agricultural inputs (as estimated from field surveys or obtained from historical price hike data), (iii) changes in on‐farm labor market and (iv) changes in other sources of income/food to estimate total impact on income and expenditure. The income and expenditure under shock conditions are compared against those in normal years (referred to as baseline years) and the gap between income and expenditure is combined with information on coping strategies by type of household livelihood group to identify food insecure households. The calculations are done typically in a spreadsheet.

In the second approach, which is more analytical, income‐expenditure elasticities are used to estimate changes in expenditure following a change in income arising from a production shock and/or a market shock and/or economic and policy shocks. One such model that is currently being tested in a number of countries is the WFP/FAO’s Shock Impact Simulation Model, SISModel, whose structure is shown graphically in Figure 5 (WFP and FAO 2013). As shown in Figure 5, the SISModel takes in as input shocks measured in terms of percentage change from baseline years for each of the three economic and climatic shocks. The model can be run at national level or at sub‐national level. The percentage change in crop production and/or livestock losses at either the national or sub‐ national level are the outputs of catastrophe crop/livestock models, however the market and economic and policy shocks, also, need to be separately provided by manually entering these to SISModel if their impacts are to be incorporated in the estimates of food security. Even if the input shocks were simplified to take into account production shortfalls resulting from a drought and food price hikes and changes in on‐farm labor demand, which would happen following a drought, it’s not clear how the associated price hikes and changes in labor demand would be specified unless simplified approaches like the one taken in EFSA are employed to use historical price hike data and historical reductions in labor demand following production shocks to estimate price hikes and labor demand changes that could be used as inputs to the SISModel. The subject area of market prices and labor and their role in food security is an ongoing research (WFP 2011). There are a number of market assessment methods (WFP 2013), and both the WFP and FAO regularly monitor agricultural commodity prices globally. Thus while there is a lot of work done on market prices with the FAO publishing _Global Food Price Monitor_<sup>_27_</sup> and the WFP publishing _The Market Monitor_<sup>_28_</sup> more work needs to be done to understand the dynamics of production shocks, food prices and labor demand so that these can be input in a food security vulnerability assessment model. In particular, there is a real need to understand the relationship between global food prices traded at major exchanges and local spot market prices to understand the impact on food accessibility at times of production shortfalls.

IFPRI has a model, the International Model for Policy Analysis of Agricultural Commodities and Trade, IMPACT, which carries out multi‐commodity, multi‐market analysis of demand, supply, and prices for 114 geopolitical regions of the world linked by international trade (Rosegrant et al. 2012). IMPACT even estimates the number of people at risk from hunger but it is based on the use of an adapted version of an empirical relationship between the share of malnourished within the total population and the relative availability of food (ibid.).

> 27 The FAO’s Global Food Price Monitor is available at http://www.fao.org/giews/english/gfpm/index.htm.

> 28 The WFP’s Market Monitor is available at http://www.wfp.org/content/market‐monitor.

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