Table 3.
Linear equations for age, body length, and body weight prediction derived from stepwise linear regression analysis.
| Model | Function | Adj. R2 | P-value | RSE |
|---|---|---|---|---|
| Age prediction | ||||
| Combined (male + female) | ||||
| Parameter# | Y = 2.55(A) + 0.46(ISL) − 46 | 0.35 | 0.002 | 13.94 |
| Index | Y = 45.474 + 30.99(A/P) − 44.1(IL/ISL) | 0.39 | 0.001 | 13.59 |
| Mixed# | Y = 2.55(A) + 0.46(ISL) − 46 | 0.35 | 0.002 | 13.94 |
| Male | ||||
| Parameter | Y = 0.3(PL) + 0.27(P) − 38.36 | 0.97 | 0.000 | 1.04 |
| Index | Y = 22.17 + 20.31(A/P) − 22.36(IL/ISL) | 0.30 | 0.118 | 5.26 |
| Mixed | Y = 41.35(PL/IL) + 2.26(BL/PL) + 0.72(IL) − 160.9 | 0.99 | 0.000 | 0.65 |
| Female | ||||
| Parameter* | Y = 0.82(ISL) − 22.46 | 0.44 | 0.003 | 12.36 |
| Index | Y = 86.46 − 42.27(ISL/IL) | 0.39 | 0.005 | 12.93 |
| Mixed* | Y = 0.82(ISL) − 22.46 | 0.44 | 0.003 | 12.36 |
| Body length prediction | ||||
| Combined (male + female) | ||||
| Parameter | Y = 682.9 + 11.32(PL) | 0.84 | 0.000 | 190.8 |
| Index | Y = 1892.95(PL/IL) + 977.18(PL/ISL) + 546.98(A/P) − 79.51(BL/PL) − 2686.46 | 0.36 | 0.000 | 373.6 |
| Mixed | Y = 19.17(IL) + 12.19(ISL) + 69.3(BL/PL) − 1104.89 | 0.93 | 0.000 | 127.5 |
| Male | ||||
| Parameter | Y = 493.95 + 8.09(IL) + 77.2(ARW) | 0.87 | 0.000 | 151.2 |
| Index | Y = 1804.64 + 674.96(PL/IL) − 59.1(BL/PL) | 0.19 | 0.003 | 370.32 |
| Mixed | Y = 16.94(IL) + 12.51(ISL) + 9.89(P) + 83.87(BL/PL) − 10.21(A) − 1260.51 | 0.97 | 0.000 | 68.8 |
| Female | ||||
| Parameter | Y = 598.92 + 12.42(PL) | 0.87 | 0.000 | 191.3 |
| Index | Y = 4143.68(PL/IL) + 2723.85(PL/ISL) + 436.14(A/P) − 117.53(BL/PL) − 9905.01 | 0.58 | 0.000 | 360.9 |
| Mixed | Y = 15.75(PL) + 55.4(ARW) + 67.24(BL/PL) − 42.27(NW) − 1416.43 | 0.95 | 0.000 | 120.7 |
| Body weight prediction | ||||
| Combined (male + female) | ||||
| Parameter | Y = 2043.3(PL) − 79,613.2 | 0.76 | 0.000 | 42,870 |
| Index | Y = 468,868(PL/IL) + 267,864(PL/ISL) + 80,557(A/P) − 14,131(BL/PL) − 1,115,231 | 0.34 | 0.012 | 71,060 |
| Mixed | Y = 2876.7(PL) + 12,941.3(BL/PL) − 410,792.4 | 0.85 | 0.000 | 33,870 |
| Male | ||||
| Parameter | Y = 2068.2(PL) − 92,844.5 | 0.85 | 0.000 | 28,240 |
| Index | Y = 50,078 + 167,176(PL/IL) − 12,024(BL/PL) | 0.29 | 0.000 | 62,480 |
| Mixed | Y = 2482.4(PL) + 1760.2(P) + 11,366.7(BL/PL) − 366,168.7 | 0.94 | 0.000 | 17,680 |
| Female | ||||
| Parameter | Y = 2043.2(PL) − 68,462.5 | 0.72 | 0.000 | 53,290 |
| Index | Y = 833,125(PL/IL) + 608,648(PL/ISL) −22,079(BL/PL) − 2,303,445 | 0.39 | 0.000 | 78,340 |
| Mixed | Y = 3845.4(IL) + 2155.6(ISL) + 14,191.7(BL/PL) − 452,235 | 0.79 | 0.000 | 45,250 |
Y predictor; age (years), body length (mm) or body weight (g), Adj.R2 adjusted R-square, RMSE root mean square error, Parameter using raw value of each parameter in calculation, Index = using Index value in calculation, Mixed using parameter and index value in calculation.
Same symbol (*, #) had a similar, function, adjust R2, P-value and RSE.