QNT/275 STATISTICS FOR DECISION MAKING The Latest Version A+ Study Guide ******************************************* Entire Course Link http://www.uopstudy.com/QNT-275T *******************************************
Which of the following is a violation of the independence assumption? negative autocorrelation a pattern of cyclical error terms over time positive autocorrelation a pattern of alternating error terms over time All of the other choices are correct.
A real estate company is analyzing the selling prices of residential homes in a given community. 140 homes that have been sold in the past month are randomly selected and their selling prices
are recorded. The statistician working on the project has stated that in order to perform various statistical tests, the data must be distributed according to a normal distribution. In order to determine whether the selling prices of homes included in the random sample are normally distributed, the statistician divides the data into 6 classes of equal size and records the number of observations in each class. She then performs a chi-square goodness-of-fit test for normal distribution. The results are summarized in the following table.
At a significance level of .05, what is the appropriate rejection point condition? Reject H0 if χ2> 12.5916 Reject H0 if χ2> 11.0705 Reject H0 if χ2> 9.3484 Reject H0 if χ2> 7.81473 Reject H0 if χ2> 9.48773
A real estate company is analyzing the selling prices of residential homes in a given community. 140 homes that have been sold in the past month are randomly selected and their selling prices are recorded. The statistician working on the project has stated that in order to perform various statistical tests, the data must be distributed according to a normal distribution. In order to determine whether the selling prices of homes included in the random sample are normally distributed, the statistician divides the data into 6 classes of equal size and records the number of observations in each class. She then performs a chi-square goodness-of-fit test for normal distribution. The results are summarized in the following table.
What is the appropriate null hypothesis? H0: The residential home selling prices are distributed according to a normal distribution. H0: The residential home selling prices are not distributed according to a normal distribution. H0: The distribution of residential home selling prices is either right or left skewed. H0: The distribution of the residential home selling prices is symmetric. None of the other answers is correct.
A real estate company is analyzing the selling prices of residential homes in a given community. 140 homes that have been sold in the past month are randomly selected and their selling prices are recorded. The statistician working on the project has stated that in order to perform various statistical tests, the data must be distributed according to a normal distribution. In order to determine whether the selling prices of homes included in the random sample are normally distributed, the statistician divides the data into 6 classes of equal size and records the number of observations in each class. She then performs a chi-square goodness-of-fit test for normal distribution. The results are summarized in the following table.
At a significance level of .05, we reject H0; conclude that the residential home selling prices are not distributed according to a normal distribution. do not reject H0; conclude that the residential home selling prices are not distributed according to a normal distribution. reject H0; conclude that the residential home selling prices are distributed according to a normal distribution. do not reject H0; conclude that the residential home selling prices are distributed according to a normal distribution.
When the assumption of __________ residuals (error terms) is violated, the Durbin-Watson statistic is used to test to determine if there is significant _____________ among the residuals. normality, probability independent, probability independent, autocorrelation normality, autocorrelation
In a simple regression analysis for a given data set, if the null hypothesis β = 0 is rejected, then the null hypothesis Ď = 0 is also rejected. This statement is ___________ true. always never sometimes
In performing a chi-square test of independence, as the differences between respective observed and expected frequencies _________, the probability of concluding that the row variable is independent of the column variable increases. stay the same decrease increase double
For a given data set, value of X, and confidence level, if all the other factors are constant, the confidence interval for the mean value of Y will ___________ be wider than the corresponding prediction interval for the individual value of Y. always sometimes never
When we carry out a chi-square test of independence, the alternate hypothesis states that the two relevant classifications are mutually exclusive. form a contingency table with r rows and c columns. have (r− 1)(c− 1) degrees of freedom. are statistically dependent. are normally distributed.
lass. She then performs a chi-square goodness-of-fit test for normal distribution. _____ degrees of freedom. 5 4 3 6
If the Durbin-Watson statistic is greater than (4 −dL), then we conclude that there is significant positive autocorrelation.
there is significant negative autocorrelation. there is significant autocorrelation, but we cannot identify whether it is positive or negative. the test result is inconclusive.
When a forecaster uses the ______________ method, she or he assumes that the time series components are changing slowly over time. time series regression exponential smoothing index number multiplicative decomposition
In a simple linear regression model, the slope term is the change in the mean value of y associated with _____________ in x. a corresponding increase a variable change no change a one-unit increase
When deseasonalizing a time series observation, we divide the actual time series observation by its ___________. irregular factor
cyclical factor seasonal factor weighted aggregate factor
If the errors produced by a forecasting method for 3 observations are +3, +3, and −3, then what is the mean squared error? 9 0 3 −3 2
The demand for a product for the last six years has been 15, 15, 17, 18, 20, and 19. The manager wants to predict the demand for this time series using the following simple linear trend equation: trt = 12 + 2t. What are the forecast errors for the 5th and 6th years? 0, −3 0, +3 +2, +5 −2, −5 −1, −4
The chi-square goodness-of-fit test will be valid if the average of the expected cell frequencies is ______________.
greater than 0 less than 5 between 0 and 5 at least 1 at least 5
When using simple exponential smoothing, the value of the smoothing constant Îą cannot be negative. greater than zero. greater than 1. .99. negative or greater than 1.
While a binomial distribution describes count data that can be classified into one of two mutually exclusive categories, a __________________ distribution describes count data that are classified into more than two mutually exclusive categories. normal skewed uniform multinomial
In a simple linear regression analysis, the correlation coefficient (a) and the slope (b) ___________ have the same sign. always sometimes never
The correlation coefficient may assume any value between 0 and 1. −∞ and ∞. 0 and 8. −1 and 1. −1 and 0.
XYZ Company, Annual Data
Based on the information given in the table above, what is the MAD? 1.3333 1.6667 2.5 3.3333
4.5
All of the following are forecasting methods except Holt-Winters double exponential smoothing. simple exponential smoothing. time series regression. MAD autocorrelation.
In performing a chi-square goodness-of-fit test for a normal distribution, a researcher wants to make sure that all of the expected cell frequencies are at least five. The sample is divided into 7 intervals. The second through the sixth intervals all have expected cell frequencies of at least five. The first and the last intervals have expected cell frequencies of 1.5 each. After adjusting the number of intervals, the degrees of freedom for the chi-square statistic is ____. 2 3 5 7