[ABSTRAK
Integrasi vertikal dapat dijadikan salah satu strategi untuk meningkatkan daya saing Indonesia yang saat ini berada dalam posisi rendah. Untuk dapat menjalankan strategi integrasi vertikal perlu diketahui faktor-faktor yang mempengaruhinya. Menurut Stigler (1984) terdapat 3 (tiga) hipotesis yang berhubungan dengan integrasi vertikal yaitu rasio konsentrasi 4 perusahaan terbesar (CR4) dan pertumbuhan permintaan (growth) berpengaruh positif, sedangkan ukuran rata-rata perusahaan berpengaruh (avsize) negatif terhadap tingkat integrasi vertikal. Penelitian ini melibatkan 5 industri dari beragam sektor yakni industri kendaraan bermotor roda empat, industri pengolahan tembakau, industri pengolahan minyak goreng sawit, industri kertas, dan industri tekstil serta produknya untuk periode 2001-2011. Hasil penelitian menunjukkan bahwa CR4 industri pengolahan minyak goreng sawit dan industri kertas berpengaruh signifikan, pertumbuhan permintaan pada semua industri tidak berpengaruh signifikan, dan Avsize pada industri kertas dan tekstil dan produk tekstil berpengaruh signifikan terhadap tingkat integrasi vertikal dan sesuai dengan hipotesis Stigler.

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ABSTRACT
Vertical integration may be one of strategy to improve the competitivenes Indonesia which is currently in a low position. Before we implement the strategy, we need to know the factors that related on it. According to Stigler (1984), there are three (3) hypothesis associated with vertical integration: the concentration ratio of 4 biggest companies (CR4) and the growth of demand (growth) has positive effect, while the average of firm size (avsize) has negative affect to the level of vertical integration. This research wants to verify the hypothesis using panel data on five industries namely four-wheeled motor vehicle industry, the tobacco processing industry, palm oil processing industry, paper industry, and textile industry in the period from 2001 to 2011. The result showed that CR4 cooking palm oil processing industry and paper industries have a positive and significant effect. Meanwhile the growth of all industries haven't significant effect, and Avsize on paper and textile industries have a negative and significant effect on the level of vertical integration.;Vertical integration may be one of strategy to improve the competitivenes Indonesia which is currently in a low position. Before we implement the strategy, we need to know the factors that related on it. According to Stigler (1984), there are three (3) hypothesis associated with vertical integration: the concentration ratio of 4 biggest companies (CR4) and the growth of demand (growth) has positive effect, while the average of firm size (avsize) has negative affect to the level of vertical integration. This research wants to verify the hypothesis using panel data on five industries namely four-wheeled motor vehicle industry, the tobacco processing industry, palm oil processing industry, paper industry, and textile industry in the period from 2001 to 2011. The result showed that CR4 cooking palm oil processing industry and paper industries have a positive and significant effect. Meanwhile the growth of all industries haven't significant effect, and Avsize on paper and textile industries have a negative and significant effect on the level of vertical integration., Vertical integration may be one of strategy to improve the competitivenes Indonesia which is currently in a low position. Before we implement the strategy, we need to know the factors that related on it. According to Stigler (1984), there are three (3) hypothesis associated with vertical integration: the concentration ratio of 4 biggest companies (CR4) and the growth of demand (growth) has positive effect, while the average of firm size (avsize) has negative affect to the level of vertical integration. This research wants to verify the hypothesis using panel data on five industries namely four-wheeled motor vehicle industry, the tobacco processing industry, palm oil processing industry, paper industry, and textile industry in the period from 2001 to 2011. The result showed that CR4 cooking palm oil processing industry and paper industries have a positive and significant effect. Meanwhile the growth of all industries haven't significant effect, and Avsize on paper and textile industries have a negative and significant effect on the level of vertical integration.]