EMPIRICAL MODELLING
Regression vs Classification
In empirical modelling, we mainly do two kinds of prediction:
- Predicting numerical values
- Predicting by classifying objects or situations
These two ideas lead to regression and classification.
REGRESSION
Predicting a Number
Regression is used when the output is a continuous numerical value.
- Output is continuous
- Decimals are allowed
- The task is about calculating an estimate, not choosing a label
Examples:
- Marks = 72.4
- Temperature = 29.5 °C
- House price = ₹52,40,000
- Distance = 12.3 km
Typical question: How much? How many?
CLASSIFICATION
Predicting a Category
Classification is used when the output belongs to a fixed category.
- Output consists of fixed classes
- Output values are discrete
- Decimals do not apply
- The task is about deciding a label, not calculating a number
Examples:
- Email: Spam or Not Spam
- Student: Pass or Fail
- Disease: Yes or No
- Image: Cat or Dog
- Weather: Hot or Cold
Typical question: Which one? Yes or No?
Conclusion
If the output is a numerical value that can vary continuously, it is a regression problem.
If the output belongs to a fixed set of categories, it is a classification problem.