How is the New : Review ratio calculated?

This is calculated by the sum of all review appointments that happened during the timeframe (e.g.26 weeks), divided by the sum of all new appointments that happened during the timeframe (e.g. 26 weeks).

Hence, it calculates the New : Review ratio for the 26 weeks’ time period activities, which is different to the average value of the weekly N:R ratio over the 26 weeks’ time.