error來自bias 和variance
PARRELLEL UNIVERSE
假定每個(gè)平行宇宙里的我抓了十個(gè)不同的寶可夢(mèng)
越復(fù)雜的model受data影響越大憨募。
underfiting:not fitting the training examples
overfitting:large error on testing data
large bias:redesign? the model:add more features as input/a more complex model
large variance:more data/regularization(可能傷害bias)
MODEL SELECTION
NOT do: