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review

Module 02 Self-Test

  1. What's the difference between RANK() and DENSE_RANK() for values [50, 50, 40]?
  2. In Pandas, what does indicator=True add to a merge?
  3. Work through Bayes: disease rate 1/500, test sensitivity 95%, false positive rate 2%. Someone tests positive — what's the probability they're sick? (Do the math.)
  4. OLTP vs OLAP — which uses columnar storage and why?
  5. Why can't you filter a window function directly in WHERE?

Practice Questions

Q: What's the difference between RANK() and DENSE_RANK() for values [50, 50, 40]?
Q: In Pandas, what does indicator=True add to a merge?
Q: Work through Bayes: disease rate 1/500, test sensitivity 95%, false positive rate 2%. Someone tests positive — what's the probability they're sick? (Do the math.)
Q: OLTP vs OLAP — which uses columnar storage and why?
Q: Why can't you filter a window function directly in WHERE?