一个有效的工具变量应满足如下两个条件
A: corr(Zi, Xi) = 0 and corr(Zi, ui) ≠ 0
B: corr(Zi, Xi) = 0 and corr(Zi, ui) = 0.
C: corr(Zi, Xi) ≠ 0 and corr(Zi, ui) = 0
D: corr(Zi, Xi) ≠ 0 and corr(Zi, ui) ≠ 0
A: corr(Zi, Xi) = 0 and corr(Zi, ui) ≠ 0
B: corr(Zi, Xi) = 0 and corr(Zi, ui) = 0.
C: corr(Zi, Xi) ≠ 0 and corr(Zi, ui) = 0
D: corr(Zi, Xi) ≠ 0 and corr(Zi, ui) ≠ 0
举一反三
- 已知某线性相位FIR滤波器的零点Zi,则下面哪些点仍是该滤波器的零点 A: Zi* B: 1/Zi* C: 1/Zi D: 0
- 改进dh参数di参数含义为以下哪个选项？ A: 沿着Zi轴，从Xi-1移动到Xi的距离 B: 沿着Xi-1轴，从Zi-1旋转到Zi的距离 C: 绕着Zi轴，从Xi-1旋转到Xi的角度 D: 绕着Xi-1轴，从Zi-1移动到Zi的角度
- Su Dongpo compared the West Lake to Xi Zi, one of the four beauties in ancient China.
- 设随机变量(X,Y)服从均匀分布U(D), 其中D={(x,y): 0<x-y<0.5, 0<x<1, 0<y<1}. 则Corr(X,Y)=_____.(保留至小数点后四位)
- Who is the representative of Confucians? A: Mencius B: Lao Zi C: Xun Zi D: Confucious