RDP 9601: Why Does the Australian Dollar Move so Closely with the Terms of Trade? Equation (2)

η ^ = t=1 T S t 2 T 2 s 2 ( k ) MathType@MTEF@5@5@+=feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGafq4TdGMbaKaacqGH9aqpdaWcaaqaamaaqahabaGaam4uamaaDaaaleaacaWG0baabaGaaGOmaaaaaeaacaWG0bGaeyypa0JaaGymaaqaaiaadsfaa0GaeyyeIuoaaOqaaiaadsfadaahaaWcbeqaaiaaikdaaaGccaWGZbWaaWbaaSqabeaacaaIYaaaaOWaaeWaaeaacaWGRbaacaGLOaGaayzkaaaaaaaa@4784@