The sampling designs that use voluntary response sampling are #1, #2, #4, and #6
Step-by-step explanation:
Participating in an online survey, online voting polls, and requesting for others to complete a survey are all sampling designs that use voluntary response samplings.
A voluntary response sample is defined as a type of sample made up of self-chosen participants. These participants volunteer to take part in different research studies to share their opinions on topics that interest them. A voluntary response sample is made up of persons who volunteer to take research surveys.
