The Most Prominent Error of 2009

This error stuck out most in the thousands of messages and documents I read in 2009:

Thank you for the booklet, it is very helpful.

Sign up today, the conference will fill quickly.

I saw Grant yesterday, he said to say hello to you.

We decided to buy the unfinished bookshelves, they seemed most economical.

Do you recognize the error?

It is called a run-on sentence, that is, two separate sentences connected by only a comma (not with a conjunction such as and). Run-ons are wrong, even if the two sentences are very short.


Thank you for the very helpful booklet. (OR) Thank you for the booklet, which is very helpful. (OR) Thank you for the booklet. It is very helpful.

Sign up today. The conference will fill quickly. (OR) Sign up today–the conference will fill quickly.

I saw Grant yesterday, and he said to say hello to you. (OR) I saw Grant yesterday. He said to say hello to you.

We decided to buy the unfinished bookshelves because they seemed most economical. (OR) We decided to buy the unfinished bookshelves. They seemed most economical. (OR) Because the unfinished bookshelves seemed most economical, we decided to buy them.

If you know you are guilty of writing run-ons, allow yourself just one idea per sentence. If you do so, you will be able to recognize and correct your run-ons easily. 

When people ask for ways to improve their business writing skills, I suggest eliminating common errors like run-on sentences. Getting rid of those mistakes makes writing instantly stronger.

Syntax Training


  1. Also known as the comma splice, this is one of my chief bug-bears. But I fear we’re fighting a losing battle against it. My prediction is that eventually it will be so common that it’s considered standard English.

  2. Run-on sentences have always looked incorrect to me. I remember being puzzled when covering run-on sentences in 7th grade English class. The teacher was trying to teach us NOT to do something I already KNEW not to do. I felt like I was being asked to eat a spoonful of SAND so I’d know NOT to eat sand.

    Yet I see run-on sentences all the time in the business world, so I’m glad you’re addressing this. Great post!

  3. Hi, Clare. Thank you for reminding me that the error is called a comma splice.

    I don’t think I will every be able to tolerate such sentences– except with “then” in constructions like this one:

    Marcia spoke, then Grace concluded.

    Although it is still a comma splice in my mind, I have seen “then” as a conjunction in non-business writing for years and have gotten used to it.

    Thanks for using the expression “bug-bears.” I can’t wait to look it up to learn its derivation.


  4. Hi, Lester. You are correct, of course, in using the semicolon to connect the two short sentences.

    Although the semicolon is a wonderful punctuation mark when used sparingly, I didn’t recommend it in that structure. I don’t want to encourage its overuse. In business writing classes, I see people inserting a semicolon where a conjunction or a period would clearly be better.

    Were you offering your example as a possibility, or do you really prefer it?

    As always, I appreciate your comment.


  5. Hi, Lynn.

    Thank you for the informative post.

    Run-on sentences also take the prize in Australia for the most common error. In particular, this often occurs with the use of ‘however’.

    For example:

    I have completed the proposal, however I have not submitted it.

    This should be:

    I have completed the proposal. However, I have not submitted it.


    I have completed the proposal; however, I have not submitted it.

    I cover this and other topics on my business writing blog at

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