The Favorability Index - or 'FavIndx' - applies a numerical value to a presidential candidate based on total number of states won and the overall victory spread of a given state. The results provide a candidate's 'favorability' rating, showing just how popular (or unpopular) he/she was at the moment of victory. Generally, the larger the state victories the greater the score. However, in some races - particularly close ones - the losing candidate may score better than the winning candidate.
Two of the best performers are Richard Nixon (1972) and Ronald Reagon (1984) while two of the worst performers are their counterparts, George McGovern (1972) and Walter Mondale (1984). The highest possible FavIndx rating achieved is by Republican Richard Nixon in the 1972 campaign with a score of 1355.5. When averaged out, Ronald Reagan and George W. Bush are the top-performing Republican candidates while Bill Clinton and Barack Obama are the two top Democratic candidates. Both Reagan, Bush, and Clinton (Bill) all scored better in their second campaigns whereas Obama scored better in his first outing.
For the 2020 election, Republican candidate Donald Trump (248.1) slipped in the FavIndx from his 2016 showing (347.3) against Democratic challenger Hillary Clinton (166.1) - but still managed to edge out Democratic challenger (and eventual winner) Joe Biden (241.6).