Georgios Chortareas and George Kapetanios, "How Puzzling is the PPP Puzzle? An Alternative Half-Life Measure of Convergence to PPP", Journal of Applied Econometrics, Vol. 28, No. 3, 2013, pp. 435-457. The file ck-data.xls contains US real exchange rate data for France, Germany, Italy, Japan, Spain and the UK in each of the six columns respectively for 1957Q1-1998Q4 (168 observations). This file is zipped in ck-xls.zip. The file ck-data.csv contains the same data in comma-separated format. It is zipped in ck-csv.zip. Since ck-data.csv is an ASCII file in DOS format, Unix/Linux users should use "unzip -a".