utpd_fbmw {PriceIndices}

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

Description

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

Usage

utpd_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 unweighted 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

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