Which estimator is positive semi-definite?
未知类型：{'options': ['long run variance-covariance estimator [img=11x24]17de8379772258d.png[/img]=[img=51x65]17de837982326d0.png[/img]([img=17x47]17de83798f44d1a.png[/img])[img=12x24]17de83799af1362.png[/img](j)', 'OLS', 'Newey and West (1987) HAC estimator', 't test statistic'], 'type': 102}
未知类型：{'options': ['long run variance-covariance estimator [img=11x24]17de8379772258d.png[/img]=[img=51x65]17de837982326d0.png[/img]([img=17x47]17de83798f44d1a.png[/img])[img=12x24]17de83799af1362.png[/img](j)', 'OLS', 'Newey and West (1987) HAC estimator', 't test statistic'], 'type': 102}
举一反三
- 已知直线DE与平面P、ABC平行，求de、d'e'.[img=382x414]17e4438c9b183d9.png[/img] 未知类型：{'options': ['', ' [img=408x441]17e4438cb2384bd.png[/img]', ' [img=425x404]17e4438cbcd417a.png[/img]', ' 以上均不对'], 'type': 102}
- 已知随机变量X的分布列如下：[img=386x130]17e43ec4c459e73.png[/img]，则E(X)= A: 17/30 B: m未知，无法求出 C: -30/17 D: -17/30
- About the formula V =[img=73x62]180300d897d52ad.png[/img], which statement is NOT correct? A: [img=12x19]180300d8a0ab3df.png[/img](0) is positive semi-definite B: V is positive semi-definite C: [img=12x19]180300d8a0ab3df.png[/img](j) → 0 as j →∞ D: [img=12x19]180300d8a0ab3df.png[/img](j) =[img=12x19]180300d8a0ab3df.png[/img](-j)
- 已知函数f(x)=[img=163x48]17e0bf90d5bf980.png[/img]函数f(x)在哪一点连续( ) 未知类型：{'options': ['处处连续', ' x=1', ' x=0', ' x=[img=15x39]17e0b46938bc6fc.png[/img]'], 'type': 102}
- 已知直线DE与平面ABC平行，求d'e'。[img=392x361]17e4438c6b686dd.png[/img] 未知类型：{'options': ['', ' [img=404x389]17e4438c8468229.png[/img]', ' [img=393x353]17e4438c8ea295f.png[/img]', ' 以上均不对'], 'type': 102}