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Pruning decision tree #80

Closed Cindyyyhey closed 4 years ago

Cindyyyhey commented 4 years ago

Hi Professor McGowan,

I'm having trouble understanding this pruning equation. What is Yi? What does the Rm(box, predictor space) mean? Are we using this equation to find an ideal alpha? Or we use cross validation to get alpha first, then fit in to this equation. How much do we need to understand this equation for midterm 3? Thanks in advance! 屏幕快照 2020-04-21 下午8 21 04

LucyMcGowan commented 4 years ago

yi is the observed outcome
Rm is the box that corresponds to the mth terminal node: here is a visual of the box from the slides: https://sta-363-s20.lucymcgowan.com/slides/16-decision-trees-reg.html#17
you are using cross validation to get alpha

Cindyyyhey commented 4 years ago

Got it, thank you!