Final answer:
To resolve their contract dispute without third-party intervention, Shelly and Tom would likely prefer negotiation, which directly involves the two parties communicating to reach an agreement.
Step-by-step explanation:
When Shelly and Tom want to avoid involving third parties in the resolution of their contract dispute, the preferable alternative dispute resolution (ADR) method is negotiation. This approach allows the parties to remain in control of the process and the final decision. Negotiation is an informal process where both sides communicate directly with each other to reach a mutually acceptable agreement. This method contrasts with arbitration, which involves a third-party arbitrator who makes a decision that is usually binding on the parties, and mediation, where a neutral third party helps facilitate a resolution, but does not impose a solution. Lastly, litigation is the most formal and public method, but it involves going to court, which Shelly and Tom wish to avoid.