【简答题】对某含截距项的线性模型(3个解释变量)进行最小二乘法回归。将样本容量为60的样本按从小到大的顺序排列后,去掉中间的16个样本后再均分为两组,分别回归后Σ e i 2 =603.0148 ,Σ e 2 2 =2495.840 ,在α=95%的置信水平下判断是否存在异方差。如果存在,判断是递增还是递减的异方差。(F 0.05 (16,16)=2.35,F 0.05 (18,18)=2.19,F 0.0...
【单选题】如图所示为双踪示波器测量两个同频率正弦信号的波形,若示波器的水平(X轴)偏转因数为10μs/div,则两信号的频率和相位差分别是? 【图片】
【单选题】The foreign friends _____ here just now. [ ]
【单选题】______ Tim is poor and unfortunate, many of his friends have left him in the lurch.
【单选题】--Two Nanchang Evening papers, please! --Sorry, sir. Only one left. Would you like to have ?
【单选题】A long time __________ since he ________ Shanghai.
【单选题】某同学要统计本校图书馆最受学生欢迎的图书种类,以下是排乱的统计步骤: 1从扇形图中分析出最受学生欢迎的种类 2去图书馆收集学生借阅图书的记录 3绘制扇形图来表示各个种类所占的百分比 4整理借阅图书记录并绘制频数分布表 正确统计步骤的顺序是
【单选题】— Two Xiaogan Evening Papers, please! — Sorry, sir. Only one left. Would you like to have ______?