Writing & Grammar: Compound Sentences and Run-Ons

by Jennie Ruby 

Putting two sentences together to form one larger sentence is a common way to express more complex thoughts. But I see even academic writers with MAs or PhDs get the punctuation wrong. Here's how it works. You put two complete sentences together.

Nothing is more central to neoclassical microeconomics than the concept of a market.

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Textbooks leave its meaning up in the air.

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The asterisk indicates where the two original sentences meet. The three most common ways to correctly negotiate this meeting spot are as follows:

Add a comma plus a conjunction (but, or, yet, for, and, nor, so)

Add a semicolon alone

Add a semicolon plus a transition word (however, therefore, hence, etc.) followed by a comma

Although there are some circumstances where a colon or a dash can work well, these three are the most frequent correct methods. Failure to use sufficient punctuation between two sentences combined into one creates an error called a "run-on sentence."

Challenge: Correct these run-on sentences from the technical field of economics using the three methods described above. Please send your answers to me when ready.

1. Perfect markets are not at all proxies for real markets, they suppose an institutional form opposed to the idea of a market.
2. Preference orderings and endowments are a good abstraction of consumers production sets and they give an idea of the level of technology use within a firm.
3. There is no relation, let alone identity, between individual and collective behavior, this has been philosophically acknowledged since ancient times.
4. The methodological implications of differing definitions of economic processes are quite drastic, long-term investment cannot be determined in an acceptably meaningful manner because the system is subjected neither to the rules of competition nor to the optimizing behavior of cooperative arrangments.
5. The moment a macro-system is broken up into subsectors it no longer holds together it cannot be built from the bottom up either.

Last Week Answers

The answers this week are brought to you by Phil Eschtruth Harrison.

1. If you need to file a claim (even during nonbusiness hours, when we are not available), submit the form by fax or online. [Removed comma after "available".]
2. Please verify your address (our database needs to be updated). [Moved comma outside closing parenthesis.] Or, another option would be to make it a separate sentence like this: Please verify your address. (Our database needs to be updated.)
3. It is extremely important that all of your membership data is verified before the end of the month (when we finalize our billing). [Removed extra period after word "billing".]
4. Use our paperless option (it's easy, we swear!), and we'll give you a credit to use in our online store.[Removed comma before the parentheses.]
5. Choose the Internet speed that's perfect for your needs. (We offer four different speed and price options.) [Added a period after "needs" to make it two separate sentences.]
6. Our network is 99.9% reliable (even during extreme weather events). [Moved period outside the closing parenthesis.]

By far the hardest item was number 4, with 25 percent of respondents getting something wrong–usually removing the comma after the parenthesis. This sentence is actually two complete independent clauses, so a comma is needed, along with the word and, to separate them. Although extremely short sentences can be combined with a conjunction alone, the parenthetical element adds enough complexity that I think the comma is required. One respondent removed the exclamation point, but that is not required.