Human factors play an important role in the applications of speech technology. Ina Wizard of Oz experiment, 64 telephonic inquiry systems were simulated by systematic manipulation of 6 human factors. To assess the impact of those factors on the appreciation, an appreciation scale was developed based on an questionnaire. In an experiment 414 respondents were requested to call one of the simulated systems and a system operated by human operators. The respondents rated these systems on an appreciation scale. In this paper a description of the experiment is given and the results of a statistical analysis of the appreciation scores is presented.