Q&A Hero

Q: The Wilcoxon signed rank test is always a one-tail test with the rejection region in the upper tail.

Q: All Wilcoxon signed rank tests are two-tailed tests since we are testing whether the population median is the exact center of the population distribution.

Q: The following null and alternative hypotheses are appropriate when using a Wilcoxon signed rank test. H0 : Population Median equals 14.5 HA : Population Median is not equal to 14.5

Q: If a decision maker believes that the population is normally distributed and the data are known to be ratio level, then the either the t-test or the Wilcoxon signed rank test can be used to test null hypotheses about a single population mean.

Q: The Wilcoxon signed rank test should be used in place of the t-test whenever the sample size is less than 20.

Q: The basic logic of the Wilcoxon signed rank test is that if about half the data values fall above the hypothesized median, and about half fall below, the null hypothesis should not be rejected.

Q: The Wilcoxon signed rank test is used to test hypotheses about the population median.

Q: The Wilcoxon signed rank test is used for testing hypotheses about a population median if the data are at nominal level.

Q: Under what conditions should a decision maker use a nonparametric statistical procedure?

Q: A survey was recently conducted in which random samples of car owners of Chrysler, GM, and Ford cars were surveyed to determine their satisfaction. Each owner was asked to rate overall satisfaction on a scale of 1 (poor) to 1000 (excellent). The following data were recorded: Chrysler GM Ford 650 400 700 700 800 750 500 500 650 800 400 800 900 600 900 750 900 700 If the analysts are not willing to assume that the population ratings are normally distributed and will use the Kruskal-Wallis test to determine if the three companies have different median ratings, what is the correct conclusion if the test is to be conducted using an alpha = .05 level? A) H0should be rejected and we conclude that there is no significant difference between the 3 companies. B) H0should not be rejected and we conclude that there is no significant difference between the 3 companies. C) H0should be rejected and we conclude that there is a significant difference between the 3 companies. D) H0should not be rejected and we conclude that there is a significant difference between the 3 companies.

Q: If we are interested in testing to determine whether the center of three or more populations is equal when the data in the samples are ordinal, what is the appropriate test to conduct? A) A t-test B) An ANOVA C) A Kruskal-Wallis D) A Wilcoxon Matched-Pairs Sign Rank test

Q: Assume that 4 populations are to be compared using a Kruskal-Wallis one-way analysis of variance. What is the critical value using a 0.05 level of significance? A) 5.9915 B) 6.2514 C) 7.8147 D) 9.4877

Q: In a Kruskal-Wallis test when ties occur, each observation is given the ________ for which it is tied. A) highest rank B) lowest rank C) mean rank D) median rank

Q: The Kruskal-Wallis test is usually limited to comparing sample values from ________ or more populations. A) 2 B) 3 C) 4 D) 5

Q: Which of the following is not an assumption of the Kruskal-Wallis one-way analysis of variance? A) Variables have a continuous distribution. B) Samples are independent. C) Sample sizes are equal for all populations. D) Population distributions are identical except for possible differences in center.

Q: In conducting a Kruskal-Wallis one-way analysis of variance, the test statistic is assumed to have approximately which distribution when the null hypothesis is true? A) A t-distribution B) An F-distribution C) A normal distribution D) A chi-square distribution

Q: If a Mann-Whitney U test was performed and U1= 50 and U2= 40, if the sample from population 1 was 10, the sample size from population 2 was: A) 10 B) 15 C) 9 D) Can't be determined without more information.

Q: When employing a small sample Mann-Whitney U test for a two-tailed test, which of the following is true? A) The sample sizes need to be equal. B) Select as the test statistic the smaller of the two U values. C) Select either of the U values to be the test statistic. D) The alpha level should be doubled.

Q: The Wilcoxon matched-pairs signed rank test assumes that the two samples are: A) equal in size. B) independent and random. C) paired. D) Both A and C

Q: The Mann-Whitney U test assumes that the 2 samples are: A) equal in size. B) independent and random. C) matched or paired. D) normally distributed.

Q: If a two-tailed Wilcoxon Matched-Pairs Signed Rank test is conducted for a sample of n = 8 and an alpha level equal to .05, the critical value is: A) 4 B) 1.96 C) 30 D) 2

Q: If we wish to test whether two related populations have equal medians, an appropriate nonparametric test to use is: A) the Mann-Whitney U test. B) the Kruskal-Wallis test. C) the Wilcoxon signed rank test. D) the Wilcoxon matched-pairs signed rank test.

Q: Assume that you are conducting a small sample Mann-Whitney U test where n1= 14 and n2= 16 and that U1= 98. Assuming that U1has been found correctly, what is the value of U2? A) 112 B) 126 C) 224 D) Insufficient information to determine U2.

