Beginner
Statistics for data science – interview notes
1. When is the median better than the mean?
When the data is skewed or has outliers, e.g. salaries or house prices.
2. What is a p-value?
The probability of seeing a result at least this extreme if the null hypothesis were true. It is not the probability that the hypothesis is true.
3. How do you design an A/B test?
Pick one metric, estimate sample size up front, randomise users, run for full business cycles and avoid peeking early.
4. Correlation vs causation?
Correlation means two things move together; causation means one changes the other. Only a controlled experiment (or careful causal methods) shows causation.
Feedback & comments (2)
Vikram Singh
Great summary. It would be nice to add one more example with real data.
Sneha Iyer
Exactly what I needed for my placement preparation.