SurveyMonkey surveys can optionally be made "anonymous", preventing respondents' email and IP addresses from appearing in the survey results.
As a respondent, how can I verify that a survey has been made anonymous? Do I just have to take the author's word for it?
The instructions for creating "anonymous" surveys suggest that SurveyMonkey is aware of this concern:
Put your survey recipients at ease by informing your survey respondents about whether their responses are being provided anonymously.
This sounds hopeful, but their subsequent recommendation is worrisome:
You can add a privacy disclosure for your survey by inserting it as introductory text on the front page of your survey.
The document titled Are my survey responses anonymous and secure? sounds like it might address this. For each issue, anonymity and security, the document describes pertinent features that can be enabled by the survey creator.
For the issue of security, the document also explains how a respondent can identify whether the pertinent features are in effect. Disappointingly, no such guidance is provided for the issue of anonymity.