Comparison Errors in Sentence Correction: Types and Fixes

Comparison errors are among the most reliably tested grammar traps in placement aptitude verbal sections. They read naturally at first glance; the error only surfaces when you break the sentence into its grammatical parts.

Sentence correction questions in AMCAT English, TCS NQT verbal, and Deloitte verbal rounds regularly include sentences where a comparison goes wrong in one of five ways. Each error type has a single correction rule. Learn the rule and you can handle any variant of that pattern under test conditions.

What Makes a Comparison Grammatically Correct

A valid comparison satisfies four conditions:

• Complete: both terms being compared are stated explicitly.
• Logical: the compared items belong to the same category (price compared to price, not price to company).
• Correct in form: comparative adjectives (-er, more) for two items; superlative (-est, most) for three or more; “than” for inequality; “as…as” for equality.
• Parallel: both sides of the comparison use the same grammatical structure.

When any one of these conditions fails, the sentence has a comparison error.

Error Type 1: Incomplete Comparison

An incomplete comparison leaves out one side of what is being compared, making the sentence ambiguous or meaningless.

• Original: The price of this laptop is lower.

• Error type: Incomplete comparison. No reference point is stated.

• Correction rule: State both terms explicitly. What is the price being compared to?

• Corrected: The price of this laptop is lower than that of the previous model.

• Original: She scored better on the exam.

• Error type: Incomplete comparison. Better than what, or better than whom?

• Correction rule: Complete the comparison by naming the reference.

• Corrected: She scored better on the exam than her classmates did.

Error Type 2: Illogical Comparison

An illogical comparison matches an attribute of one thing against the entire object of another, instead of matching like attributes to like attributes.

• Original: The salary at Company X is higher than Company Y.

• Error type: Illogical comparison. Salary (an attribute) is compared to Company Y (an entity).

• Correction rule: Compare salary to salary. Use “that at” as a stand-in for “the salary at”.

• Corrected: The salary at Company X is higher than that at Company Y.

• Original: The population of Mumbai is greater than Delhi.

• Error type: Illogical comparison. Population (a count) is compared to Delhi (a city).

• Correction rule: Use “that of” to stand in for “the population of”.

• Corrected: The population of Mumbai is greater than that of Delhi.

Error Type 3: Misuse of “Than” and “As…As”

“Than” signals that one item exceeds or falls short of another. “As…as” signals equality. Using one where the other is required changes the meaning entirely.

According to Purdue OWL’s guide on comparative and superlative adjectives, this is one of the most commonly misapplied comparison rules in formal written English.

• Original: She is taller as her brother.

• Error type: “As” used where “than” is required after a comparative adjective.

• Correction rule: Comparative adjectives (taller, faster, smarter) take “than”.

• Corrected: She is taller than her brother.

• Original: He is as experienced than his colleague.

• Error type: “Than” used inside an “as…as” equality structure.

• Correction rule: The “as…as” pattern requires a second “as”, not “than”.

• Corrected: He is as experienced as his colleague.

Error Type 4: Comparative vs. Superlative Form

Comparative forms (-er, more) compare exactly two items. Superlative forms (-est, most) identify the extreme within a group of three or more items. Swapping them is a frequent test trap.

• Original: Between these two laptops, this one is the best.

• Error type: Superlative (“best”) used when comparing only two items.

• Correction rule: Two items call for a comparative form (“better”).

• Corrected: Between these two laptops, this one is the better.

• Original: Of all the students in the class, Priya is the more diligent.

• Error type: Comparative (“more diligent”) used when comparing within a group of more than two.

• Correction rule: Three or more items call for a superlative form (“most diligent”).

• Corrected: Of all the students in the class, Priya is the most diligent.

Error Type 5: Non-Parallel Structure

Both sides of a comparison must use the same grammatical form. Mixing a gerund on one side with an infinitive on the other breaks parallelism.

• Original: She enjoys swimming more than to run.

• Error type: Non-parallel structure. Gerund (“swimming”) on the left, infinitive (“to run”) on the right.

• Correction rule: Match the forms. If the first verb is a gerund, the second must be too.

• Corrected: She enjoys swimming more than running.

• Original: I prefer watching films to go to the theatre.

• Error type: Non-parallel structure. Gerund (“watching”) paired with an infinitive (“to go”).

• Correction rule: With “prefer…to”, both sides should use gerunds.

• Corrected: I prefer watching films to going to the theatre.

Two Additional Patterns

Placement tests occasionally include two further comparison traps that fall outside the five types above.

Double Comparison

A double comparison applies both the inflected form and “more” to the same adjective, creating redundancy.

• Original: This route is more faster than the highway.
• Error type: Double comparison. Both “-er” and “more” applied to “fast”.
• Correction rule: Use one mechanism only. Standard English uses “faster”, not “more fast”.
• Corrected: This route is faster than the highway.

Omitting “Other” in Self-Inclusive Comparisons

When a subject is compared against every other member of its own group, omitting “other” creates a logical contradiction: the subject ends up being compared to itself.

• Original: Ramesh is more dedicated than any student in the department.
• Error type: Self-inclusive comparison. “Any student” includes Ramesh himself.
• Correction rule: Add “other” to exclude the subject from the comparison group.
• Corrected: Ramesh is more dedicated than any other student in the department.

Quick Reference: Error Types at a Glance

Error Type	Trigger Pattern	Fix
Incomplete comparison	”X is lower / better” with no reference term	Add the reference term
Illogical comparison	”salary at A higher than B (entity)"	"higher than that at B” or “than salary at B”
Wrong than/as	”taller as” or “as X than"	"taller than” / “as X as”
Wrong form (two vs. three+)	“the best of the two"	"better” for two; “best” for three or more
Non-parallel structure	”swimming more than to run”	Match grammatical forms on both sides
Double comparison	”more faster”, “more better”	One mechanism only: “faster”, “better”
Missing “other"	"more X than any student” (self-inclusive)	“more X than any other student”

How These Errors Appear on Placement Tests

Sentence correction questions in verbal aptitude tests present a sentence and ask you to identify the error or select the correct replacement. The strategy is consistent across AMCAT, TCS NQT, and IBM verbal assessments: when you spot a comparison, check all four conditions in order. Completeness first, logical comparability second, then the than/as choice, and finally parallel structure. Most errors fail only one of these checks; the correct option fixes exactly that failure and no other.

For a broader view of how sentence correction fits into the verbal module alongside vocabulary and reading comprehension, the aptitude test preparation guide for engineering placements maps the four aptitude sections together.

Recognising illogical and non-parallel comparisons on an aptitude test sharpens the same analytical attention you need to evaluate AI-generated text critically. The “more better” double comparison and the “salary vs. company” illogical comparison both pass unnoticed in AI output unless you check for them. TinkerLLM starts at ₹299 and gives you a hands-on environment to work with real LLM outputs, which turns placement-prep precision into a skill that transfers to AI-era work.