Review Question - QID 103886

The mean (8), median (7), and mode (9) of a set of observations are the average, middle, and most common observations, respectively.

This case series has a sample size of 11 children. The mean, median, and mode are all measures of central tendency and are used to succinctly convey to the reader a typical expected value of the data. The mean is the average of the observations, mean = (7+9+6+13+9+5+5+6+7+12+9)/11 = 8. The median is the middle value if the observations are all ordered from smallest to largest, median = 5, 5, 6, 6, 7, (7), 9, 9, 9, 12, 13. The mode is simply the most common value. In this dataset, 3 children experienced symptoms for 9 days, more than any other duration.

Rosner, defines the mean: (sum of all observations)/sample size. Likewise, the sample median can also be more formally defined as follows: 1) If the sample size is odd, the median = ((sample size+1)/2)th largest value. 2) If the sample size is even, the median = the average of the (n/2)th and ((n/2)+1)th largest values. This dataset has 11 values and thus the first equation yields that the median is the (11+1)/2 = 6th largest observation = 7 days.

Incorrect Answers:
Answer 2-4: At least one of the descriptive statistics has been calculated incorrectly.
Answer 5: Enough information is provided in Figure A to determine the mean, median, and mode.