The phrase "average is based" is correct and usable in written English.
It can be used when discussing how an average is calculated or determined based on certain data or criteria.
Example: "The average is based on the total sum of all values divided by the number of values."
Alternatives: "average relies on" or "average depends on".
There are many variations, depending on the period on which the average is based.
This rises to £18,159 if the average is based on households with some form of unsecured loan.
However, when the observed average is based on a small number of individual user-submitted ratings, the decision-maker may not feel as confident about the product, even when the average is high.
The idea of an ensemble average is based on weather computation forecasting procedures (e.g., Barker 1991; Yamaguchi et al. 2009).
A while back, I alerted you to the fact that the Dow Jones Industrial Average is based on a very oddball formula to determine how much influence each of its 30 component stocks has on the overall index.
The deviation from the average is based on the technical surface of the test specimens and the associated slight change in the wetting properties.
The insurance industry's trade group, America's Health Insurance Plans, said Monday that the 87-cent figure it cited as the industry average was based on information collected by the federal government and was an accurate reflection of how much of each dollar in premiums was spent on medical claims.
This average was based on 42 days.
Each county's daily average was based on measurements from a single monitor or average of data from multiple monitors within the county.
The thickness of tubular epithelium was measured on a line across the apical/basolateral tubular interface, and the average was based on >500 tubules examined per mouse.
When a plant produced less than five fruits or ten seeds, the average was based on the maximum number of fruit or seed produced.
