How do these stand up?

Don't know. Insufficient data.

How tall is each person?

 

Well usually it doesn't really matter how tall, its more related to their legs and their usual slouching/sitting manner.

 

Back to back?

 

True True. Many variables could come into play. What if it's a girl and she's wearing pumps?

 

What if it's a guy wearing pumps? Also, I imagine that if you graphed it, you'd see diminishing returns at certain ranges.

 

I prefer front to front. Personal space is overrated.

 

It would depend on what classes they were taking the first two years vs last two years (joke course load vs rigorous) but my initial thought is that someone who messed up, matured, and then received straight A's in upper level science classes would be preferred over an individual who plateaued.