Author
Alon Halevy, Peter Norvig, Fernando Pereira
1 reading card from 1 book · 2009.
1 card
The Unreasonable Effectiveness of Data · 2009
A feature is computed "as it was at the time of the event", not "as it is now".
The 2009 argument became doctrine: more data beats a cleverer model. The unspoken condition is that the data is correct in three ways a reporting warehouse does not demand. First, point-in-time correctness: a feature is computed "as it was at the time of the event", not "as it is now" — a customer who is premium today may have been on the free tier when they placed the 2023 order; type 2 dimensions are exactly the tool here. Then, leakage: a column that contains the answer, directly or indirectly — the cancellation date when predicting cancellation; the model looks excellent in training and fails in production. Finally, training–serving skew: the features computed in batch for training and those computed live for prediction must come from the same code; the feature store exists to guarantee that. The rest is warehouse discipline: split sets by time, not at random; document the label definition; version the training set so you can reproduce it a year later; keep class balance in mind. Only then does "a lot of data" mean more than "a lot of rows".
“But invariably, simple models and a lot of data trump more elaborate models based on less data.”