In his master’s thesis, Richard Dreyson set out to test the hypothesis that Singaporean speakers of English prefer the British accent of English to the Australian, American, and Singaporean accents of English. Dreyson recorded a British speaker, an Australian speaker, an American speaker, and a Singaporean speaker talking about a personal experience of theirs. These (audio) recordings were then played to a hundred university students at NUS. The students were asked to rate the appeal of the four speakers on a scale ranging from one (extreme disapproval) to ten (extreme approval). Dreyson found that the British speaker got the highest rating. He concluded from this fact that speakers of English in Singapore prefer the British accent to the Australian, American, and Singaporean accents. Now, Dreyson's supervisor was very unhappy about the way Dreyson had conducted his research, and therefore asked him to re-do the entire experiment with an improved design.

Task: Identify the defect(s) in Dreyson's research design and suggest a way of redesigning the experiment so that this/these defect(s) would be remedied.