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Table 2 Panel unit root test results for R&D share, number of patents and PCGDP growth rate

From: Interplays among R&D spending, patent and income growth: new empirical evidence from the panel of countries and groups

Method Null hypothesis Test statistics with intercept (prob.) Test statistics with intercept & trend (prob.)
   R&D Patent PCGDPGrth R&D Patent PCGDPGrth
Levin, Lin and Chu Unit root (under common unit root process) − 4.845 (0.00) − 4.235 (0.00) − 14.94 (0.00) − 4.433 (0.00) − 4.40 (0.00) − 13.82 (0.00)
Bruitang t test Unit root (under common unit root process) - - - − 4.35 (0.00) − 4.58 (0.00) − 10.92 (0.00)
Im, Pesaran and Shin Unit root (under individual unit root process) − 4.81 (0.00) − 4.279 (0.00) − 13.50 (0.00) − 3.811 (0.00) − 3.90 (0.00) − 12.35 (0.00)
MW-ADF–Fisher chi-square Unit root (under individual unit root process) 74.39 (0.00) 70.256 (0.00) 198.92 (0.00) 60.245 (0.00) 62.31 (0.00) 164.24 (0.00)
MW-PP– Fisher chi-square Unit root (under individual unit root process) 150.02 (0.00) 105.80 (0.00) 1051.12 (0.00) 158.86 (0.00) 95.97 (0.00) 965.24 (0.00)
  1. Note: Automatic lag length selection is based on AIC: 1 to 4. Probabilities for Fisher tests (source: computed by the authors using Eviews)