October, 1997:
Lead research organization: Ohio State University
Interview dates: September 17 – October 5, 1997
Interview language: English
Mode: Interviews were conducted via landline telephones
Sample: A random digit dial national probability sample of 688 U.S. adults aged 18 and older
Interviews conducted by: Ohio State University Survey Research Unit
AAPOR Response Rate 3: 30%
February, 1998:
Lead research organization: Ohio State University
Interview dates: December 20 – February 13, 1998
Interview language: English
Mode: Interviews were conducted via landline telephones
Sample: A random digit dial national probability sample of 725 U.S. adults aged 18 and older
Interviews conducted by: Ohio State University Survey Research Unit
AAPOR Response Rate 3: 38%
March, 2006:
Lead research organizations: Stanford University, ABC News, Time Magazine Survey
Interview dates: March 9 – March 14, 2006
Interview language: English and Spanish
Mode: Interviews were conducted via landline telephones
Sample: A random digit dial national probability sample of 1,002 U.S. adults aged 18 and older
Interviews conducted by: TNS of Horsham, PA
AAPOR Response Rate 3: 38%
April, 2007
Lead research organizations: Stanford University, ABC News, Washington Post
Interview dates: April 5 – April 10, 2007
Interview language: English and Spanish
Mode: Interviews were conducted via landline telephones
Sample: A random digit dial national probability sample of 1,002 U.S. adults aged 18 and older
Interviews conducted by: TNS of Horsham, PA
AAPOR Response Rate 3: 29%.
April, 2007
Lead research organizations: Stanford University, New Scientist
Interview dates: April 12 – April 18, 2007
Interview language:
Mode: Online research panel – KnowledgePanel
Sample: A random digit dial national probability sample of 1,491 U.S. adults aged 18 and older
Interviews conducted by: Knowledge Networks
AAPOR Response Rate 3: 26%.
June, 2007
Lead research organizations: Stanford University, Associated Press
Interview dates: June 12-14, 2007
Interview language: English and Spanish
Mode: Interviews were conducted via landline telephones
Sample: A random digit dial national probability sample of 1,001 U.S. adults aged 18 and older
Interviews conducted by: Ipsos-Public Affairs
AAPOR Response Rate 3:
September, 2007
Lead research organizations:Stanford University, Associated Press
Interview dates: September 21-23, 2007
Interview language: English and Spanish
Mode: Interviews were conducted via landline telephones
Sample: A random digit dial national probability sample of 1,001 U.S. adults aged 18 and older
Interviews conducted by: Ipsos-Public Affairs
AAPOR Response Rate 3: 3%
July, 2008
Lead research organizations: Stanford University, ABC News, Planet Green Survey.
Interview dates: July 23 – 28, 2008
Interview language: English and Spanish
Mode: Interviews were conducted via landline telephones
Sample: A random digit dial national probability sample of 1,000 U.S. adults aged 18 and older
Interviews conducted by: TNS of Horsham, PA
AAPOR Response Rate 3: 29%
November, 2009
Lead research organization: Stanford University, Associated Press
Interview dates: November 17 – 29, 2009
Interview language: English and Spanish
Mode: Interviews were conducted via landline telephones (705) and on cellular telephones (300)
Sample: A random digit dial national probability sample of 1,005 U.S. adults aged 18 and older
Interviews conducted by: GfK Roper Public Affairs & Media
AAPOR Response Rate 3: 12%
June, 2010
Lead research organizations: Stanford University/ Associated Press
Interview dates: June 1 – 7, 2010
Interview language: English and Spanish
Mode:Interviews were conducted via landline telephones (699) and on cellular telephones (301)
Sample: A random digit dial national probability sample of 1,000 U.S. adults aged 18 and older
Interviews conducted by: GfK Custom Research North America.
