13.6 The table gives the data used by Cobb and Douglas (1928) to fit the original Cobb-Douglas production function:

Yt, Kt, and Lt, being index number series for real output, real capital input, and real labor input, respectively, for the manufacturing sector of the United States for the period 1899–1922 (1967=100). The model was linearized by taking logarithms of both sides and the following regressions were run (standard errors in parentheses; method of estimation as indicated):

Evaluate the three regression specifications.

Year Y K L Year Y K 7 1899 100 100 100 1911 153 216 145 1900 101 107 105 1912 177 226 152 1901 112 114 110 1913 184 236 154 1902 122 122 118 1914 169 244 149 1903 124 131 123 1915 189 266 154 1904 122 138 116 1916 225 298 182 1905 143 149 125 1917 227 335 196 1906 152 163 133 1918 223 366 200 1907 151 176 138 1919 218 387 193 1908 126 185 121 1920 231 407 193 1909 155 198 140 1921 179 417 147 1910 159 208 144 1922 240 431 161 Source: Cobb and Douglas (1928)