The State Planing Organization Research Fund,
under Project no. 05-DPT-03/008. This
manuscript comprises a part of Emine Şen’s
doctoral dissertation. We thank Zekiye Karaçam
and Nilay Bümen (Education Faculty of Ege
University) for her guidance in study, Hatice
Uluer and Mehmet Orman
forstatisticalconsultation.