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Question # 00004060
Subject: Statistics
Due on: 11/30/2013
Posted On: 11/25/2013 01:23 AM

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126. If X and Y have a large positive covariance and a coefficient of correlation near 1 then we can say that:

a. X and Y have a strong positive non-linear relationship

b. X and Y have a strong negative linear relationship

c. X and Y have a weak positive linear relationship

d. X and Y have a strong positive linear relationship

e. None of the above

127. The correlation coefficient is used to determine:

a. The strength of the linear relationship between x and y

b. The least squares estimates of the regression parameters

c. The predicted value of y for a given value of x

d. The coefficient of variation

e. None of the above

128. In regression analysis, the residuals represent the:

a. Difference between the actual y values and their predicted values

b. Difference between the actual x values and their predicted values

c. Square root of the coefficient of correlation

d. Change in y per unit change in x

e. None of the above

129. In simple linear regression, which of the following statements indicate no linear relationship between the variables x and y?

a. Coefficient of correlation is 1

b The correlation coefficient is 0

c. Sum of squares for error is 0

d. Covariance is relatively large

e. None of the above

130. Which of the following statements about the correlation coefficient is correct?

a. it is a number that indicates the direction of the relationship between the dependent variable y and the independent variable x

b. it is a number that indicates the strength of the relationship between the dependent variable y and the independent variable x

c. both a and b are correct

d. neither a nor b is correct

e. None of the above are correct

131. If the correlation coefficient, r, is equal to 0, then:

a. the slope of the least squares regression line is zero

b. there is no linear relationship between the dependent variable y and the independent variable x

c. the covariance will also be 0 or close to 0

d. all of the above are correct

e. None of the above are correct

132. If all data points (pairs of x and y observations) lie on a perfectly straight line sloping upwards, the correlation coefficient is equal to:

a. +1

b. -1

c. 0

d. +2

e. None of the above

133. If all data points (pairs of x and y observations) lie on a perfectly straight line sloping downwards, the correlation coefficient is equal to:

a. +1

b. -1

c. 0

d. +2

e. None of the above

134. Which of the following errors can be reduced by good randomization techniques and increasing the sample size?

a. Data acquisition error

b. Sampling error

c. Non-response error

d. Selection bias

e. None of the above

135. During a particular sampling process great care was taken to eliminate all non-sampling error. However, there will still be a difference between the population mean and the sample mean. This difference is due to

a. non-response error

b. selection bias

c. data acquisition error

d. sampling error

e. None of the above

136. Rob, a data-capturer with STATS SA, incorrectly records an age of 52 as 25. Which kind of error is this an example of?

a. sampling error

b. selection bias

c. data acquisition error

d. non-response error

e. None of the above

137. When the respondents to a questionnaire have different characteristics from those who did not choose to participate in the survey, the survey will likely suffer from which kind of error?

a. sampling error

b. selection bias

c. data acquisition error

d. non-response error

e. None of the above

138. Which of the following statements is/are correct?

a. a non-sampling error may be caused by the wording of a questionnaire

b. selection bias occurs when some respondents choose not to answer a questionnaire

c. data acquisition error occurs when a sample is not representative of the population being studied

d. all of the above statements are correct

e. None of the above

139. Which of the following errors is made when data collected in a survey is entered incorrectly by the data capturer?

a. sampling error

b. selection bias

c. data acquisition error

d. non-response error

e. None of the above

140. Which of the following exhibits the characteristics of sampling error?

a. an estimate of the average wages of 10,000 employees using a sample of 400 employees

c. a person receives a questionnaire via email and deletes it without replying

d. a data capturer enters the response to a certain question incorrectly

e. None of the above

141. Which of the following exhibits the characteristics of non-response error?

a. an estimate of the average wages of 10,000 employees using a sample of 400 employees

b. answers to the question, “Do you think the government is doing a good job on health care provision?”

c. a person receives a questionnaire via email and deletes it without replying

d. a data capturer enters the response to a certain question incorrectly

e. None of the above

142. Which of the following is/are examples of non-sampling errors?

a. errors that arise from the incorrect recording of responses

b. errors that arise when responses are not obtained from some members of the sample

c. errors that arise when some members of the target population cannot possibly be selected in the sample

d. all of the above are examples of non-sampling errors

e. None of the above

143. Which of the following errors occurs when some members of the target population cannot possibly be selected in the sample?

a. sampling error

b. selection bias

c. data acquisition error

d. non-response error

e. None of the above

144. A sample of 20 observations has a standard deviation of 3. The sum of the squared deviations of observations from the sample mean is

a. 20

b. 23

c. 29

d. 60

e. 171

145. Which measure of central location is meaningful when the data are nominal?

a. the arithmetic mean

b. the geometric mean

c. the median

d. the mode

e. both a and b

146. Which of the following are measures of the linear relationship between two variables?

a. the covariance

b. the correlation coefficient

c. the variance

d. the standard deviation

e. both a and b

147. Which of the following summary measures is most affected by outliers?

a. the median

b. the geometric mean

c. the range

d. the interquartile range

e. all the above are equally affected

148. Which of the following cannot be easily approximated from a box-and-whisker plot?

a. the range

b. the interquartile range

c. the second quartile

d. the standard deviation

e. all of
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