1.   The Newcastle prescribing index was calculated from item and cost information.

2.   The oral hygiene index was calculated as the sum of the debris and calculus indices.

3.   The cholesterol saturation index was calculated from the tables provided by Carey.

4.   The proliferation index was also calculated separately for each of five compartments of equal size into which each crypt column was divided.

5.   A total labelling index was calculated as the ratio of labelled cell to total cell numbers for each column.

6.   Thirdly, the base figure upon which the index is calculated may be updated.

7.   A dead crow index will be calculated each week for different areas of the city.

8.   A negative reading indicates a slowdown, because the index is calculated by subtracting the percentage of respondents reporting less business from the percentage reporting more.