开发者:上海品职教育科技有限公司 隐私政策详情

应用版本:4.2.11(IOS)|3.2.5(安卓)APP下载

许诺 · 2020年09月15日

问一道题:NO.PZ2018062016000140

问题如下:

During the table below, the mean monthly return of X Index in the first five years have been different than the mean return in the second five years.

Let the μ1 stand for the population mean return for the year1 through year 5 and μ2 stand for the population mean return for the year 6 through year 10, the following hypothese: H0: μ1 – μ2 = 0 versus Ha: μ1 – μ2 ≠ 0

Assume that the significant level is 0.05

Which of the following options is most accurate?

选项:

A.

The null hypothesis will be rejected if t<-1.98 or t>1.98.

B.

The t-test has 119 degrees of freedom.

C.

The rejection points are ±1.658.

解释:

A is correct. The two samples are drawn from two different time periods, so they are independent samples. The population variances can be assumed to be equal. Under all considerations, the t-test has 60+60-2=118 degrees of freedom.For a two-tailed test, at the significant level of 0.05, the rejection points are ±1.980, so we will reject the null if t<-1.980 or t>1.980.

老师,请问关于B选项,两个总体的方差算出来分别为20.052和17.131,是不相等的,为什么作出方差相等的假设呢?

1 个答案

星星_品职助教 · 2020年09月15日

同学你好,

这道题目总体的方差是不知道的,题干给出的所有信息都是样本的。所以才用t检验,t检验的前提是总体方差未知。

如果这道题的两个总体方差已经确切的知道了,就没有去做假设检验的必要了

  • 1

    回答
  • 0

    关注
  • 364

    浏览
相关问题

NO.PZ2018062016000140问题如下ring the table below, the memonthly return of X Inx in the first five years have been fferent ththe mereturn in the seconfive years.Let the μ1 stanfor the population mereturn for the year1 through ye5 anμ2 stanfor the population mereturn for the ye6 through ye10, the following hypothese: H0: μ1 – μ2 = 0 versus Hμ1 – μ2 ≠ 0 Assume ththe significant level is 0.05Whiof the following options is most accurate?A.The null hypothesis will rejecteif t -1.98 or t 1.98. B.The t-test h119 grees of freem. C.The rejection points are ±1.658.A is correct. The two samples are awn from two fferent time perio, so they are inpennt samples. The population variances cassumeto equal. Unr all consirations, the t-test h60+60-2=118 grees of freem.For a two-tailetest, the significant level of 0.05, the rejection points are ±1.980, so we will rejethe null if t -1.980 or t 1.980.谢谢谢。。。。。。。

2023-06-23 17:16 1 · 回答

NO.PZ2018062016000140 问题如下 ring the table below, the memonthly return of X Inx in the first five years have been fferent ththe mereturn in the seconfive years.Let the μ1 stanfor the population mereturn for the year1 through ye5 anμ2 stanfor the population mereturn for the ye6 through ye10, the following hypothese: H0: μ1 – μ2 = 0 versus Hμ1 – μ2 ≠ 0 Assume ththe significant level is 0.05Whiof the following options is most accurate? A.The null hypothesis will rejecteif t -1.98 or t 1.98. B.The t-test h119 grees of freem. C.The rejection points are ±1.658. A is correct. The two samples are awn from two fferent time perio, so they are inpennt samples. The population variances cassumeto equal. Unr all consirations, the t-test h60+60-2=118 grees of freem.For a two-tailetest, the significant level of 0.05, the rejection points are ±1.980, so we will rejethe null if t -1.980 or t 1.980. 为什么是t分布呢

2022-11-09 17:08 1 · 回答

NO.PZ2018062016000140 问题如下 ring the table below, the memonthly return of X Inx in the first five years have been fferent ththe mereturn in the seconfive years.Let the μ1 stanfor the population mereturn for the year1 through ye5 anμ2 stanfor the population mereturn for the ye6 through ye10, the following hypothese: H0: μ1 – μ2 = 0 versus Hμ1 – μ2 ≠ 0 Assume ththe significant level is 0.05Whiof the following options is most accurate? A.The null hypothesis will rejecteif t -1.98 or t 1.98. B.The t-test h119 grees of freem. C.The rejection points are ±1.658. A is correct. The two samples are awn from two fferent time perio, so they are inpennt samples. The population variances cassumeto equal. Unr all consirations, the t-test h60+60-2=118 grees of freem.For a two-tailetest, the significant level of 0.05, the rejection points are ±1.980, so we will rejethe null if t -1.980 or t 1.980. 由于拒绝原假设的原则为|t-statistic|>|criticvalue|,可知A正确。請問|t-statistic|為多少?這題如何計算,謝謝,

2022-05-08 00:05 1 · 回答

NO.PZ2018062016000140问题如下ring the table below, the memonthly return of X Inx in the first five years have been fferent ththe mereturn in the seconfive years.Let the μ1 stanfor the population mereturn for the year1 through ye5 anμ2 stanfor the population mereturn for the ye6 through ye10, the following hypothese: H0: μ1 – μ2 = 0 versus Hμ1 – μ2 ≠ 0 Assume ththe significant level is 0.05Whiof the following options is most accurate?A.The null hypothesis will rejecteif t -1.98 or t 1.98. B.The t-test h119 grees of freem. C.The rejection points are ±1.658.A is correct. The two samples are awn from two fferent time perio, so they are inpennt samples. The population variances cassumeto equal. Unr all consirations, the t-test h60+60-2=118 grees of freem.For a two-tailetest, the significant level of 0.05, the rejection points are ±1.980, so we will rejethe null if t -1.980 or t 1.980.可以詳細講一下做題思路嗎

2022-04-04 17:00 3 · 回答

NO.PZ2018062016000140 The t-test h119 grees of freem. The rejection points are ±1.658. A is correct. The two samples are awn from two fferent time perio, so they are inpennt samples. The population variances cassumeto equal. Unr all consirations, the t-test h60+60-2=118 grees of freem.For a two-tailetest, the significant level of 0.05, the rejection points are ±1.980, so we will rejethe null if t1.980. 为什么是T分布不是Z分布呢 从题干哪里可以判断哇

2022-03-21 14:03 1 · 回答