Interview Q&A / Data Science
Data Science interview questions
Statistics, pandas, cleaning data and exploratory analysis for analyst and data science roles.
Prefer rapid revision? Practise Data Science short interview answers →
- How does a two-sample t-test work? Walk through a small example.
It tests whether two group means differ by more than chance would explain. The t statistic is the difference in means divided by its standard error; a large |t| gives a small p-value and evidence against equal means.
IntermediateQuick answer1 min read - What is the difference between a one-tailed and a two-tailed test?
A two-tailed test looks for a difference in either direction; a one-tailed test looks only for an increase or only for a decrease. The one-tailed p-value is half the two-tailed one, so the direction must be decided before seeing data.
IntermediateQuick answer1 min read - When do you use a paired t-test instead of an independent t-test?
Use a paired t-test when the two measurements come from the same subjects or matched pairs, such as before and after. It tests whether the mean of the differences is zero, which removes person-to-person variation.
IntermediateQuick answer1 min read