This study examines the phonetic realizations of English word stress to identify the influence of experiment method on experiment results. Stimuli uttered by native and Korean ESL beginners in authentic conversations are extracted to be shuffled according to their positions in utterances and information structure. Results indicate that the acoustic characteristics of English word stress are realized depending on its position in utterances. The native speakers correlate the stressed syllables in shorter duration with higher pitch and stronger intensity at sentence-final positions unlike the previous experiments and the traditional definition that stressed syllables are uttered in longer duration with higher pitch and stronger intensity; at sentence-medial positions, the native speakers correlate the stressed syllables in longer duration with higher pitch and no regularity in intensity or in shorter duration with lower pitch and intensity depending on their conversational intention. Korean ESL beginners correlate the stressed syllables in shorter duration regardless of positions in sentences with no regularity in pitch and intensity. This study, thus, shows that a different experiment method may result in different results on the phonetic realizations of English word stress.