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起止时间:2020-10-14到2021-01-25
更新状态:已完结
Part 1： Basic Statistics： Chapter 1 Estimation： Confidence intervals Test 1
1、 When estimating population parameters, a point estimate is:
A:A range of possible values for a population parameter.
B:Always equal to a population value.
C:A statistic that estimates a population parameter.
D:The population mean.
答案: A statistic that estimates a population parameter.
2、 A characteristic of all confidence intervals is that:
A:a confidence interval always includes the population parameter.
B:a confidence interval always increases in width as the sample size is increased.
C:a confidence interval cannot include a value of 0.
D:a confidence interval always increases in width as the level of confidence increases.
答案: a confidence interval always increases in width as the level of confidence increases.
3、 If we wish to decrease the width (increase the precision) of a confidence interval, we would:
A:increase the size of the sample.
B:reduce the size of the population.
C:raise the level of confidence.
D:compute the mean.
答案: increase the size of the sample.
4、 We wish to develop a confidence interval for the population mean. The population standard deviation is known. We have a sample of 40 observations. We decide to use the 92 percent level of confidence. The appropriate value of z is:
A:1.75.
B:1.96.
C:1.65.
D:2.58.
答案: 1.75.
5、 We wish to develop a confidence interval for the population mean. The population follows the normal distribution, the standard deviation of the population is 3, and we have a sample of 10 observations. We decide to use the 90 percent level of confidence. The appropriate statistic for the level of confidence is:
A:z = 1.645.
B:z = 1.960.
C:t = 1.833.
D:t = 2.262.
答案: z = 1.645.
6、 The fraction of a sample possessing a certain trait is called a:
A:proportion.
B:population.
C:mean.
D:confidence interval.
答案: proportion.
7、 To develop a confidence interval for a proportion:
A:we approximate the binomial distribution with a normal distribution.
B:the sample size should be at least 100.
C:p should be less than .05.
D:we use the t statistic.
答案: we approximate the binomial distribution with a normal distribution.
8、 We wish to develop a confidence interval for the population mean. The population follows the normal distribution and the population standard deviation is 3. We collect a random sample of 10 observations. We decide to use the 90 percent level of confidence. The margin of error for the confidence interval is:
A:± 1.565.
B:± 1.645.
C:± 2.262.
D:± 2.146.
答案: ± 1.565.
9、 We wish to develop a confidence interval for the population mean. The population follows the normal distribution. We collect a random sample of 10 observations and the sample standard deviation is 3. We decide to use the 95 percent level of confidence. The margin of error for the confidence interval is:
A:± 2.146.
B:± 1.859.
C:± 1.960.
D:± 2.262.
答案: ± 2.146.
10、 Which of the following statements is a characteristic of the t distribution?
A:It is a continuous distribution.
B:It is a discrete distribution.
C:It has a mean of 0.
D:It is symmetrical.
答案: It is a continuous distribution.;
It has a mean of 0.;
It is symmetrical.
Part 1： Basic Statistics：Chapter 2 Hypothesis Testiing Test 2
1、 For a null hypothesis statement, it always includes:
A:a hypothesized value for the sample statistic.
B:a statement of equality: (=), (≤) or (≥).
C:a statement of less than: (<).
D:a statement of greater than: (>).
答案: a statement of equality: (=), (≤) or (≥).
2、 Which of the following statements is true about the alternate hypothesis?
A:It is accepted if the null hypothesis is rejected.
B:It will always contain an equal sign.
C:It is rejected if the null hypothesis is true.
D:It is accepted if the null hypothesis is accepted.
答案: It is accepted if the null hypothesis is rejected.
3、 A Type I Error is:
A:calculated from sample information.
B:a probability determined from the test statistic.
C:the probability of rejecting the null hypothesis when it is true.
D:the probability of accepting the null hypothesis when it is false.
答案: the probability of rejecting the null hypothesis when it is true.
4、 When testing a null hypothesis, a critical value is:
A:calculated from sample information.
B:always positive.
C:the point that divides the acceptance region from the rejection region.
D:a probability determined from the test statistic.
答案: the point that divides the acceptance region from the rejection region.
5、 In a one-tailed hypothesis test:
A:the rejection region is in only one of the tails of a distribution.
B:the rejection region is split between the tails of a distribution.
C:the area of the rejection region equals the p-value.
D:the area of the rejection region is twice the value of the p-value.
答案: the rejection region is in only one of the tails of a distribution.
6、 To use a z statistic in a one-sample hypothesis test of a mean, we need to know:
A:the population mean.
B:the population standard deviation.
C:the degrees of freedom.
D:the margin of error.
答案: the population standard deviation.
7、 A p-value is equal to the:
A:population proportion.
B:significance level.
C:fraction of the population that has a particular characteristic.
D:probability of finding a value of the test statistic that is equal or more extreme (greater than or less than) than the value of the test statistic assuming the null hypothesis is true.
答案: probability of finding a value of the test statistic that is equal or more extreme (greater than or less than) than the value of the test statistic assuming the null hypothesis is true.
8、 A Type II Error occurs when we:
A:accept the null hypothesis when it is false.
B:reject the alternate hypothesis when it is true.
C:reject the null hypothesis when it is false.
D:accept the null hypothesis when it is true.
答案: accept the null hypothesis when it is false.
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