Section 9.9 Common Errors: Comma Splices and Run-Ons
Two of the most common sentence-level errors in academic writing both involve connecting independent clauses without sufficient punctuation. These errors are not just minor style issues—they mislead readers about clause boundaries and can obscure the logical relationship between ideas. A comma splice and a run-on sentence are easy to produce and easy to fix once you understand what they are and why they violate the grammar of compound sentences.
Comma Splices.
A comma splice joins two independent clauses with only a comma (no conjunction):
Fixes:
-
Add conjunction: The concert ended, and the crowd cheered.
-
Use semicolon: The concert ended; the crowd cheered.
-
Make two sentences: The concert ended. The crowd cheered.
-
Subordinate: When the concert ended, the crowd cheered.
Run-On Sentences (Fused Sentences).
A run-on sentence joins independent clauses with no punctuation:
Fixes: Same as comma splices.
