The classification between AD, MCI at its two levels (EMCI and LMCI), and NC using PET imaging is a topic that has been studied by previous groups.
Due to the subtle differences in imaging, EMCI and LMCI are a particularly challenging problem for classification, especially using amyloid imaging such as PET.
A final set of 660 subjects with PET and MRI images as well as MMSE scores at both timepoints was selected, which amounted to 99 AD, 164 EMCI, 189 LMCI, and 208 NC.
The results of four paired classes (AD versus NC, AD versus EMCI, AD versus LMCI, and EMCI versus LMCI) of cognitive states are presented in Tables 3 and 4.
On the other hand, the RF classifier for the whole-brain approach demonstrated the highest accuracies for AD versus LMCI and EMCI versus LMCI (81.7% and 72.5%, resp.) compared to the other classifiers which were between 55% and 68.2%.
These results demonstrate the high accuracy of RBF-SVM and RF classifiers for AD versus NC (90.8% versus 87.9%), AD versus EMCI (80.0% versus 88.0%), and AD versus LMCI (88.9% versus 81.5%).
Two simple policy rules are estimated in which the real federal funds rate depends on the deviation of inflation from its desired level (assumed to be 2 percent) and either the unemployment rate gap or the two labor market indicators from the LMCI:
where [ffr.sub.t] is the federal funds rate in period t, r is the constant term, [p.sub.t] is the inflation rate as measured by the core personal consumption expenditure (PCE) price index over 12 months, [ugap.sub.t] is the Congressional Budget Office (CBO) measure of the unemployment gap, and [Level.sub.t] and Momentumt come from the LMCI. (8) The coefficient [rho] measures the degree of policy inertia--the dependence of the current federal funds rate on its level from the previous month.
Notably, though, the rule with the LMCI came considerably closer to the actual path than the rule with the unemployment gap, especially from September 2007 to December 2008 as the FOMC lowered the federal funds rate target from 5U percent to its effective lower bound.
According to the rule with the LMCI, the funds rate prescription fell quickly, reaching a low of minus 3.5 percent in November 2009.
The funds rate prescriptions start rising in late 2009 for the rule with the LMCI and in late 2010 for the rule with the unemployment gap.