to plan extensive pre-testing and piloting survey prior to the field.

October 21, 2016

Should I buy cheap tablets?

Our users often ask us about the minimal specification for the tablets to be used with Survey Solutions. While we understand the desire to cut costs of conducting surveys, we recommend purchasing the most powerful tablets you can afford. With a very few exceptions, the total survey budget is much larger compared to the budget you spend even on the most powerful tablets. Modern tablets provide much better interviewer experience: they are more responsive and have longer battery life.

September 20, 2016

Why does the time recorded through date/time question is different from the time reported in GPS question?

An Android tablet has its internal clock. That clock is set based on specifications of the tablet manufacturer and on the user settings. For example, the tablet clock can be synchronized to the network time, or can be set by tablet users manually. The time reported in GPS question comes from the GPS signal provider. We recommend acquiring the GPS signal through satellites disabling the wifi coordinate services. However, geographic coordinates might be acquired through wifi.

September 9, 2016

My Survey Solutions server is not the latest version. Can I still use it with new surveys?

It is recommended that you upgrade your server to the latest version, but as long as you use only features that were available on your version of the server the new survey should work on the older server. Please note that you will not be able to import to the server questionnaires with features introduced in versions that are later than the version of your server.

September 7, 2016

Does Survey Solutions require constant internet connection to collect data?

No, Survey Solutions does not require constant internet connection. The data collection on tablet can be conducted offline. The internet connectivity, either 3G/4G or WiFi, is required to synchronize tablet with the server to send completed assignments and to receive new assignments. In some cases, i.e., remote Pacific islands, interviewers go without connection for several weeks. While it is possible not to synchronize for an extended period of time, we recommend to synchronise tablets as often as possible, preferably after each interview, if the connectivity allows.

September 7, 2016

How can I request localization for the Interviewer and Tester in a new language?

Please contact our developer team and request the localization. We will review your request and, if approved, we will send you Excel files with strings to translate. Once we receive the files with translation from you, we will try integrating the new translation into the next release. However, you should realise that the initial translation is just part of the localisation work. The most time consuming task is to support the localization for the new versions.

September 7, 2016

Is Internet access required during interviews?

No. Internet access is only required to synchronize data and case assignments, and is not needed during interviews. In some cases the interviewers might go without connection for weeks (for example, remote islands in the Pacific). They synchronize with the server when they reach the location with 3G of WiFi internet coverage.

September 7, 2016

Is there an offline version of the questionnaire designer?

No. The Questionnaire Designer can only be used online. Survey Solutions evolves very rapidly and we are introducing new features with each monthly release. An online designer allows us to maintain the version compatibility. Another argument in favor of online designer is that in order to use any CAPI software a tablet has to communicate to a server. So, the internet connection is necessary for data collection and thus should also be available for Questionnaire Designer.

September 7, 2016