Jackman (Chapter 6) additionally focuses on measurement, starting from the basic test concept mannequin in which an indicator is the same as a latent variable plus some error. He reminds us that good measures should be each valid and reliable, and defines these standards fastidiously.
One is the complicated however tractable issue of autocorrelation, which usually implies that time series have much less data in them per remark than cross‐sectional data and which recommend that some variables have been omitted from the specification (Beck and Katz 1996; Beck 2003). The second is the more pernicious downside of unit roots and generally trending (co‐integrated) knowledge which can result in nonsense correlations. In impact, in time‐sequence data, time is almost all the time an “omitted” variable that may result in spurious relationships which cannot be simply (or sensibly) disentangled by merely adding time to the regression. The most impressive accomplishment of this … Read More