Methodology
Retail prices are taken from two sources, the Central Bank of Sri Lanka (CBSL) and a local supermarket.
The retail price data from the CBSL is taken from the “Weekly Economic Indicators” published by the Statistics department of the Central Bank of Sri Lanka. The retail prices used are from the Pettah Market, except where data is unavailable, in which case data from the Narahenpita Economic Centre is used.
Additionally, supermarket retail price data is calculated using the formula = Total Sales/Total Volume.
The items selected for the BCI are selected from the HIES 2016 survey. The table of “Food items consumption and expenditure (average monthly per household) – Sri Lanka – 2016”, was used to approximate the quantities.
The quantities of the each of the goods in the basket are given below:
| Samba Rice | 1250g |
| Beans | 250g |
| Pumpkin | 250g |
| Tomatoes | 100g |
| Brinjals | 1000g |
| Dhal (Indian) | 500g |
| Red Onion | 200g |
| Coconut | 6 |
| Green Chilli | 100g |
| Fish * | 250g |
The goods chosen for the BCI basket are the commonly consumed food groups as per the HIES survey, but the specific items selected are based on the availability of price data from the CBSL.
For example in the HIES Survey, for fish, canned fish (salmon) have higher consumption quantities than balaya. However they are not reported in “Weekly Economic Indicators”. Therefore balaya is being used as a proxy for the group.
The price data are updated weekly as the CBSL publishes the “Weekly Economic Indicators”. The arithmetic mean of the weekly prices are then uploaded monthly to the website.
We thank economist Deshal de Mel who’s personal project The Buth Curry Index provided the inspiration for this project.