Interview Q&A / Data Science
Data Science interview questions
Statistics, pandas, cleaning data and exploratory analysis for analyst and data science roles.
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- What is the coefficient of variation, and when is it useful?
The coefficient of variation is standard deviation divided by mean, often shown as a percentage. It measures relative spread, so you can compare variability between datasets with different units or very different averages.
IntermediateQuick answer1 min read - Why do we divide by n-1 when computing sample variance?
A sample sits closer to its own mean than to the true population mean, so dividing by n underestimates the population variance. Dividing by n-1 (Bessel correction) removes that bias on average.
IntermediateQuick answer1 min read