Comma splice = two sentences separated by a comma
Rule = comma splices are always wrong
The comma splice is one of the most frequently tested errors on both SAT Writing and ACT English. Comma splices trump all other stylistic issues, which means that no matter how good a sentence sounds otherwise, it cannot be correct if it contains one.
Note that the most common tip-off for this error is “comma + pronoun” (he, she, it, they).
Comma Splice: Anna Robertson (“Grandma”) Moses only began painting at the age of 78, she achieved fame as an artist.
The four most common ways to fix comma splices are as follows:
1) Add a coordinating conjunction after the comma
Coordinating Conjunctions: For, And, Nor, But, Or, Yet, So
Correct: Anna Robertson (“Grandma”) Moses only began painting at the age of 78, but she achieved fame as an artist.
2) Replace the comma with a period or semicolon
A period/semicolon can be added alone or, more commonly, a conjunctive adverb (however, therefore, nevertheless, moreover) can be placed after the period or semicolon in order to make the relationship between the clauses clear.
Correct: Anna Robertson (“Grandma”) Moses only began painting at the age of 78; she achieved fame as an artist.
Correct: Anna Robertson (“Grandma”) Moses only began painting at the age of 78; nevertheless, she achieved fame as an artist.
Correct: Anna Robertson (“Grandma”) Moses only began painting at the age of 78. However, she achieved fame as an artist.
3) Make one of the clauses dependent by adding a subordinating conjunction (although, because, while)
Correct: Although Anna Robertson (“Grandma”) Moses only began painting at the age of 78, she achieved fame as an artist.
4) Add a participle
Correct: Anna Robertson (“Grandma”) Moses only began painting at the age of 78, achieving fame as an artist.
Tip: whenever you see answer choices that include a semicolon, a period, and a comma + and/but, you can automatically eliminate all of those options. They are exactly equivalent to one another, and you will never be asked to choose between two equally correct answers.