Quiz
STATISTICS 1
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Perguntas do quiz (30)
1The 68-95-99.7 rule applies:
- AOnly to the standard normal distribution.
- BTo any normal distribution
- CTo any probability distribution
- DNone of these answers is correct
2Mark the correct statement:
- AThe standard normal distribution has a population mean of 0, a standard deviation of 1 and a variance of 1.
- BAny normal distribution has a population mean of 0, a standard deviation of 1 and a variance of 1.
- CThe standard normal distribution is a family of different distributions depending on the mean and the dispersion of data.
- DNone of the answers is correct.
3Imagine a variable X with population mean of 0 and a variance of 1. What is the probability that the sample mean is between -3 and 3?
- AWe do not know because we have to standardize.
- B99.7%
- C68%
- D95%
4Which of the following statements is true regarding the standard error of the mean?
- AIt is equal to the population standard deviation divided by the sample size n.
- BIt is equal to the population standard deviation divided by the square root of n.
- CIt is equal to the population variance divided by the square root of n.
- DIt is equal to the population variance divided by n -1.
5If all possible random samples of size n are taken from a population, and the mean of each sample is determined, what can you say about the mean of the sample means?
- AIt is larger than the population mean.
- BIt is smaller than the population mean.
- CIt is exactly the same as the population mean.
- DNone of the above.
6If a random sample of size n is drawn from a normal population, then the sampling distribution of sample means will be:
- Anormal for all values of n.
- Bnormal only for n > 30.
- Capproximately normal for all values of n.
- Dapproximately normal only for n > 30.
7Which of the following statements is true regarding the standard error of the mean?
- AIt is equal to the population standard deviation divided by the sample size n.
- BIt is equal to the population standard deviation divided by the square root of n.
- CIt is equal to the population variance divided by the square root of n.
- DIt is equal to the population variance divided by n -1.
8If all possible random samples of size n are taken from a population, and the mean of each sample is determined, what can you say about the mean of the sample means?
- AIt is larger than the population mean.
- BIt is smaller than the population mean.
- CIt is exactly the same as the population mean.
- DNone of the above.
9Imagine a variable X with population mean of 0 and a variance of 1. What is the probability that the sample mean is between -1 and 1?
- A99.7%
- B95%
- CWe do not know because we have to standardize.
- D68%
10Unbiassedness is:
- AA desirable property of point estimators according to which the expected value of the statistic equals the parameter.
- BA desirable property of point estimators according to which the bias decreases when the sample size increases.
- CA desirable property of point estimators according to which the estimator has the smallest variance possible.
- DNone of the answers is correct.
11In inferrential statistics the estimator:
- AProvides an approximate value for the population parameter which we call estimate
- BIs a random variable (not a unique value) with which we estimate population caracteristics
- CI the random variable from which we find point estimates (by using a unique sample).
- DAll of the above are correct
12A hypothesis test:
- ATests a statement regarding a parameter (which we place in the null hypothesis) based on the sample data
- BTests a statement regarding a statistic (which we place in the alternative hypothesis) based on the sample data
- CTests a statement regarding a parameter (which we place in the alternative hypothesis) based on the sample data
- DTests a statement regarding a statistic (which we place in the null hypothesis) based on the sample data
13In a significance test, the null hypothesis:
- AAlways contains the equality sign
- BCorresponds to the statement complementary (contrary) to the problem being explored
- CMay never be accepted (we, at most, fail to reject it)
- DAll of the answers are correct
14In a significance test, the alternative hypothesis:
- ADoes not contain the equality sign
- BCorresponds to the statement complementary (contrary) to the problem being explored
- CMay never be accepted (we, at most, fail to reject it)
- DAll of the answers are correct
15Whenever we reject the null hypothesis, it means:
- AWe cannot make any conclusion regarding the alternative hypothesis.
- BWe find support for the alternative hypothesis
- CWe fail to find support for the alternative hypothesis
- DWe accept the null hypothesis
16β is
- Athe probability associated to rejecting the null hypothesis when it is true (error type I)
- Bthe probability associated to not rejecting the null hypothesis when it is true (error type II)
- Cthe probability associated to not rejecting the null hypothesis when it is false (error type II)
- Dthe probability associated to not rejecting the null hypothesis when it is true (error type I)
17If we are conducting a 2-tailed significance test for the mean (we want to test whether the mean is different from 2) and the critical value (for a 95% confidence level) is 2 whereas the standardized sample mean is 3.
- AWe cannot reject the null hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
- BWe reject the alternative hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
- CWe reject the null hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
- DWe cannot reject the null hypothesis. That is, the population mean is not significantly different from 2 at a 95% confidence level.
18If we are conducting a 2-tailed significance test for the mean (we want to test whether the mean is different from 2) and the critical value (for a 95% confidence level) is 3 whereas the standardized sample mean is 2.
- AWe cannot reject the null hypothesis. That is, the population mean is not significantly different from 2 at a 95% confidence level.
