Which of the following is NOT true of river samples?
a. A river sample is created via the use of banners, pop-ups, or other online devices that invite website visitors to take part in the survey.
b. The "river" is the steady stream of website visitors.
c. The sample frame of a river sample is the stream of visitors visiting the site issuing the invitation.
d. River samples are considered random samples of these sample frames as long as the invitations are not unusual in duration, appearance, or relevance.
e. All of the above are true of river samples.
Answer: e. All of the above are true of river samples.