Q: Recently, a legislative committee commissioned a study of incomes in a western state. At issue was whether the ratings of the legislature's performance differed between rural citizens and city residents. A random sample of 25 city residents and 35 rural residents was asked to rate the performance of the legislature on a scale of 1 to 100. The analysts believe that the population distribution of ratings would be highly skewed so they decided to use the Mann-Whiney U test to test whether there is a difference in median ratings by the two groups. Given this information, which of the following is the correct critical value if the test is to be conducted at the .10 level of significance? A) z = 1.96 B) t = 2.0357 C) U = 437.5 D) z = 1.645

Q: In a large sample Mann-Whitney U test in which the sample size from the first population is 30 and the sample size from the second population is 40, which of the following is the expected U value if the null hypothesis of equal median values is true? A) 1,200 B) 70 C) 35 D) 600

Q: Consider the situation in which a human resources manager wishes to determine whether the median number of days of sick leave per year is greater for female employees than for male employees. The following data represent random samples of males and females: Males Females 5 14 10 5 0 13 9 7 2 8 7 0 5 7 10 10 3 6 1 5 If the manager is unwilling to assume that the populations are normally distributed, which of the following is the correct conclusion to reach if the test is conducted using a .05 level of significance? A) Reject the null hypothesis B) Conclude that females do have a higher median than males C) Do not reject the null hypothesis D) Conclude that males have a higher median than females

Q: Assume you are conducting a two-tailed Mann-Whitney U test for a small sample and have found that U1= 58 and U2= 86. What is the value of the test statistic? A) 58 B) 86 C) 72 D) 144

Q: Under what circumstances should the standard normal distribution be used when employing the Mann-Whitney U test? A) When the sample sizes are equal from the two populations B) When the sample sizes are greater than 20 C) When the populations are normally distributed D) You would never use the standard normal distribution.

Q: Consider the situation in which a study was recently conducted to determine whether the median price of houses is the same in Seattle and Phoenix. The following data were collected. Seattle Phoenix 233,000 309,000 567,800 422,000 145,600 209,000 234,000 187,000 356,000 165,000 203,000 189,000 Given these data, if a Mann-Whitney U test is to be used, the test statistic is: A) 22 B) 14 C) approximately 1.96 D) 34

Q: Which of the following is not an assumption of the Mann-Whitney U test? A) The sample sizes are equal. B) The samples are independent. C) The value measured is continuous. D) The population distributions are the same for shape and spread.

Q: When the Mann-Whitney U test is performed, which of the following is true? A) We assume that the populations are normally distributed. B) We are interested in testing whether the medians from two populations are equal. C) The data are nominal level. D) The samples are independent.

Q: A marketing firm is interested to know whether the median age of college students is 21 years. A sample of 80 college students is taken. Thirty of the students were under 21, 45 of the students were over 21, and 10 were 21 years old. The conclusion is that A) the median age of college students is significantly different from 21. B) the median age of college students is not significantly different from 21. C) the median age of college students is significantly older than from 21. D) the median age of college students is significantly younger than from 21.

Q: Which of the following tests would not be an example of nonparametric method? A) Wilcoxon signed-rank test B) Mann-Whitney U-Test C) Kruskal-Wallis One-Way Analysis of Variance D) χ2test

Q: In the finding the critical value for the Wilcoxon signed rank test, what does "n" represent? A) The number of observations in the sample B) The number of pairs C) The number of nonzero deviations D) The number of positive ranks

Q: The General Electric service department believes that the median time for a service call should be 30 or fewer minutes. To test this, the following random sample of service times was collected: Time 33 27 40 34 22 19 40 73 26 Given that the managers do not wish to make the assumption that the population is normally distributed, the test statistic for the Wilcoxon signed rank sum test is: A) W = 43.0 B) W = 27.0 C) W = 18.0 D) None of the above

Q: The Wilcoxon signed rank test is used to test which of the following type of hypotheses? A) Tests about a single population median B) Tests involving three or more population medians C) Tests about the variances of two or more populations D) Tests about two or more population proportions

Q: Which of the following is not a step involved in the Wilcoxon signed rank test? A) Find the deviations from the hypothesized median B) Rank the deviations C) Convert the deviations to absolute values D) Find the deviations from the sample median

Q: In analyzing a forecast model, what is the main advantage of using the MAD instead of the MSE?

Q: Given the following time series data:and using smoothing constants of alpha = 0.3, the exponential smoothing forecast for time period 3 isA) 18B) 19.2C) 20D) 40

Q: The Wilson Company is interested in forecasting demand for its XG-667 product for quarter 13 based on 12 quarters of data. The following shows the data and the double exponential smoothing model results for periods 1-12 using alpha = 0.20 and beta = 0.40.Based on this information, which of the following statements is true?A) If beta is changed to 0.20 and alpha remains at 0.20, the MAD for periods 2-12 is reduced.B) If beta is changed to 0.20 and alpha remains at 0.20, the forecast for period 13 is slightly reduced.C) The forecast bias for periods 2-12 is approximately 6.18.D) All of the above are true.

