gekslm_splice {PriceIndices}

Extending the multilateral GEKS-LM price index by using window splicing methods.

Description

This function returns a value (or values) of the multilateral GEKS-LM price index extended by using window splicing methods. Available splicing methods are: movement splice, window splice, half splice, mean splice and their additional variants: window splice on published indices (WISP), half splice on published indices (HASP) and mean splice on published indices (see References).

Usage

gekslm_splice(
  data,
  start,
  end,
  sigma = 0.7,
  window = 13,
  splice = "movement",
  interval = FALSE
)

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".

sigma

The elasticity of substitution (a parameter used in the Lloyd-Moulton index formula).

window

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

splice

A character string indicating the splicing method. Available options are: "movement", "window","half","mean", "window_published","half_published","mean_published".

interval

A logical value indicating whether the function is to provide the price index comparing the research period defined by end to the base period defined by start (then interval is set to FALSE) or all fixed base multilateral indices are to be presented (the fixed base month is defined by start).

Value

This function returns a value or values (depending on interval parameter) of the multilateral GEKS-LM price index extended by using window splicing methods. Available splicing methods are: movement splice, window splice, half splice, mean splice and their additional variants: window splice on published indices (WISP), half splice on published indices (HASP) and mean splice on published indices (see References). The time window starts in start and should consist of at least two months. 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

Chessa, A. G. (2019). A Comparison of Index Extension Methods for Multilateral Methods. Paper presented at the 16th Meeting of the Ottawa Group on Price Indices, 8-10 May 2019, Rio de Janeiro, Brazil.

de Haan, J., van der Grient, H.A. (2011). Eliminating chain drift in price indexes based on scanner data. Journal of Econometrics, 161, 36-46.

Krsinich, F. (2014). The FEWS Index: Fixed Effects with a Window Splice? Non-Revisable Quality-Adjusted Price Indices with No Characteristic Information. Paper presented at the UNECE-ILO Meeting of the Group of Experts on Consumer Price Indices, 2-4 May 2016, Geneva, Switzerland.

de Haan, J.(2015). A Framework for Large Scale Use of Scanner Data in the Dutch CPI. Paper presented at the 14th Ottawa Group meeting, Tokyo, Japan.

Diewert, W.E., and Fox, K.J. (2017). Substitution Bias in Multilateral Methods for CPI Construction using Scanner Data. Discussion paper 17-02, Vancouver School of Economics, The University of British Columbia, Vancouver, Canada.

Examples

gekslm_splice(milk, start="2018-12", end="2020-02", sigma=0.8, splice="half")