USMLE – Reasoning Ability
Topic: Analogy
Analogy is a reasoning skill that tests the ability to recognize a relationship between two items and apply that same relationship to a new pair.
In the USMLE (and other competitive exams like the JEE), analogy questions appear in the Analogy section of the Reasoning Ability/Quantitative Aptitude tests.
1. What is an Analogy?
| Symbol | Meaning |
|---|---|
| X : Y :: A : B | “X is to Y what A is to B.” |
| X ↔ Y | “X corresponds to Y.” |
Goal: Find B so that the relationship between X and Y is replicated by A and B.
2. Types of Analogies
| Category | Example | Typical Reasoning |
|---|---|---|
| Synonym / Antonym | Happy : Sad :: Brave : ___ | Identify the opposite of “Brave.” |
| Part‑Whole / Whole‑Part | Wheel : Car :: Finger : ___ | A wheel is part of a car → finger is part of a hand. |
| Function / Tool | Scalpel : Surgeon :: Microscope : ___ | A scalpel is used by a surgeon → microscope is used by a biologist. |
| Cause‑Effect | Smoking : Cancer :: Alcohol : ___ | Smoking causes cancer → alcohol causes… |
| Process‑Result | Heat : Melt :: Light : ___ | Heat causes melting → light causes… |
| Attribute‑Attribute | Tall : Short :: Heavy : ___ | Height is opposite of… |
| Category‑Member | Bird : Sparrow :: Mammal : ___ | Bird is a category → sparrow is a member. |
| Degree‑Degree | Small : Tiny :: Large : ___ | Tiny is to small as ___ is to large. |
| Location / Direction | Top : Bottom :: Left : ___ | Opposite of left is right. |
| Temporal | Morning : Day :: Night : ___ | Night is to day as… |
| Similarity | Apple : Fruit :: Carrot : ___ | Apple is a type of fruit → carrot is a type of vegetable. |
Tip: When in doubt, look for the most basic relation (e.g., “part–whole” often shows up in medical analogies).
3. Step‑by‑Step Strategy
| Step | What to Do | Why |
|---|---|---|
| 1. Parse the pair | Identify the relation (synonym, antonym, part‑whole, etc.). | Avoid mis‑reading. |
| 2. List all possible relations | Write down potential relationships for the given pair. | Helps in cross‑checking. |
| 3. Apply the same relation | Transfer the identified relation to the second pair. | Core of analogy solving. |
| 4. Eliminate incorrect options | Use elimination logic (e.g., wrong part‑whole or wrong antonym). | Reduces the answer space. |
| 5. Verify | Ensure both sides exactly mirror each other. | Prevents subtle mis‑match. |
| 6. Double‑check for “best fit” | If more than one option fits, choose the most natural analogy. | Medical analogies usually prefer anatomical or physiological terms. |
4. Common Pitfalls
| Pitfall | How to Avoid |
|---|---|
| Assuming synonyms are always antonyms | Verify with context. |
| Misreading “part‑whole” as “whole‑part” | Check direction: Wheel : Car → Finger : Hand. |
| Choosing a relationship that fits only one pair | Both pairs must share the same relationship. |
| Over‑complicating | Stick to the simplest relation first. |
| Ignoring “non‑obvious” relations | Take a breath; sometimes the answer is a process‑result or tool‑user. |
5. Practice: Hard Analogy Question
Question:
“Suture : Wound :: Scalpel : ___”Choose the correct answer:
- Surgeon
- Incision
- Tissue
- Hemostasis
Solution
-
Identify the relation
Suture is used to close a wound → Suture is a tool → Wound is the object that is closed. -
Apply to the second pair
Scalpel is a tool → What does it do? It creates an incision in the tissue.
So the relation is tool → object it acts upon. -
Match options
- Surgeon (user of the scalpel) – wrong direction.
- Incision – the object the scalpel acts on. ✔️
- Tissue – the substrate; but scalpel acts on tissue, not creates it.
- Hemostasis – a consequence, not the direct object.
Answer: 2. Incision
6. Summary of Key Points
- Analogy tests relational thinking: X relates to Y → A relates to B.
- Common relations: synonym/antonym, part‑whole, tool‑user, cause‑effect, etc.
- Strategy: identify relation, apply, eliminate, verify.
- Pitfalls: wrong direction, over‑complication, ignoring simple relations.
- USMLE Tip: Clinical analogies often involve anatomical parts, diagnostic tools, pharmacologic actions; look for those patterns.
7. Hard Practice Question (for self‑assessment)
“Antibiotic : Infected Cell :: Antibody : ___”
A) Virus
B) Antigen
C) Bacterium
D) White Blood Cell
**Answer & Explanation