Ohio Rev. Code § 2712.12
An arbitration agreement may be in the form of an arbitration clause in a contract or in the form of a separate agreement. An arbitration agreement shall be in writing. An agreement is in writing if it is contained in a document signed by the parties or in an exchange of letters, telex, telegrams, or other means of telecommunications that provide a record of the agreement, or in an exchange of statements of claims and defenses in which the existence of an agreement is alleged by one party and not denied by another. The reference in a contract to a document containing an arbitration clause constitutes an arbitration agreement provided that the contract is in writing and the reference is such as to make that clause part of the contract.
R.C. §2712.12