Analisis estimasi cadangan klaim IBNR (incurred but not reported) untuk produk asuransi kesehatan dengan metode klasik chain-ladder dan bornhuetter-ferguson (studi kasus pada PT. Ssuransi GHI) = Analysis estimated IBNR claims reserves (incurred but not reported) for health insurance product with classic chain ladder method and bornhuetter ferguson method (case study at PT. Asuransi GHI) / Erick Hizkia Pangihutan Marbun