aiData function

Transforming Raw Data for Static AIDS Model

This function transforms import values and quantities into a data format that are needed for a static AIDS model. data

aiData(x, label, label.tot = "WD", prefix.value = "v",
  prefix.quant = "q", start = NULL, end = NULL, stone = TRUE, 
  dummy = NULL, season = c("none", "m", "q"), ...)

Arguments

• x: raw time series data such as daBedRaw.
• label: names of supplying countries; this can be as long as needed.
• label.tot: names of the world total (default label is "WD").
• prefix.value: prefix for value variables.
• prefix.quant: prefix for quantity varibles.
• start: start date for the transformed time series; this can be used to select a smaller window; the default is the start date of the raw data x.
• end: end date for the transformed time series.
• stone: whether the Stond Price Index is constructed (default TRUE); if FALSE, the version of log-linear analog to the Paasche index with lagged budget shares in Moschini (1995) is used. See references for detail.
• dummy: adding dummy variables if date ranges are provided as a list.
• season: adding seasonality variables or not; if yes, either monthly dummy or quarterly dummy; this is prepared mainly for monthly data.
• ...: additional arguments to be passed.

Details

This transforms raw import data into a format needed for a static AIDS model. This separation of data prepraration from model fitting allows greater flexibility in using aiStaFit in estimating a static AIDS model. In addition, when the raw data contain zero, a small number is substituted to avoid NA when the price variable (value/quantity) is calculated. The values for the residual supplier will change when the label is different.

Returns

Return a list object with two components: - out: a time series object ready for static AIDS models.

• share: a time series object of the share data.

• price: a time series object of the price data.

• quantity: a time series object of the quantity data.

• value: a time series object of the value data.

• m: a vector of the total expenditure.

• call: a record of the system call; this allows update.default to be used.

Methods

One method is defined as follows:

• print:: print the first several observations of the final data needed for the AIDS model.

References

Moschini, G. 1995. Units of measurement and the Stone index in demand system estimation. American Journal of Agricultural Economics 77(1):63-68.

Singh, K., M.M. Dey, and G. Thapa. 2011. An error corrected almost ideal demand system for crustaceans in the United States. Journal of International Food & Agribusiness Marketing 23(3):271-284.

Wan, Y., C. Sun, and D.L. Grebner. 2010. Analysis of import demand for wooden beds in the United States. Journal of Agricultural and Applied Economics 42(4):643-658.

Author(s)

Changyou Sun (edwinsun258@gmail.com )

See Also

aiStaFit; daBedRaw; daBed.

Examples

data(daBedRaw)
dumm <- list(dum1 = c(2003, 10, 2003, 10), dum2 = c(2004, 7, 2004, 7),
  dum3 = c(2005, 1, 2005, 1))
imp8 <- aiData(x = daBedRaw,
  label = c("CN", "VN", "ID", "MY", "CA", "BR", "IT"),
  label.tot = "WD", prefix.value = "v", prefix.quant = "q",
  start = c(2001, 1), end = c(2008, 12), dummy = dumm)
imp4 <- update(imp8, label = c("CN", "VN", "ID"))
imp5 <- update(imp4, label = c("CN", "VN", "ID", "MY"))
imp8; imp4; imp5
daTest <- imp8$out
colnames(daTest)[18:20] <- c("dum1", "dum2", "dum3")

data(daBed)
identical(daBed, daTest)