matlab多项式拟合的一个疑问。

f(x) = p1*x^2 + p2*x + p3

Coefficients (with 95% confidence bounds):

p1 = 1.72 (0.9384, 2.503)

p2 = 54.63 (20.93, 88.33)

p3 = -331 (-621.1, -40.95)

Goodness of fit:

SSE: 6.069e+004

R-square: 0.9962

Adjusted R-square: 0.9951

RMSE: 93.12

这是我拟合后的结果，曲线显示拟合很好，为什么SSE和RMSE很大呢，不是越小越好吗，哪里出了问题，求高人啊