dissimilarity: Calculating the relative price and/or quantity dissimilarity measure between periods
Description
This function returns a value of the relative price and/or quantity dissimilarity measure.
Usage
dissimilarity(data, period1, period2, type = "p")
Value
This function returns a value of the relative price (dSP) and/or quantity (dSQ) dissimilarity measure. In a special case, when the type parameter is set to pq, the function provides the value of dSPQ measure (the relative price and quantity dissimilarity measure calculated as min(dSP,dSQ).
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).
period1
The first period (as character) limited to the year and month, e.g. '2019-03'.
period2
The second period (as character) limited to the year and month, e.g. '2019-04'.
type
The parameter indicates what type of dissimilarity measure is to be calculated. Possible values of the type parameter are: p (for the price dissimilarity measure calculation), q (for the quantity dissimilarity measure calculation) or pq (for the dSPQ measure calculation, i.e. the measure of relative price and quantity dissimilarity - see References).
References
Diewert, E. (2020). The Chain Drift Problem and Multilateral Indexes. Chapter 6 in: Consumer Price Index Theory (draft)