Classification vs Regression

Why they differ

Classification picks one group from a fixed list; regression gives a number on a scale, such as a price or a time.

Machine learning basics

Teaching a computer to sort each new case into one of a fixed set of groups, such as approve or reject, or real attack or false alarm.

Formal

A task in machine learning where the model learns from labelled examples to give each new input one label from a known, fixed list, often together with a score for how sure it is.

In plain English

Like a coin-sorting machine at a bank; every coin drops into the slot for its value, and there is no slot for a coin it has never seen.

In practice

At a shipping company, a model trained on thousands of invoices a bookkeeper had already sorted puts each new invoice into one of 40 cost types, such as fuel or harbour fees, and sends the unsure ones back to her.

Why it matters

No model sorts every case right, and wrong calls differ in cost (a missed attack usually costs more than a false alarm), so someone must decide which mistakes to accept and where a person checks.

Regression

Machine learning basics

Teaching a computer to guess a number on a scale, such as a price, a time or a size, from past examples where the real number was known.

Formal

A task in machine learning where the model learns from labelled examples to map an input to a number that can take any value within a range, and is judged by how far its guesses land from the real values.

In plain English

Like guessing a house's price from its size, age and street after seeing what many other houses sold for; the answer is an amount, not a yes or no.

In practice

An operations planner at a water utility uses a model trained on five years of readings to predict tomorrow's water use hour by hour from the weather forecast and the day of the week.

Why it matters

Many business questions are "how much" or "how long", not "which one"; the guess always has a margin of error that must be shown, not hidden.

Shared connections

Decision tree Supervised learning