Contents
Why Statistics Sits at the Heart of Data Science
People often picture data science as machine learning and code. Underneath, almost every step leans on statistics, the practice of collecting, summarizing and interpreting data so that decisions rest on evidence instead of hunches.
Where it shows up
Before training a model, someone has to ask whether the data is clean, whether it reflects the real world, and what its typical values look like. Those are statistical questions.
After training, someone has to decide whether a 2% accuracy gain is a genuine improvement or just luck. Also statistical.
Two jobs statistics does
Descriptive statistics summarises the data you already have through averages, spreads and charts. Inferential statistics goes a step further, using a smaller data set to draw conclusions about something bigger, like predicting how millions of users will behave from a few thousand.
Why not just trust the algorithm?
A model will produce an answer from almost any data you hand it, including flawed data. Statistics gives you the habits and tools to notice when an answer shouldn’t be trusted, and that skill separates a data scientist from someone who only runs code.
Probability and Statistics for Data Science
Abhishek Pati








