Exploratory Data Analysis
What EDA Actually Is
Look before you model
A new dataset lands on your desk — three years of retail transactions, say. The temptation is to jump straight to the model or the dashboard. Resist it.
Exploratory data analysis (EDA) is the deliberate first pass: plotting distributions, counting missing values, checking ranges, hunting for surprises. Statistician John Tukey framed it as detective work — you're interviewing the data before you ask it to testify.
Every hour spent exploring saves days downstream: the mislabeled column, the duplicated export, the definition that quietly changed in March — all far cheaper to find now than after you've built on them.
analogy
EDA is the home inspection before the mortgage. Skipping it doesn't save money — it just moves the cost to a worse moment.