Upper sample size limit for synching with dropbox

Discussions about syncing data via Bluetooth, Dropbox, FTP, and using CSWeb
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aem1984
Posts: 4
Joined: May 1st, 2019, 5:52 am

Upper sample size limit for synching with dropbox

Post by aem1984 »

Hello,

New to CSPro. I have found setting up a capi data entry program for tablets which syncs with dropbox quite straightforward, however, I see that it is recommended that the Dropbox sync is only recommended for small or medium-sized surveys.

Unfortunately, we do not have anyone on our team with the requisite knowledge to set up CS Web, so I was wondering if anyone knew whether there is, in fact, an upper limit of survey size after which synching via dropbox will not work or is this recommendation made simply because synching large surveys to dropbox would require purchasing more space on dropbox? Our survey will be carried out with 2,525 respondents.
josh
Posts: 2399
Joined: May 5th, 2014, 12:49 pm
Location: Washington DC

Re: Upper sample size limit for synching with dropbox

Post by josh »

The issue is not space on Dropbox rather that since Dropbox is not a database but just a collection of files, every time you sync to upload new cases you add a new file to the Dropbox. As the number of files in the Dropbox gets bigger, syncing gets slower since you have to look through the list of all the files in the Dropbox. So if you have 100 interviewers in the field for 10 days and they each sync once a day you will end up 1,000 files in the Dropbox which is not enough to have a big impact on performance. However if you have a lot more interviewers or your survey period is longer or the interviewers sync more frequently you can potentially end up with millions of files in the Dropbox at which point syncing will be so slow that it will not be usable. We haven't pushed the limits to see at what point it starts to fail and it is hard to give accurate numbers since it depends on a combination of sync frequency, number of interviewers and time the survey is in the field. However, I would guess that with around 2,500 respondents you should be fine.
aem1984
Posts: 4
Joined: May 1st, 2019, 5:52 am

Re: Upper sample size limit for synching with dropbox

Post by aem1984 »

This is extremely helpful! Thank you so much for the detailed reply.
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