the two types of indexes during periods of seasonal price hikes is about 2-4 index points for Pakistan and Afghanistan, and is smaller for India. Second, for Pakistan and to some degree for India, the gap between NPI and the food CPI is increasing across years.

We further look into which specific food groups are driving the seasonality gap and the increasing overall gap between NPI and the food CPI for certain countries (see Appendix Figure A1). For countries where a gap between NPI and the food CPI exists, we find that the trends in vegetable and legume prices are driving the gap.

Interestingly, in Sri Lanka vegetable prices have fallen (in 2013 and 2014) relative to the base year, while prices for dairy and eggs have not been rising at a rapid rate. These trends seem to be muting the difference between NPI and the food CPI in Sri Lanka. In Pakistan, the overall food CPI increase is mostly driven by rising prices for meat products, fruits, vegetables, sugar, and other food products. The seasonality is mostly driven by the price of vegetables and fruits. Unsurprisingly, much of the differences between NPI and the food CPI are due to the price of vegetables (and fruits).

In Afghanistan, as in Pakistan, the price of oils and fat are the most stable and unchanged, but unlike in Pakistan, cereal prices in Afghanistan have gradually increased. Cereals are more heavily weighted in the food CPI than in the NPI, so theoretically, the cereal price increase should lead to a faster increasing food CPI than NPI. However, the increase in other food groups that are more heavily weighted in the NPI (such as fruits) cancels out the overall gap between food CPI and NPI. What we do observe in Afghanistan is a seasonal gap between food CPI and NPI. Thus, vegetables seem to be driving the difference between NPI and the food CPI, since the price of vegetables is seasonal but has not increased over time.<sup>26</sup> In India, prices have increased the fastest for vegetables, fruits, seafood, and meat products, and slowest for beverages, sugar, and oils and fats. Not only have vegetable and pulse prices been increasing the fastest, these prices have also been the most seasonal. Thus, the more subdued gap between NPI and food CPI in India is not so much due to a weak link between vegetable prices and seasonality, but rather due to the smaller difference in the nutritional and expenditure weights for vegetables and pulses in India, relative to those for Pakistan and Afghanistan.

# **5 Extension to CoRD: Using household survey data in Sri Lanka and Pakistan**

This main proof of concept in this paper is to demonstrate that data from existing price monitoring systems can easily be used to measure and understand the cost of nutritious food across time and geographic locations. In calculating CoRD we had used food prices collected by the NSO in selected markets (cities) to calculate the CPI. The main concern, however, is that these prices might not be a good representation of the actual prices experienced by certain consumers, especially those living in remote rural areas. An alternative to CPI data would be to use food prices from household surveys (deduced from the unit values in a consumption module). Household surveys are less ideal for real time price monitoring as they are administered less frequently (for example, every five years, as opposed to monthly for the CPI). But they are nationally representative as well as representative at some subnational level.

> 26 We also caution that the Afghanistan results are not directly comparable to the Pakistan and India results, because, due to data limitations, the Afghanistan NPI is a hybrid between the NPI and the food CPI.

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