问题 问答题 简答题

古典线性回归模型的基本假定是什么?

答案

参考答案:

①零均值假定。即在给定xt的条件下,随机误差项的数学期望(均值)为0,即tE(u)=0。

②同方差假定。误差项tu的方差与t无关,为一个常数。

③无自相关假定。即不同的误差项相互独立。

④解释变量与随机误差项不相关假定。

⑤正态性假定,即假定误差项tu服从均值为0,方差为2的正态分布。

单项选择题
完形填空

第二部分:完型填空(共20小题;每小题1.5分,满分30分)

阅读下面短文,从短文后所给各题的四个选项(A、B、C和D)中,选出可以填入空白处的最佳选项

Have you ever had problems in your life and don’t know how to be happy? If 36, you will find “Being a Happy Teenager” by Australian writer Andrew Matthews 37.

In his book, Matthews  38  us how to have a happy life and answer the  39  of teenagers.

There are many  40  such as parents and friends, and the book  41  we should stop being angry and forgive. The book tells us of useful skills 42  how to put what you have learned into pictures of your mind to  43 your memory better.

Many teenagers think  44  happiness comes from a good exam result  45  praise (赞扬) from other people. But you can  46  be happy when there are no such “good” things.

Success comes from a(n) 47  attitude(态度). If you 48 from problems, you will have success in the future.

Some school students have  49 such as being too tall or too short. But Matthews tells us that  50 comes from thinking about things in a positive(积极的)51 . If you are  52 , people notice you and you can get a  53  view(视线) at the movie; if you are short, your clothes and shoes  54 less room in your bedroom! This is Matthews’ most important 55 : you choose to be happy!

36. A. so         B. not         C. it            D. do

37. A. wise       B. smart       C. useful        D. simple

38. A. orders      B. tells       C. asks          D. argues

39. A. problems   B. questions   C. ideas         D. comments

40. A. roles       B. classes     C. courses       D. subjects

41. A. says       B. writes      C. reads         D. thinks

42. A. for example     B. such as    C. so as      D. so that

43. A. make      B. turn         C. let           D. change

44. A. what      B. how          C. that          D. whether

45. A. and       B. but          C. so            D. or

46. A. yet       B. already      C. still         D. forever

47. A. bad       B. good         C. independent   D. normal

48. A. learn     B. rescue       C. struggle      D. separate

49. A. experiences    B. difficulties    C. fears      D. problems

50. A. success    B. happiness    C. failure       D. height

51. A. way       B. means        C. manners       D. spirit

52. A. short     B. small        C. tall          D. fat

53. A. lower     B. higher       C. worse         D. better

54. A. take      B. spend        C. cover         D. cost

55. A. work      B. lesson       C. teaching      D. study