Should I be worried if not many visitors complete the survey?
Typically, we see response rates of between 15-25% for email surveys and 20-30% for web surveys. And we see around 10% of respondants provide additional (verbatim) comments.
EMAIL: If your response rates to your email surveys are a lot lower than this, it's worth looking at your subject line, the number of other emails you are sending this group of recipients.
WEB: Web surveys placed mid-way through a series of steps (eg mid-way through an e-commerce checkout process) will likely have low response rates as visitors are concentrating on the process. Similarly, surveys on the main homepage will have lower response rates than a survey behind a paywall as plenty of visitors to your homepage will simply 'bounce' (ie move on to another site) without engaging, since they are in browse mode.