coefficient of variation given the number of years 𝐶𝑉𝑡 = 𝑆𝐷𝑡 ̅̅̅̅ 𝑅𝐹𝑡 where 𝑆𝐷𝑡 is the standard deviation while the seasonality index takes on Walsh and Lawler’s (1981) measure 12 ̅̅̅̅1|𝑦 𝑅𝐹 1 𝑆𝐼𝑦 = | ∑ |𝑅𝐹𝑖|𝑦 − ̅̅̅̅1|𝑦 12 𝑅𝐹 𝑖=1 ̅̅̅̅1|𝑦 is the average for the year and 𝑅𝐹𝑖|𝑦 is the value of rainfall on the ith month. That is, for a given year y, 𝑅𝐹 The seasonality measure for a collection of years 𝑦 is the average of all seasonality indices across those years, 𝑦𝑛(𝑦) 1 𝑆𝐼𝑦 = ∑ 𝑆𝐼𝑦 𝑛(𝑦) 𝑖=𝑦1 The seasonality index facilitates measurement of the variability of rainfall in terms of seasonality over the year. Sumner, et al (2001) provides indicative classification based on 𝑆𝐼𝑦 as shown in Table 5. Table 5. Rainfall seasonality based on 𝑺𝑰𝒚 <0.19 0.20–0.39 0.40–0.59 0.60–0.79 0.80–0.99 1.00–1.19 >1.20 Precipitation spread throughout the year Precipitation spread throughout the year, but with a definite wetter season Rather seasonal with a short drier season Seasonal Markedly seasonal with a long dry season Most precipitation in <3 months Extreme seasonality, with almost all precipitation in 1–2 months Given the aforementioned formulas, the climate shocks are measured through change in each climate variable for each year compared to long run average which is set as 1979-2006. These were computed using the following: 1. Change in current year average rainfall to long run average in 1979-2006: 𝑑𝑅𝐹𝑦 = 100 ( ̅̅̅̅ 𝑅𝐹1|𝑦 ̅̅̅̅ 𝑅𝐹28|1979−2006 − 1) 2. Change in current year rainfall seasonality relative to long run seasonality in 1979-2006: CBMS-FAO | 25