The following sources were used to compile the January 2019 edition of the 100 Great Sci-Fi list. Each source was added to a formula, and weighted on both critical value and recency. This means ranking higher on newer lists is more valuable than ranking higher on older lists.

For 2019, Flickchart user rankings replaced IMDb ratings. I also added a new list from the website Best Science Fiction Books, updated lists that changed in 2018 and downgraded the value of older lists.

Academy Award Best Picture Winners & Nominees (1929-2018)
AFI's 100 Years... 100 Movies  - 10th Anniversary Edition(2007)
AFI Awards (2000 - 2019)
AFI's Top 10 Sci-Fi (2008)
Best Science Fiction Books’ Top 50 Science Fiction Movies of All Time (2018)
BFI's 100 Science Fiction Films (2015)
The Black Film Canon (2016)
Cinema Fanatic's A Year With Women (2015)
Domestic Box Office by Tickets Sold (2019)
Flickchart Highest Ranking Science Fiction Films (2019)
Golden Globe Best Drama & Best Musical/Comedy Winners and Nominees (1944-2018)
Little White Lies' 100 Great Movies by Female Directors (2015)
Palme d'Or Winners (1955 - 2018)
Roger Ebert's Great Movies (2013)
Sight & Sound Critics Poll (2012)
Sight & Sound Directors Poll (2012)
Time Out's The 100 Best Sci-Fi Movies (2017)
Total Sci-Fi's The 100 Greatest Sci-Fi Movies (2009)

If you have any source suggestions for the 2020 version, please email me at adamcallroberts@gmail.com