Identifying respondents

We use several methods for identifying and remembering respondents and combining each respondent's answers from multiple poll unit visits into one profile.


Our most common identification mechanism is a cookie placed by the poll unit. After the respondent consents, that person is assigned a long random sequence of characters as his or her unique identifier, which is stored in a cookie. The cookie is associated with the domain. This cookie is considered first-party when accessing resources on and third-party when accessing a media partner's domain.

An increasing number of modern browsers disable third-party cookies by default or prohibit them entirely, and privacy-conscious users can install software that disables tracking with third-party cookies. For this reason, we provide another identification mechanism.

HTML5 Local Storage

We use HTML5 local storage to store a backup identifier for the respondent in case the cookie identifier is unavailable. The local storage identifier differs for each website, even for the same person. In other words, the same person will be treated as a different respondent on two different websites. However, for visitors who visit the media partner's website frequently, the local storage identifier is an effective fallback option that bypasses cookie restrictions.