In a Michigan small claims court is a written statement by an individual admissible, or must they be there to testify?

A written statement is not admissible, as it cannot be cross examined. You could subpoena them to testify; however, if you are forcing them to come against their will, can you be certain on what they will testify to? You may want to examine the importance of their testimony. Kelly G Lambert III

If it is a written statement by the person you are suing (or who is suing you) than it may be admissible.

A written statement by the other side to the lawsuit is admissible. Under the hearsay rule, other written statements are normally admissible only with the consent of the other side. Michigan Rule of Evidence MRE 803 makes certain other things admissible despite the hearsay rule, such as an "excited utterance," but most of those would not apply to a written document. One thing that might work in some cases is MRE 803(6), Records or Regularly Conducted Activity, such as a financial ledger kept by a business in the ordinary course of business. However, it is possible to avoid the hearsay rule altogether, by arguing MRE 1101(b)(5), which provides that the rules of evidence, except as to privilege, do not apply to small claims court. Try to get a favorable ruling from the judge before taking the risk of showing up with a document instead of a witness. Also, another question to address is how you are going to prove the authenticity of a document without a witness. Anyone can show up at court with a piece of paper saying anything.