- BWe reject the alternative hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
- CWe reject the null hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
- DWe cannot reject the null hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
19α is:
- Athe probability associated to rejecting the null hypothesis when it is true (error type I)
- Bthe probability associated to not rejecting the null hypothesis when it is false (error type II)
- Cthe probability associated to not rejecting the null hypothesis when it is true (error type II)
- Dthe probability associated to not rejecting the null hypothesis when it is true (error type I)
20The following hypothesis:
μ = 4- ACan either be a null or an alternative hypotesis in a significance test
- BCannot be a hypothesis of a significance test
- CCan only be an alternative hypothesis in a significance test
- DCan only be a null hypothesis in a significance test
21If we are conducting a 1-tailed significance test for the mean (we want to test whether the mean is different from 2) and the p-value (for a 95% confidence level) is 0.027.
- AWe cannot reject the null hypothesis. That is, the population mean is not significantly different from 2 at a 95% confidence level.
- BWe cannot reject the null hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
- CWe reject the alternative hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
- DWe reject the null hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
22If we have conducted a one-tailed two-means test where we want to find if the average number of educated employees is larger in Company A than in Company B and we find that the critical value is 1,96 (at a 95% confidence level) and the standardized difference in means value is 1, we conclude that:
- AThe test can indicate which company has a significantly larger proportion of educated employees at a 95% confidence level.
- BThe average number of educated employees is significantly larger in Company A than in Company B at a 95% confidence level.
- CThere is a significant difference between the average number of educated employees in Company B and in Company A at a 95% confidence level.
- DThe average number of educated employees is not significantly larger in Company A than in Company B at a 95% confidence level.
23If we have conducted a one-tailed two-proportions test where we want to find if the proportion of educated employees is larger in Company A than in Company B and we find that the critical value is 1,96 (at a 95% confidence level) and the standardized difference in proportions is 3, we conclude that:
- AThe proportion of educated employees is significantly larger in Company B than in Company A at a 95% confidence level.
- BThere is no significant difference between the proportion of educated employees in Company B and in Company A at a 95% confidence level.
- CThe test cannot indicate which company has a significantly larger proportion of educated employees at a 95% confidence level.
- DThe proportion of educated employees is significantly larger in Company A than in Company B at a 95% confidence level.
24If we want to test whether the average grade of a Group of students increase when we compare grades at the beginning of the course and at the end, we have to conduct a:
- AOne tailed paired-samples two-means test
- BOne tailed independent samples two-means test
- CTwo tailed independent samples two-means test
- DTwo tailed paired-samples two-means test
25If we want to test whether the average grade of Group 1 is larger than the average Grade of Group 2, we will have to conduct a:
- AOne tailed paired-samples two-means test
- BTwo two tailed independent samples two-means test
- COne tailed independent samples two-means test
- DTwo tailed paired-samples two-means test
26If we have conducted a one-tailed two-means test where we want to find if the average number of educated employees is larger in Company A than in Company B and we find that the critical value is 1,96 (at a 95% confidence level) and the standardized difference in means value is 1, we conclude that:
- AThe average number of educated employees is not significantly larger in Company A than in Company B at a 95% confidence level.
- BThe average number of educated employees is significantly larger in Company A than in Company B at a 95% confidence level.
- CThe test can indicate which company has a significantly larger proportion of educated employees at a 95% confidence level
- DThere is a significant difference between the average number of educated employees in Company B and in Company A at a 95% confidence level.
27In an Independence Chi-squared test, when the critical value is smaller than the chi-squared statistic that we compute from our cross-tabulation we conclude:
- AThere is some significant association between the two variables that we have cross-tabulated.
- BWe would need to know the expected distribution to take a conclusion.
- CThere is no significant association between the two variables that we have cross-tabulated.
- DWe cannot conclude whether the variables are significantly associated or not.
28If we want to see whether a particular categorical variable with more than 2 categories follows an expected distribution, we will generally conduct:
- AThere is no test appropriate for this kind of problem
- BAn independence Chi-squared test
- CAn association test using the Chi-squared distribution
- DA goodness-of-fit chi-squared test
29In an Independence Chi-squared test, when the critical value is larger than the chi-squared statistic that we compute from our cross-tabulation we conclude:
- AWe cannot conclude whether the variables are significantly associated or not.
- BWe cannot reject that the two variables that we have cross-tabulated are independent.
- CThe two variables that we have cross-tabulated need to be not associated at any level.
- DThere is a significant association between the two variables that we have cross-tabulated.
30If we want to test whether the percentage of women in Group 1 is bigger than in Group 2 we will have to conduct:
- AA one tailed two proportions test
- BA two tailed two proportions test
- CA one tailed paired-samples two means test
- DA two tailed paired-samples two means test
Informações
- Descrição
- Quiz sobre STATISTICS 1, criado por raquel galindo em 07-06-2016.
- Autor
- raquel galindo
- Idioma
- Español
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