<P> The total number of hours shown in a given week during the performance phase of the competition has varied from two to four hours . In season one there was no results show and the dancers' eliminations were pre-recorded the week they occurred and then broadcast at the beginning of the next week's episode . Seasons 9 - 14 have also utilized one show per week, but with votes from the previous week being revealed later in the show . Voting has varied by season (and often within seasons) with regard to whether the voter selected individuals or couples . There has also been variability in how long couples are kept together and how the at - home - viewer votes are balanced against judge decisions, though ultimately at some point in every season, the judges give up their power to save dancers at this point, and eliminations are determined exclusively by viewer votes, with judges serving in only an advisory capacity . Each season undergoes one final format shake - up in its last week, which typically takes place when the show reaches a Top 4 . In the final performance show, the remaining dancers typically each dance duets with all of their remaining fellow finalists as well as perform solos and participate in group numbers . The following night's season finale episode is often the most elaborately produced show of a season and features the last performances of the competitors, encore performances of many of the season's most acclaimed routines, guest dancers (including returning past season competitors and cast - members from other international versions of the franchise), musical performances and multiple video packets chronicling the course of the season's events, all culminating in the announcement of the winner of the competition, as decided by the previous night's vote . Some seasons have featured a singular winner, while others have allowed for a male and female winner . Following the closure of the season, the Top Ten dancers often go on tour for several months, performing hit routines from the season amongst other performances . </P> <P> The judging panel has also varied considerably in size and composition over the run of the series . Typically a season has 2--3 permanent judges with an additional 1--2 guest judges for most episodes, with the panel ballooning up to six to nine members for Vegas Week and the finale . Executive producer Nigel Lythgoe is the only permanent judge on the panel for all of the seasons . Other permanent judges have included ballroom specialist Mary Murphy, film director and choreographer Adam Shankman and contemporary choreographer Mia Michaels . Guest judge positions are typically filled by choreographers who work regularly on the show--though choreographers will never develop routines for an episode on which they judge--who in rare cases may also be former contestants themselves, and by iconic names from the entertainment industry . Guest judges for the show have included: Debbie Allen, Christina Applegate, Robin Antin, Toni Basil, Cicely Bradley, Kristin Chenoweth, Alex Da Silva, Ellen DeGeneres, Tyce Diorio, Joey Dowling, Napoleon and Tabitha D'umo, Carmen Electra, Brian Friedman, Jean - Marc Généreux, Jason Gilkison, Neil Patrick Harris, Hi - Hat, Katie Holmes, Dan Karaty, Lady Gaga, Carly Rae Jepsen, Lil' C, Rob Marshall, Mandy Moore, Megan Mullally, Kenny Ortega, Toni Redpath, Debbie Reynolds, Wade Robson, Doriana Sanchez, Shane Sparks, Sonya Tayeh, Olisa Thompson, Stacey Tookey, Jesse Tyler Ferguson, and Travis Wall . In earlier seasons, the judges decided on eliminations until around week five of the competitive phase of the show, but in seasons seven through nine the judges decided the eliminations until week seven . Beginning with the twelfth season, Paula Abdul and Jason Derulo joined Lythgoe as permanent judges . For the thirteenth season, 13 - year - old dancer Maddie Ziegler joined the panel as a fourth judge . Season Fourteen has seen the departure of Abdul, Derulo, and Ziegler from their season - long positions of the judges panel, but introduction of Vanessa Hudgens and the return of Mary Murphy to her seat . </P> <Table> <Tr> <Th> Season </Th> <Th> Dates </Th> <Th> Host </Th> <Th> Permanent judges </Th> <Th> Separate results show? </Th> <Th> Dancer showcase episode? † </Th> <Th> Number of finalists in first live show </Th> <Th> Number of contestants eliminated per week </Th> <Th> Number of contestants remaining in finale </Th> <Th> No. of winners </Th> <Th> All - Stars included in format? </Th> <Th> Point at which judge eliminations end </Th> <Th> Voting for individual dancers starting with </Th> </Tr> <Tr> <Td> </Td> <Td> Summer 2005 (July--October) </Td> <Td> Lauren Sánchez </Td> <Td> Nigel Lythgoe </Td> <Td> No </Td> <Td> No </Td> <Td> 16 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> No </Td> <Td> Top 8 </Td> <Td> Top 8 </Td> </Tr> <Tr> <Td> </Td> <Td> Summer 2006 (May--August) </Td> <Td> Cat Deeley </Td> <Td> Yes </Td> <Td> No </Td> <Td> 20 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> No </Td> <Td> Top 10 </Td> <Td> Top 10 </Td> </Tr> <Tr> <Td> </Td> <Td> Summer 2007 (May--August) </Td> <Td> Nigel Lythgoe Mary Murphy </Td> <Td> Yes </Td> <Td> No </Td> <Td> 20 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> No </Td> <Td> Top 10 </Td> <Td> Top 10 </Td> </Tr> <Tr> <Td> </Td> <Td> Summer 2008 (May--August) </Td> <Td> Yes </Td> <Td> No </Td> <Td> 20 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> No </Td> <Td> Top 10 </Td> <Td> Top 10 </Td> </Tr> <Tr> <Td> 5 </Td> <Td> Summer 2009 (May--August) </Td> <Td> Yes </Td> <Td> No </Td> <Td> 20 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> No </Td> <Td> Top 10 </Td> <Td> Top 10 </Td> </Tr> <Tr> <Td> 6 </Td> <Td> Fall 2009 (September--December) </Td> <Td> Nigel Lythgoe Mary Murphy Adam Shankman </Td> <Td> Yes </Td> <Td> Yes </Td> <Td> 20 </Td> <Td> </Td> <Td> 6 </Td> <Td> </Td> <Td> No </Td> <Td> Top 10 </Td> <Td> Top 10 </Td> </Tr> <Tr> <Td> 7 </Td> <Td> Summer 2010 (May--August) </Td> <Td> Nigel Lythgoe Adam Shankman Mia Michaels </Td> <Td> Yes </Td> <Td> Yes </Td> <Td> 11 </Td> <Td> 1 * </Td> <Td> </Td> <Td> </Td> <Td> Yes </Td> <Td> Top 4 </Td> <Td> Top 11 </Td> </Tr> <Tr> <Td> 8 </Td> <Td> Summer 2011 (May--August) </Td> <Td> Nigel Lythgoe Mary Murphy </Td> <Td> Yes </Td> <Td> Yes ‡ </Td> <Td> 20 </Td> <Td> 2 * </Td> <Td> </Td> <Td> </Td> <Td> Yes </Td> <Td> Top 6 </Td> <Td> Top 10 </Td> </Tr> <Tr> <Td> 9 </Td> <Td> Summer 2012 (May--September) </Td> <Td> No </Td> <Td> Yes ‡ </Td> <Td> 20 </Td> <Td> 2 * </Td> <Td> </Td> <Td> </Td> <Td> Yes </Td> <Td> Top 6 </Td> <Td> Top 20 </Td> </Tr> <Tr> <Td> 10 </Td> <Td> Summer 2013 (May--September) </Td> <Td> No </Td> <Td> Yes ‡ </Td> <Td> 20 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> Yes </Td> <Td> Top 6 </Td> <Td> Top 20 </Td> </Tr> <Tr> <Td> 11 </Td> <Td> Summer 2014 (May--September) </Td> <Td> No </Td> <Td> Yes </Td> <Td> 20 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> Yes </Td> <Td> Top 10 </Td> <Td> Top 20 </Td> </Tr> <Tr> <Td> 12 </Td> <Td> Summer 2015 (June--September) </Td> <Td> Nigel Lythgoe Paula Abdul Jason Derulo </Td> <Td> No </Td> <Td> Yes </Td> <Td> 20 </Td> <Td> 2 ⁂ </Td> <Td> </Td> <Td> </Td> <Td> Yes </Td> <Td> Top 14 </Td> <Td> Top 20 </Td> </Tr> <Tr> <Td> 13 ° </Td> <Td> Summer 2016 (May--September) </Td> <Td> Nigel Lythgoe Paula Abdul Jason Derulo Maddie Ziegler </Td> <Td> No </Td> <Td> Yes </Td> <Td> 10 </Td> <Td> 1 * * </Td> <Td> </Td> <Td> </Td> <Td> Yes </Td> <Td> Top 8 </Td> <Td> Top 10 </Td> </Tr> <Tr> <Td> 14 </Td> <Td> Summer 2017 (June--September) </Td> <Td> Nigel Lythgoe Mary Murphy Vanessa Hudgens </Td> <Td> No </Td> <Td> No </Td> <Td> 10 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> Yes </Td> <Td> Top 6 </Td> <Td> Top 10 </Td> </Tr> </Table> <Tr> <Th> Season </Th> <Th> Dates </Th> <Th> Host </Th> <Th> Permanent judges </Th> <Th> Separate results show? </Th> <Th> Dancer showcase episode? † </Th> <Th> Number of finalists in first live show </Th> <Th> Number of contestants eliminated per week </Th> <Th> Number of contestants remaining in finale </Th> <Th> No. of winners </Th> <Th> All - Stars included in format? </Th> <Th> Point at which judge eliminations end </Th> <Th> Voting for individual dancers starting with </Th> </Tr>

Who are the judges of so you think you dance