These are the basic stats:
Heart - how devoted to the Liberal cause you are. Heart may become lowered by killing an interrogation subject, or from it commiting suicide.
Intelligence - how smart you are
Wisdom - how much you have been corrupted by Conservatives. Wisdom can be increased if you are talking or dating a Conservative and they succeed in influencing you with their talking points.
Health - how much damage you can take before you die
Agility - caps damage for all types of weapons except Clubs and Hand-to-hand combat
Strength - caps damage for Clubs and Hand-to-hand combat
Charisma - how much social skills you have
The questions you answer at the beginning determine the stats for your founder. For everyone else who joins the Liberal Crime Squad, you can find out their initial stats when you are recruiting/seducing/interrogating them. To increase your stats, do activities which increase Juice, to increase your Liberal Rank, which gives an overall bonus (or penalty if negative) to all of your stats. Your stats help to determine the maximum level of various skills, and they also directly affect your abilities to do all sorts of things in the game in the same way skills do. It is best for Heart to be higher than Wisdom, or else the character in question may switch sides to join the Conservative cause if they are put under pressure by Conservatives.
Age affects all stats.
Anyone not in the prime of their life has reduced strength. Old people have reduced agility, health, and heart, but gain charisma, intelligence, and wisdom. Young people (less than 16) have increased heart, but lower intelligence. Children more charismatic, teenagers are less charismatic. [Age effects good as of LCS 4.01.04, although probably still accurate]