There are five problems writers sometimes have with comparisons.
1. Make sure you are comparing similar items.
Incorrect: The tusk of a mastodon is bigger than an elephant.
(It sounds as if the writer is comparing the tusk with an elephant.)
Correct: The tusk of a mastodon is bigger than the tusk of an elephant.
2. Make sure your comparison is balanced. Use the same pattern on both sides of the comparison to make it readable and clear.
Unbalanced: The tusk of a mastodon is bigger than an elephant's.
Correct: The tusk of a mastodon is bigger than that of an elephant.
(Or "than the tusk of an elephant"; either choice keeps the pattern of using the prepositional phrase.)
Correct: A mastodon's tusk is bigger than an elephant's.
(Or "than an elephant's tusk"; either choice keeps the pattern of using the possessive noun.)
3. When comparing people or items that are grouped together, it may be necessary to use the word other or else to make the meaning clear.
Incorrect: The X-15 was faster than any airplane.
(The X-15 is an airplane. The sentence makes it sound as though it were some other kind of aircraft.)
Correct: The X-15 was faster than any other airplane.
Incorrect: Manute was taller than anyone on the team.
(This suggests that he either was not on the team or that he is being compared to himself.)
Correct: Manute was taller than anyone else on the team.
4. The words major and minor are comparative forms that have lost some of their original usage. However, it is nonstandard to add -ly to them just as it is to add -ly to any comparative adjective or adverb that ends in -er.
Incorrect: He was majorly disappointed.
Correct: He was greatly disappointed.
Correct: He was more greatly disappointed than we thought.
5. Avoid the double comparison. Words that end in -er or -est and certain irregular comparisons do not need to be modified with the words more, most, less, or least since they are already comparative or superlative.
Similarly, do not add an -er or -est to an irregular comparison for the same reason.
Incorrect: That film was more funnier than the one we saw last week.
Correct: That film was funnier than the one we saw last week.
Incorrect: She felt worser yesterday. (Worse is already comparative.)
Correct: She felt worse yesterday.
The word lesser is accepted by most authorities when used as an adjective meaning smaller or less significant.