Plotting first differences with ci.plot() does not work

[Gregor Kvas]

What is the correct value for the parameter 'qi' in the plot function 'ci.plot()' to plot first differences? The value "fd" does not work in 'ci.plot(obj, qi = "fd", ...)' and leads to the error message:

Error: Can't find column fd in .data.

Thx for any help!
Greetings, Gregor

[James Honaker]

In general, I believe fd is correct as the argument, but you have to have a Zelig object that contains first differences. Which is to say you'll need to have done both a setx() and setx1() call. See:
http://docs.zeligproject.org/articles/quickstart.html#building-models

However, there is supposed to be a softer error message that lists out the all the available quantities of interest in the Zelig object, if you ask for one that isn't present. So the message that you quote suggests there might be a deeper issue in the model you ran, in the Zelig code somewhere.