Re: [Gretl-users] creating ID variables

Data Analytics Corp. schrieb: > Hi, > > Suppose I have a data set of 200 cars where the observation labels are > the make (Chevy, Honda, BMW, etc.). Say there are 10 makes. I want to > create a variable, say ID, that identifies the make so I don't have to > rely on the observation label. The purpose is to later create dummies > for the makes to include in a regression model and create boxplots (one > for each make's price, all shown in one plot window) of price. How can > I do this? Or is it better to just use the observation labels and > laboriously write if statements? > > AFAIK the term "observation labels" in gretl terminology is used to describe individual datapoints, not as a field to hold certain defining characteristics which is effectively a variable. So, starting from a spreadsheet file, if you put the "make" variable in its own column (with character string values) then gretl should automatically code it with numerical values and notify you when you import that file (in .csv form). Then it seems to me that you will have what you need: You can restrict the sample to those obs where the ID equals a certain number code. If you want you can also create dummies like so: series hondadummy = (ID=5) # example with code 5 for Honda This can also be done for all makes in one step in the GUI I think: try Add -> create dummies for selected discrete variables. HTH, sven