To determine which measure of central tendency is the middle value in a set of ordered data, we need to understand the definitions of the different measures of central tendency:
- Mode: The mode is the value that appears most frequently in a data set. A data set may have one mode, more than one mode, or no mode at all if no number repeats.
- Median: The median is the middle value of a data set when the values are arranged in ascending or descending order. If the number of observations is odd, the median is the middle number. If the number of observations is even, the median is the average of the two middle numbers.
- Mean: The mean, or arithmetic average, is found by adding up all the values in a data set and dividing by the number of values.
Based on the definitions above, the measure of central tendency that represents the middle value in a set of ordered data is the median.
Hence, the correct answer is:
OB. Median.