This paper discusses an experiment series in the course of which so-called simulated dialogues in Estonian were collected in human-computer interaction. The subjects were asked to test a program, which interacted with a person in written Estonian, which gave information about cinema, TV listings, weather, politics or flights. In reality another person (so-called Wizard of Oz) answered the subject's questions via Internet. I will introduce the Wizard of Oz interface. All the experiments have been recorded in a log file; on the basis of this information the analysis of dialogues takes place. I primarily concentrate on a repair type occurred in dialogues, which based on the conversational analysis is called other-initiated repair. I look for language rules (patterns) which have been followed to produce the utterances. This research is one step closer to the aim to create a computer program, which provides users with the information in the most convenient and pleasant way.