Files with a .csv extension are comma-separated text with
variable names included. They may be read into Stata with insheet using filenameinto R with df <-
read.csv(filename) and
into SPSS or SAS with the text data import wizards in those packages.
Files with a .txt extension are free-format text. Variable
names are supplied only in the documentation file.
Files with a .dta extension are Stata binary files.