A survey is considered Viewed if a respondent clicks on the link and views the first page of a survey. A survey is considered Started if a respondent clicks Continue on the first page of the survey.
The Participation Rate is the percentage of people who have Started or submitted at least one page of the survey after viewing it.
If a survey is in Started status, then the respondent has not completed the survey. After all responses have been submitted, the survey moves to Completed.