A psychologist investigates the effects of sleep deprivation on cognitive performance by measuring the reaction times (in milliseconds) of 7 participants. The recorded times are: 240,245,250,255,260,265, 240, 245, 250, 255, 260, 265,\,240,245,250,255,260,265, and 890.
Which measure of central tendency is the most appropriate for summarizing this dataset, and what is its value?
The mean, because it is the most sensitive measure of central tendency, giving a value of 343.6 ms343.6\text{ ms}343.6 ms.
The median, because it is unaffected by the extreme outlier of 890 ms890\text{ ms}890 ms, giving a value of 255 ms255\text{ ms}255 ms.
The median, because excluding the extreme outlier of 890 ms890\text{ ms}890 ms yields a more typical middle value of 252.5 ms252.5\text{ ms}252.5 ms.
The mode, because it represents the most frequently occurring range of reaction times, giving a value of 250 ms250\text{ ms}250 ms.
513 exam-style questions on OCR A Level Psychology Data recording, analysis and presentation. Each one has a worked solution and a mark scheme showing where the marks go.