A researcher interested in observing sleep patterns asks people to come into her sleep laboratory so that their sleep behaviour can be systematically monitored.One of the things she is interested in is the relationship between the number of times a person rolls over in the night and their ability to perform a range of cognitive tasks the following day.If the shaded bars in the graph below represent the number of times a sample of 25 people roll over in the night, which of the following statements is true?
A)The distribution of number of rolls is negatively skewed.
B)The modal number of rolls is 3.
C)The mean number of rolls is 2.
D)The median number of rolls is 2.
E)The mean is probably the most appropriate measure of central tendency.

Question

A researcher interested in observing sleep patterns asks people to come into her sleep laboratory so that their sleep behaviour can be systematically monitored.One of the things she is interested in is the relationship between the number of times a person rolls over in the night and their ability to perform a range of cognitive tasks the following day.If the shaded bars in the graph below represent the number of times a sample of 25 people roll over in the night, which of the following statements is true? 
A)The distribution of number of rolls is negatively skewed. 
B)The modal number of rolls is 3. 
C)The mean number of rolls is 2. 
D)The median number of rolls is 2. 
E)The mean is probably the most appropriate measure of central tendency.

Quizplus · Accepted Answer

The median would be the most appropriate measure of central tendency because the distribution is likely to be positively skewed, with a few individuals having a high number of rolls in the night. The mode cannot be determined from the graph because no bar is taller than the others. The mean cannot be determined from the graph and is not likely to be the most appropriate measure of central tendency because it could be influenced by outliers (i.e., individuals who roll over many times).

A Researcher Interested in Observing Sleep Patterns Asks People to Come