This function returns a value of the multilateral GEKS-IQM price index extended by using the FBMW (Fixed Base Moving Window) method.
geksiqm_fbmw(data, start, end, r)This function returns a value of the multilateral GEKS-IQM 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).
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).
The base period (as character) limited to the year and month, e.g. "2019-12".
The research period (as character) limited to the year and month, e.g. "2020-04".
The real and non-zero parameter used in the implicit quadratic mean of order r price index.
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.
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.
geksiqm_fbmw(milk, start="2019-12", end="2020-04", r=1.6)
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