Final answer:
When calculating the middle value of a data field in a data set, you are calculating the median.
Step-by-step explanation:
The middle value of a data field in a data set is calculated by finding the median. The median is the value that separates the data set into two equal parts. When the data set has an odd number of values, the median is the middle value. When the data set has an even number of values, the median is the average of the two middle values.
For example, let's say we have the following data set: 2, 4, 6, 8, 10. The median of this data set is 6 because it is the middle value. If we have the following data set: 2, 4, 6, 8, 10, 12, the median is calculated by taking the average of the two middle values: (6 + 8) / 2 = 7.