Types of Logistic Regression

 

Types of Logistic Regression

Logistic Regression can be categorized based on the type and number of output classes in the problem.


1. Binary Logistic Regression

๐Ÿ”น Definition:

Used when the dependent variable has only two possible outcomes.

๐Ÿ”น Output:

  • 0 or 1
  • Yes / No
  • True / False

๐Ÿ”น Examples:

  • Email classification → Spam / Not Spam
  • Disease detection → Positive / Negative
  • Loan approval → Approved / Rejected

๐Ÿ”น How it works:

  • Predicts the probability of one class
  • Uses a threshold (usually 0.5) to decide the final class

2. Multinomial Logistic Regression

๐Ÿ”น Definition:

Used when there are three or more categories, and no natural order between them.

๐Ÿ”น Output:

  • One class out of many (mutually exclusive)

๐Ÿ”น Examples:

  • Food preference → Veg / Non-Veg / Vegan
  • Handwritten digit recognition → 0–9
  • Type of animal → Dog / Cat / Bird

๐Ÿ”น How it works:

  • Extends binary logistic regression
  • Uses techniques like:
    • Softmax function
    • One-vs-Rest (OvR) classification

3. Ordinal Logistic Regression

๐Ÿ”น Definition:

Used when there are multiple categories with a meaningful order or ranking.

๐Ÿ”น Output:

  • Ordered categories

๐Ÿ”น Examples:

  • Movie ratings → 1 to 5 stars
  • Customer satisfaction → Low / Medium / High
  • Education level → School / College / Graduate

๐Ÿ”น How it works:

  • Considers the order between categories
  • Predicts probabilities while maintaining ranking relationships

๐Ÿ” Quick Comparison

TypeNumber of Classes    Order Matters?    Example
Binary    2    ❌ No    Spam / Not Spam
Multinomial    3+    ❌ No    Food preference
Ordinal    3+    ✅ Yes    Ratings (1–5)

๐Ÿ’ก Key Insight

Choosing the right type depends on:

  • Number of categories
  • Whether those categories have a natural order

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