Home - Grow Offline Sales Certification - Data from store visits is validated through a panel of volunteer Google Opinion Rewards participants. How many volunteer participants are there? Data from store visits is validated through a panel of volunteer Google Opinion Rewards participants. How many volunteer participants are there? 2shares Facebook Twitter Pinterest LinkedIn Skype Facebook MessengerQuestion: Data from store visits is validated through a panel of volunteer Google Opinion Rewards participants. How many volunteer participants are there? 1 million 500,000 100,000 5 million The right answer was: 5 million