Table 3: Volume changes from 2017/18 to 2019/20

_{Source: NHS Prescription Services “Dispensing Doctors Report” and “Personal Administration Report” at  https://www.nhsbsa.nhs.uk/prescription-data/dispensing-data/pd1-reports. Total number of prescriptions is the total in column D of each year from the Statistical Data Relating to Personal Administration Claims by Prescribing Doctors added to the totals A & B & C in column E for the Statistical Data Relating to Prescriptions Dispensed by Dispensing Doctors}

Historical average annual volume change over last two years

Formula to calculate average percentage change over last two years is:

Total fees for 1st year x (1 + A) ² = Total fees for the third year
 

Where A = annual percentage increase/decrease

84,862,375 x   (1 + A) ²           = 86,841,867

(1 + A) ²       = 86,841,867 / 84,862,375 

(1 + A) ²       = 1.0233

(1 + A)        = √1.0233               

(1 + A)         = 1.0116

A                  = 1.0116 - 1

Therefore A                             = 0.0116

Average volume change over 2 years                                   = 1.160 per cent  

^{Note: The Geometric Mean has been used to calculate the average percentage change in fees. The Geometric Mean is a measure of the average value of a set of numbers by using the product of their values (as opposed to the arithmetic mean which uses their sum), and is calculated by multiplying all values together where n is the count of the number of values and then calculating the nth root.}