geksiqm {PriceIndices}

Calculating the multilateral GEKS-IQM price index

Description

This function returns a value of the multilateral GEKS-IQM price index (to be more precise: the GEKS index based on the implicit quadratic mean of order r price index IQMp).

Usage

geksiqm(data, start, end, r = 2, wstart = start, window = 13)

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. "2020-03".

end

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

r

The real and non-zero parameter used in the implicit quadratic mean of order r price index.

wstart

The beginning of the time interval (which is used by multilateral methods) limited to the year and month, e.g. "2020-01".

window

The length of the time window (as positive integer: typically multilateral methods are based on the 13-month time window).

Value

This function returns a value of the multilateral GEKS-IQM price index (to be more precise: the GEKS index based on the the implicit quadratic mean of order r price index IQMp) which considers the time window defined by wstart and window parameters. It measures the price dynamics by comparing period end to period start (both start and end must be inside the considered time window). 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

Gini, C. (1931). On the Circular Test of Index Numbers. Metron 9:9, 3-24.

Elteto, O., and Koves, P. (1964). On a Problem of Index Number Computation Relating to International Comparisons. Statisztikai Szemle 42, 507-518.

Szulc, B. (1983). Linking Price Index Numbers. In: Price Level Measurement, W. E. Diewert and C. Montmarquette (eds.), 537-566.

(2004). Consumer Price Index Manual. Theory and practice. ILO/IMF/OECD/UNECE/Eurostat/The World Bank, International Labour Office (ILO), Geneva.

Examples

geksiqm(milk, start="2019-01", end="2019-08",window=10)
geksiqm(milk, start="2018-12", end="2019-12", r=1.6)