Calculated indices¶

Window: Add calculated index¶

• Name: Write the Name you want the Calculated Price Index to be identified.

• Base period start and end: The base period from when the ‘Base Value’ will be 100 (an average).

• Base value: Average from which calculations take place to easily see trend changes.

  • Will facilitate understanding of the value changes throughout time in percentages

  • This is relevant when a big change occurs and the data must be re-based (i.e. In countries with high inflation it rises to up to 400-500). It is relevant because when data was collected all the historic data was loaded and throughout the years price changes are big and so it must be re-based to make sense of the data in an easy way.

    • Such re-base average (100) will be between the base period start and the base period end.

    • Bear in mind the start and end dates of the base period are obligatory, otherwise the system will not work.

• Currency: When you select the currency, the system will automatically convert the individual price series from any currency to the currency that is selected.

  • If the Price index value is calculated from data series with secondary rates ensure that you have entered the exchange rate to the currency in which you want the calculation to be made.

  • I.e. SOS: One of Somalia’s currencies which is not part of the international financial system will always be a secondary rate and therefore if one of the Price Series is in SOS and your selected currency is USD, you will then ensure the exchange rate for SOS-USD exists in the system for the period dates you would like such calculation to be made.

  • Exchange rates must be entered from Price under Dataseries Management.

• Weighted? To create an Unweighted Price Index, please do not select this option.

  • Unweighted: When only selecting the price index components

  • Weighted: When after selecting the price index components you add a weight to each of them

• Start and End dates: Optional. By default it will select all the available data within the selected time data series

• Description: Optionally you can explain the purpose of the Calculated index you are creating.

• Visibility / Owner: If you have been contacted to make a specific Calculated index available, it is from here that you can give access to others

• Calculated index components: To create an Unweighted Price Index, please select the Data Series you will need but do not add the weights.

  • Data Series: Select the data series you will need.

  • Weighting: Include the weighting values

  • Add another Calculated Index Component: You may add as many components as you like. If weighting, you must ensure the weightings add up to 1.

Weighting Example: [X+Y+Z = 1]

• *       * Nairobi Sales ÷ [Sales in Nairobi + Kampala + Arusha] = X
  

  • Kampala Sales ÷ [Sales in Nairobi + Kampala + Arusha] = Y

  • Arusha Sales ÷ [Sales in Nairobi + Kampala + Arusha] = Z

An unweighted price index is a calculated index created by FDW-P

• *       * At the moment there are some calculated indexes on an excel workbook that both F.O. and H.O. use (unweighted)
  

  • These are a straight average: i.e. East African Maize Prices based on three components (Nairobi, Kampala, Arusha): the cost of each converted into USD/ per Kg added and then divided by 3.

  • This is not the ideal way of doing it because it is not proportionate to the population size of each component.

  • But it is done as such because excel does not have the capacity in terms of the difficulty in maintaining the formulate in excel.

  • In reality when creating an index, it should almost always be weighted

Note: To add a calculated index to a Data Set, please access the calculated index from Single data series and follow the instructions from there.