elasticity_fig {PriceIndices}

Presenting elasticities of substitution for time interval

Description

The function provides a data frame or a figure presenting elasticities of substitution calculated for time interval.

Usage

elasticity_fig(
  data,
  start,
  end,
  method = c("lm"),
  fixedbase = TRUE,
  figure = TRUE,
  date_breaks = "1 month",
  names = c(),
  left = -10,
  right = 10,
  precision = 1e-06
)

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".

method

A vector indicating index formulas for which the CES index will be equated to calculate the elasticity. Acceptable options are lm, f, t, w and sv or their combinations.

fixedbase

A logical parameter indicating whether the procedure is to work for subsequent months from the considered time interval (fixedbase=FALSE). Otherwise the period defined by start plays a role of fixed base month (fixedbase=TRUE)

figure

A logical parameter indicating whether the function returns a figure (TRUE) or a data frame (FALSE) with values of elasticity of substitution.

date_breaks

A string giving the distance between breaks on the X axis like "1 month" (default value) or "4 months".

names

A character string indicating names of indices used for elasticity approximation (see the method parameter).

left

The beginning of an interval for estimation of each elasticity of substitution (its default value is -10)

right

The end of an interval for estimation of each elasticity of substitution (its default value is 10)

precision

The precision of estimation (a 'stop' condition for the procedure). A default value of this parameter is 0.000001.

Value

The function provides a data frame or a figure presenting elasticities of substitution calculated for time interval (see the figure parameter). The elasticities of substitution can be calculated for subsequent months or for a fixed base month (see the start parameter) and rest of months from the given time interval (it depends on the fixedbase parameter). The above-mentioned parameters for compared months are calculated by using the elasticity function.

References

de Haan, J., Balk, B.M., Hansen, C.B. (2010). Retrospective Approximations of Superlative Price Indexes for Years Where Expenditure Data Is Unavailable. In: Biggeri, L., Ferrari, G. (eds) Price Indexes in Time and Space. Contributions to Statistics. Physica-Verlag HD.

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

Examples

elasticity_fig (milk,start="2018-12",end="2019-04",figure=TRUE, 
method=c("lm","f"),names=c("LM","Fisher"))
elasticity_fig (milk,start="2018-12",end="2019-06",figure=FALSE)