Check your understanding of this module before moving on.
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Checkpoint quiz 3 questions
A quick check on this module's key ideas before you move on
Question 01
What does stratified sampling guarantee?
B is correct. Stratified sampling keeps each class's share of the data approximately the same in train and test, rather than leaving that to chance.
Question 02
Why does train_test_split shuffle data by default?
B is correct. An unshuffled split could put all early-collected rows in training and all later ones in test, making the split reflect a data-collection difference rather than genuine model quality.
Question 03
When should you switch from a random/stratified split to a chronological split?
B is correct. Time-ordered prediction tasks need a chronological split; otherwise the model can implicitly learn from the future to predict the past, the temporal leakage problem.