5685537
Description
Quiz by raquel galindo, updated more than 1 year ago
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Created by raquel galindo
over 8 years ago
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Question 1
Question
The 68-95-99.7 rule applies:
Answer
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Only to the standard normal distribution.
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To any normal distribution
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To any probability distribution
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None of these answers is correct
Question 2
Question
Mark the correct statement:
Answer
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The standard normal distribution has a population mean of 0, a standard deviation of 1 and a variance of 1.
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Any normal distribution has a population mean of 0, a standard deviation of 1 and a variance of 1.
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The standard normal distribution is a family of different distributions depending on the mean and the dispersion of data.
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None of the answers is correct.
Question 3
Question
Imagine 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?
Answer
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We do not know because we have to standardize.
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99.7%
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68%
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95%
Question 4
Question
Which of the following statements is true regarding the standard error of the mean?
Answer
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It is equal to the population standard deviation divided by the sample size n.
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It is equal to the population standard deviation divided by the square root of n.
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It is equal to the population variance divided by the square root of n.
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It is equal to the population variance divided by n -1.
Question 5
Question
If 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?
Answer
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It is larger than the population mean.
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It is smaller than the population mean.
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It is exactly the same as the population mean.
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None of the above.
Question 6
Question
If a random sample of size n is drawn from a normal population, then the sampling distribution of sample means will be:
Answer
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normal for all values of n.
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normal only for n > 30.
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approximately normal for all values of n.
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approximately normal only for n > 30.
Question 7
Question
Which of the following statements is true regarding the standard error of the mean?
Answer
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It is equal to the population standard deviation divided by the sample size n.
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It is equal to the population standard deviation divided by the square root of n.
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It is equal to the population variance divided by the square root of n.
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It is equal to the population variance divided by n -1.
Question 8
Question
If 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?
Answer
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It is larger than the population mean.
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It is smaller than the population mean.
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It is exactly the same as the population mean.
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None of the above.
Question 9
Question
Imagine 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?
Answer
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99.7%
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95%
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We do not know because we have to standardize.
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68%
Question 10
Question
Unbiassedness is:
Answer
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A desirable property of point estimators according to which the expected value of the statistic equals the parameter.
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A desirable property of point estimators according to which the bias decreases when the sample size increases.
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A desirable property of point estimators according to which the estimator has the smallest variance possible.
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None of the answers is correct.
Question 11
Question
In inferrential statistics the estimator:
Answer
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Provides an approximate value for the population parameter which we call estimate
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Is a random variable (not a unique value) with which we estimate population caracteristics
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I the random variable from which we find point estimates (by using a unique sample).
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All of the above are correct
Question 12
Question
A hypothesis test:
Answer
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Tests a statement regarding a parameter (which we place in the null hypothesis) based on the sample data
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Tests a statement regarding a statistic (which we place in the alternative hypothesis) based on the sample data
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Tests a statement regarding a parameter (which we place in the alternative hypothesis) based on the sample data
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Tests a statement regarding a statistic (which we place in the null hypothesis) based on the sample data
Question 13
Question
In a significance test, the null hypothesis:
Answer
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Always contains the equality sign
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Corresponds to the statement complementary (contrary) to the problem being explored
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May never be accepted (we, at most, fail to reject it)
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All of the answers are correct
Question 14
Question
In a significance test, the alternative hypothesis:
Answer
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Does not contain the equality sign
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Corresponds to the statement complementary (contrary) to the problem being explored
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May never be accepted (we, at most, fail to reject it)
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All of the answers are correct
Question 15
Question
Whenever we reject the null hypothesis, it means:
Answer
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We cannot make any conclusion regarding the alternative hypothesis.
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We find support for the alternative hypothesis
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We fail to find support for the alternative hypothesis
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We accept the null hypothesis
Question 16
Question
β is
Answer
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the probability associated to rejecting the null hypothesis when it is true (error type I)
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the probability associated to not rejecting the null hypothesis when it is true (error type II)
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the probability associated to not rejecting the null hypothesis when it is false (error type II)
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the probability associated to not rejecting the null hypothesis when it is true (error type I)
Question 17
Question
If 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.
