Technically an average is general statistic and mean and median (as well as mode) are specific types of averages. As a person with a stats background I often us

Technically an average is general statistic and mean and median (as well as mode) are specific types of averages. As a person with a stats background I often use "average" to mean the general concept instead of a strict arithmetic mean. It was easy to figure out what the author meant, and his point should be taken for what he meant: half of people are below median.