walsh.cottonprice.Rd
Acres and price of cotton 1910-1943
A data frame with 34 observations on the following 9 variables.
year
year, numeric 1910-1943
acres
acres of cototn (1000s)
cotton
price per pound (cents) in previous year
cottonseed
price per ton (dollars) in previous year
combined
cotton price/pound + 1.857 x cottonseed price/pound (cents)
index
price index, 1911-1914=100
adjcotton
adjusted cotton price per pound (cents) in previous year
adjcottonseed
adjusted cottonseed price per ton (dollars) in previous year
adjcombined
adjusted combined price/pound (cents)
The 'index' is a price index for all farm commodities.
R.M. Walsh (1944). Response to Price in Production of Cotton and Cottonseed, Journal of Farm Economics, 26, 359-372. https://doi.org/10.2307/1232237
library(agridat) data(walsh.cottonprice) dat <- walsh.cottonprice dat <- transform(dat, acres=acres/1000) # convert to million acres percentchg <- function(x){ # percent change from previous to current ix <- 2:(nrow(dat)) c(NA, (x[ix]-x[ix-1])/x[ix-1]) } # Compare percent change in acres with percent change in previous price # using constant dollars dat <- transform(dat, chga = percentchg(acres), chgp = percentchg(adjcombined)) with(dat, cor(chga, chgp, use='pair')) # .501 correlation#> [1] 0.5008616