I haven't needed to do this, but I can understand the need and I think you're asking the right questions. Here are my best guesses. I think you can confirm all of them with a little bit of testing.

1. I think the completion/submission, but try it out. Also see what happens if someone returns to a survey and edits a response.
2. Let's see what the answer to question 1.
3. Yes, my best guess is to add a hidden item with an action tag.
4. I'm guessing it's a third option, the server's local time (not UTC, and not the user's local time). But please tell us what you find out.

@thomasnwilson, add anything you'd like.

Okay, I just tested it. Here's what I found:

1. The survey timestamps exported by REDCapR when using the argument export_survey_fields are the survey completion timestamps. If a user goes into the survey after the survey is completed and edits an item, the survey completion time does not get changed. However, if the survey has the following setting enabled ("Allow respondents to return and modify completed responses"), and a respondent returns and modifies a completed response, the survey time see updated (see attached image).
   

2. This question is no longer relevant.

3. A hidden item with an action tag seemed to work well to track the start time of the survey.

4. You might be right. It's either the server time or the local time. I verified that it's not the UTC time. I'm not able to determine whether it's the server time or local time because they are the same for me. I can record both, just in case.

Many thanks!

Cool. Thanks for digging into it. That's good to know for sure for points 1-3.

To disentangle point 4, you can temporarily change your local machine's time and/or timezone

• https://support.microsoft.com/en-us/windows/how-to-set-your-time-and-time-zone-dfaa7122-479f-5b98-2a7b-fa0b6e01b261
• https://linuxize.com/post/how-to-set-or-change-timezone-on-ubuntu-20-04/

One reason I'm guessing that it's the server's time & timezone is that would be a bad thing for a server to trust a client value like that.

Yep, you nailed it. Looks like it's the server time. Thanks for helping me figure that out. That answers all of my questions. Might be helpful to add that to the package documentation--something like: "The timestamps exported using the argument export_survey_fields reflect the timestamp of the survey completion time based on the timezone of the REDCap server."

@isaactpetersen, I like suggestion. See the commit above --would this have made sense to you three days ago (coming fresh into these questions)? If you have better wording, please respond here or send a PR.

If you're happy with it, I'll pull it into the master branch and it will be added to the functions' online documentation.

Looks perfect, thanks for your responsiveness and help with this issue! It is much appreciated.

@wibeasley It seems that REDCap added smart variables for survey start time and survey duration: https://github-wiki-see.page/m/idea-labs/documentation/wiki/Neue-Features-in-REDCap.

For instance, the following smart variables were added in REDCap 12.2.0:
[survey-time-started:instrument]
[survey-date-started:instrument]
[survey-duration:instrument:units]
[survey-duration-completed:instrument:units]

Are these smart variables things that REDCapR can access and export, or do we need to pipe them into survey fields in order to access them via REDCapR?

pipe them into survey fields in order to access them via REDCapR

That's how we've done it in the paste (with other smart variables). Do you have another way in mind? The API pulls whatever is stored in MySQL, and wouldn't have access to the JavaScript/PHP functions.

Edit: And thanks for telling me about these. They'll be useful.

Okay, that makes sense. We'll try piping these values in so we have access to them via export. Thanks!