Answer
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We cannot reject the null hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
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We reject the alternative hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
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We reject the null hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
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We cannot reject the null hypothesis. That is, the population mean is not significantly different from 2 at a 95% confidence level.
Question 18
Question
If 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.
Answer
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We cannot reject the null hypothesis. That is, the population mean is not significantly different from 2 at a 95% confidence level.
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We reject the alternative hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
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We reject the null hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
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We cannot reject the null hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
Question 19
Question
α is:
Answer
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the probability associated to rejecting the null hypothesis when it is true (error type I)
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the probability associated to not rejecting the null hypothesis when it is false (error type II)
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the probability associated to not rejecting the null hypothesis when it is true (error type II)
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the probability associated to not rejecting the null hypothesis when it is true (error type I)
Question 20
Question
The following hypothesis:
μ = 4
Answer
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Can either be a null or an alternative hypotesis in a significance test
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Cannot be a hypothesis of a significance test
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Can only be an alternative hypothesis in a significance test
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Can only be a null hypothesis in a significance test
Question 21
Question
If 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.
Answer
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We cannot reject the null hypothesis. That is, the population mean is not significantly different from 2 at a 95% confidence level.
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We cannot reject the null hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
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We reject the alternative hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
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We reject the null hypothesis. That is, the population mean is significantly different from 2 at a 95% confidence level.
Question 22
Question
If 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:
Answer
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The test can indicate which company has a significantly larger proportion of educated employees at a 95% confidence level.
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The average number of educated employees is significantly larger in Company A than in Company B at a 95% confidence level.
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There is a significant difference between the average number of educated employees in Company B and in Company A at a 95% confidence level.
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The average number of educated employees is not significantly larger in Company A than in Company B at a 95% confidence level.
Question 23
Question
If 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:
Answer
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The proportion of educated employees is significantly larger in Company B than in Company A at a 95% confidence level.
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There is no significant difference between the proportion of educated employees in Company B and in Company A at a 95% confidence level.
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The test cannot indicate which company has a significantly larger proportion of educated employees at a 95% confidence level.
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The proportion of educated employees is significantly larger in Company A than in Company B at a 95% confidence level.
Question 24
Question
If 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:
Answer
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One tailed paired-samples two-means test
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One tailed independent samples two-means test
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Two tailed independent samples two-means test
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Two tailed paired-samples two-means test
Question 25
Question
If 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:
Answer
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One tailed paired-samples two-means test
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Two two tailed independent samples two-means test
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One tailed independent samples two-means test
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Two tailed paired-samples two-means test
Question 26
Question
If 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:
Answer
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The average number of educated employees is not significantly larger in Company A than in Company B at a 95% confidence level.
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The average number of educated employees is significantly larger in Company A than in Company B at a 95% confidence level.
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The test can indicate which company has a significantly larger proportion of educated employees at a 95% confidence level
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There is a significant difference between the average number of educated employees in Company B and in Company A at a 95% confidence level.
Question 27
Question
In 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:
Answer
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There is some significant association between the two variables that we have cross-tabulated.
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We would need to know the expected distribution to take a conclusion.
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There is no significant association between the two variables that we have cross-tabulated.
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We cannot conclude whether the variables are significantly associated or not.
Question 28
Question
If we want to see whether a particular categorical variable with more than 2 categories follows an expected distribution, we will generally conduct:
Answer
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There is no test appropriate for this kind of problem
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An independence Chi-squared test
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An association test using the Chi-squared distribution
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A goodness-of-fit chi-squared test
Question 29
Question
In 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:
Answer
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We cannot conclude whether the variables are significantly associated or not.
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We cannot reject that the two variables that we have cross-tabulated are independent.
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The two variables that we have cross-tabulated need to be not associated at any level.
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There is a significant association between the two variables that we have cross-tabulated.
Question 30
Question
If we want to test whether the percentage of women in Group 1 is bigger than in Group 2 we will have to conduct:
Answer
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A one tailed two proportions test
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A two tailed two proportions test
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A one tailed paired-samples two means test
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A two tailed paired-samples two means test
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