Dear experts, ? ?i want to use nlme or plm to?analysis mixed effect model, my data has the format : ? city ?year ?area ? ?y ? x ?? ? ?1 ? ?2010 ? A ? ? 1.2 ? 2 ? ?1 ? ?2011 ? A ? ? 3 ? ?3 ? ? 2 ? 2010 ? A ? ? 5 ? ?4 ? ? 2 ? 2011 ? A ? ?2.1 ? 1.8? ? 3 ?2010 ?B ? ? ?1.7 ? ?2 ? ? ? ........ I want to know does y has relationsheep with x? how to use nlme or plm to do the ?task? ?the two packages seems does not have viggnette to guide me ? Does anyone happen to know ? -- PO SU mail: desolator88 at 163.com Majored in Statistics from SJTU