AAPOR Response Rate 3: 9%
November, 2010
Lead research organization: Stanford University
Interview dates: November 1 – 14, 2010
Interview language: English and Spanish
Mode: Interviews were conducted via landline telephones (671) and on cellular telephones (330)
Sample: A random digit dial national probability sample of 1,001 U.S. adults aged 18 and older
Interviews conducted by: Abt SRBI
AAPOR Response Rate 3: 17%
September, 2011
Lead research organization: Stanford University, Reuters
Interview dates: September 8 – 12, 2011
Interview language: English and Spanish
Mode: Interviews were conducted via landline telephones (890) and on cellular telephones (244)
Sample: A random digit dial national probability sample of 1,134 U.S. adults aged 18 and older
Interviews conducted by: Ipsos Public Affairs of Washington, DC
AAPOR Response Rate 3: 8%
March, 2012
Lead research organizations: Stanford University, Reuters
Interview dates: March 8-11, 2012.
Interview language: English and Spanish
Mode: Interviews were conducted via landline telephones (853) and on cellular telephones (231)
Sample: A random digit dial national probability sample of 1,084 U.S. adults aged 18 and older
Interviews conducted by: Ipsos Public Affairs of Washington, DC
AAPOR Response Rate 3: 7%
June, 2012
Lead research organizations: Stanford University, USA Today
Interview dates: June 13 – 21, 2012
Interview language: English
Mode: Interviews were conducted via landline telephones (603) and on cellular telephones (201)
Sample: A random digit dial national probability sample of 804 U.S. adults aged 18 and older
Interviews conducted by: Abt SRBI
AAPOR Response Rate 3: 15%
November, 2012
Lead research organizations: Associated Press, Stanford University
Interview dates: November 29 – December 3, 2012
Interview language: English and Spanish
Mode: Interviews were conducted via landline telephones (600) and on cellular telephones (402)
Sample: A random digit dial national probability sample of 1,002 U.S. adults aged 18 and older
Interviews conducted by: GfK Roper Public Affairs & Corporate Communications
AAPOR Response Rate 3: 15%
March, 2013
Lead research organizations: Stanford University
Interview dates: March 3 – 18, 2013
Interview language: English and Spanish
Mode: Interviews were conducted via Internet
Sample: National probability sample of 1,174 U.S. adults aged 18 and older
Interviews conducted by: GfK Custom Research
AAPOR Cumulative Response Rate 2: 2%.
December, 2013
Lead research organizations: Stanford University, Resources for the Future, USA Today
Interview dates: November 20- Dec. 5, 2013
Interview language: English
Mode: Interviews were conducted via landline telephones (521) and on cellular telephones (280)
Sample: A random digit dial national probability sample of 801 U.S. adults aged 18 and older
Interviews conducted by: Abt SRBI
AAPOR Response Rate 3: 13%
June, 2014
Lead research organization: Stanford University, Resources for the Future
Interview dates: June 4 – June 8, 2014
Interview language: English and Spanish
Mode: Interviews were conducted via landline telephones (512) and on cellular telephones (511)
Sample: A random digit dial national probability sample of 1,023 U.S. adults aged 18 and older
Interviews conducted by: SSRS
AAPOR Response Rate 3: 8%
January, 2015
Lead research organization: Stanford University, Resources for the Future, The New York Times
Interview dates: January 7 – 22, 2015
Interview language: English and Spanish
Mode: Interviews were conducted via landline telephones (483) and on cellular telephones (523)
Sample: A random digit dial national probability sample of 1,006 U.S. adults aged 18 and older
Interviews conducted by: SSRS
AAPOR Response Rate 3: 12%
May, 2018
Lead research organization: Stanford University, ABC News, Resources for the Future
Interview dates: May 7 – June 11, 2018
Interview language: English and Spanish
Mode: Interviews were conducted via landline telephones (323) and on cellular telephones (677)
Sample: A random digit dial national probability sample of 1,000 U.S. adults aged 18 and older
Interviews conducted by: ReconMR
AAPOR Response Rate 3: 17%