Which publication type for forthcoming papers in BibTeX?
For forthcoming articles of the sort that you give in your question, the easiest solution is to simply format them as article type, and then put "to appear" in the pages field. A forthcoming article won't have a page range yet, and when the article is published you will have to add the page range anyway. In the econ bibliography style, (and in fact most bibliography styles for article) the page range appears last in the entry, so it will be formatted as you wish.
Alternatively, (as pointed out in the comments) you can add the "to appear" as a note field. To do this in BibDesk, you need to do the following:
- Open the entry for the article
- In the Publication menu, choose Add Field
- In the pulldown textbox, choose Note
This solution is semantically good, but in practice it may not be as robust as putting the "to appear" in the pages field, since the appearance of the field depends on the particular bibliography style you are using; if the style isn't set up to output the note field, then the problem will reappear.
(Another common way to do this is to not give a year, and replace the year field with "to appear". This will, of course, replace it in both bibliography and citations.)
For chapters in books, the incollection entry type should be used. The inbook entry (which may have been what you were using) is really designed for referring to a particular chapter of a single-authored or edited book; you're not likely to use it much at all, since most citations of that sort can be done using the book entry and adding the chapter reference to the citation command.
Biblatex (not BibTeX) defines a field pubstate, where you can set different types like inpress, submitted, forthcoming, etc. The full list is in the biblatex manual.
Use the field "intype":
intype = {to appear in},
Note: this works with (at least) IEEEtranS.bst