tpd_fbmw {PriceIndices}

Extending the multilateral TPD price index by using the FBMW method.

Description

This function returns a value of the multilateral TPD price index (Time Product Dummy index) extended by using the FBMW (Fixed Base Moving Window) method.

Usage

tpd_fbmw(data, start, end)

Arguments

data

The user's data frame with information about sold products. It must contain columns: time (as Date in format: year-month-day,e.g. '2020-12-01'), prices (as positive numeric), quantities (as positive numeric) and prodID (as numeric, factor or character).

start

The base period (as character) limited to the year and month, e.g. "2019-12".

end

The research period (as character) limited to the year and month, e.g. "2020-04".

Value

This function returns a value of the multilateral TPD price index extended by using the FBMW (Fixed Base Moving Window) method. It measures the price dynamics between periods end and start and it uses a 13-month time window with a fixed base month taken as year(end)-1. If the distance between end and start exceeds 13 months, then internal Decembers play a role of chain-linking months. The month of the start parameter must be December. To get information about both price index values and corresponding dates, please see functions: price_indices or final_index. The function does not take into account aggregating over outlets or product subgroups (to consider these types of aggregating, please use the final_index function).

References

de Haan, J. and F. Krsinich (2014). Time Dummy Hedonic and Quality-Adjusted Unit Value Indexes: Do They Really Differ? Paper presented at the Society for Economic Measurement Conference, 18-20 August 2014, Chicago, U.S.

Lamboray, C.(2017). The Geary Khamis index and the Lehr index: how much do they differ? Paper presented at the 15th Ottawa Group meeting, 10-12 May 2017, Elville am Rhein, Germany.

Examples

tpd_fbmw(milk, start="2019-12", end="2020-04")