Aggregate linear regression

Question

Sorry I am quite new to R, but I have a dataframe with gamelogs for multiple players. I am trying to get the slope coefficient for each player\'s points over all of their games.

Answer 1

You can also do some magic with the base lm to do it all at once:

coef(lm(game ~ pts*name - pts, data=gamelogs))[3:4]
coef(lm(game ~ pts:name + name, data=gamelogs))[3:4]
#pts:nameplayer1 pts:nameplayer2 
#    -0.42857143      0.08241758 

As a data.frame:

data.frame(slope=coef(lm(game ~ pts*name - pts, data=gamelogs))[3:4])
#                      slope
#pts:nameplayer1 -0.42857143
#pts:nameplayer2  0.08241758

See here for some further explanation of the modelling in the lm call:

https://stat.ethz.ch/R-manual/R-devel/library/stats/html/formula.html
http://faculty.chicagobooth.edu/richard.hahn/teaching/FormulaNotation.pdf#2

In this case pts*name expands to pts + name + pts:name which when removing - pts means it is equivalent to pts:name + name