Q: The Zocor Company is interested in forecasting period 13 sales for a product. It has 12 months of historical data. The following shows the data and the forecasted values for periods 1-12 using a single exponential smoothing model with a smoothing constant value equal to 0.20What is the forecast bias value for the model over periods 2-12?A) About 8.7B) Approximately -11.9C) About 8.9D) None of the above

Q: A time series is shown below. Perform single exponential smoothing for this data set using α = 0.2What is the value of the forecast for period 6?A) 40B) 36C) 31.5D) 33.2

Q: Under which of the following conditions would you suggest that a double exponential smoothing model should be used instead of a single exponential smoothing model? A) When the time-series data exhibit a trend B) When there are two main time-series variables involved in the forecast application C) When the data exhibit only random variation D) When the data set is extremely uneven

Q: Which of the following approaches might be used to determine which value for the smoothing constant to use in a single exponential smoothing model? A) Select the value that produces the smallest MAD value B) Select the value that maximizes the MSE C) Use the value that gives the largest MAD value D) Use the value that smoothes the data the most

Q: In a simple exponential smoothing model, which of the following statements is true? A) The forecast values are determined by computing a moving average of the previous 4 data periods if we are working with quarterly data. B) The larger the smoothing constant, the more smoothing that takes place in the model. C) If the data contain a lot of random or irregular ups and downs, then a larger smoothing constant should be used in an attempt to model these fluctuations. D) More smoothing of the data will take place if a smoothing constant value close to zero is used.

Q: Which of the following forecasting methods allows the decision maker to weigh the past time series differently to make the model more sensitive to more recent data? A) Linear trend regression model B) Moving average model C) Exponential smoothing D) Deseasonalizing the time series

Q: The most useful tool to identify the trend component of a time series is A) moving averages. B) exponential smoothing. C) regression analysis. D) the MAD approach.

Q: A company has developed a linear trend regression model based on 16 quarters of data. The independent variable is the measure of time (t = 1 thru 16 where quarter 1 is winter quarter, 2 is spring, etc.). The company has also developed seasonal indexes for each quarter as follows:The linear trend forecast equation is: Given this information, which of the four quarters beginning next winter (period t = 17) will have the highest seasonally adjusted forecast?A) WinterB) SpringC) SummerD) Fall

Q: The Boxer Company has been in business since 1998. The following sales data are recorded by quarter for the years 2010-2012.The managers at the company wish to determine the seasonal indexes for each quarter during the year. The index for the summer quarter is:A) approximately 1.39B) less than 1.1C) about 087D) approximately 159

Q: Which of the following is true about deseasonalizing data? A) The sum of the seasonal indexes should be 1.0. B) The time series is deseasonalized by multiplying each value by its seasonal index. C) Deseasonalizing a time series reduces autocorrelation. D) Deseasonalizing a time series can make it easier to see a trend.

Q: If time-series data exhibit a seasonal pattern, which of the following approaches could be used to compute season indexes? A) The exponential smoothing technique B) The multiplicative model D) None of the above Answer: B

Q: After a linear forecasting model is found for a time series, if the Durbin-Watson statistic is less than dLthis means that: A) no positive autocorrelation exists, the linear model is adequate. B) positive autocorrelation exists, a nonlinear model should be tried. C) no positive autocorrelation exists, a nonlinear model should be tried. D) positive autocorrelation exists, the linear model is adequate.

Q: Suppose an economist has developed a model for forecasting annual consumption, yt, as function of total labor income, x1t, and total property income, x2tbased on 20 years on annual data. The following regression model has been developed: t = 7.81 + 0.91x1t + 0.57x2twith the standard error = 1.29 and the Durbin-Watson d statistic = 2.09. Using an alpha = .05, which of the following conclusions should be reached? A) Conclude that no positive autocorrelation exists B) Conclude that significant positive autocorrelation exists C) Uncertain whether positive or negative autocorrelation exists D) No significant autocorrelation exists.

Q: Which of the following statements about the Durbin-Watson d statistic is true? A) It can assume any value between 0 and 4. B) It may assume any value between -4 and + 4. C) It may assume any positive value. D) It has a maximum value of 2.

Q: If you suspect that your trend forecasting model may have autocorrelated forecast errors, which the following should you compute? A) The MAD B) The standard error of the estimate C) The Durbin-Watson test statistic D) The correlation coefficient

Q: Which of the following is true about forecast bias? A) It is the mean absolute deviation. B) It is equal to the square root of the MSE. C) When it is negative it means that the forecasts tended to be high. D) When it is positive it means that the forecasts tended to be high.

Q: The following output is provided for a linear trend regression-based forecasting model based on 12 months of data:Suppose that the actual sales for months 13-15 are: 720, 680, 800. Given this, which of the following is the forecast bias value for months 13-15?A) Approximately 77.7B) Approximately 233.2C) About -56.8D) Just under 80

Q: Which of the following is true regarding the MSE and MAD in forecasting? A) The MAD will tend to be a larger value than the MSE. B) The MSE is much more useful than the MAD. C) The square root of the MSE provides a value that will be similar to the MAD. D) The MAD will be equal to the MSE.

Q: A company has developed a linear trend model to forecast monthly sales. The following data show the actual sales and the "fitted" sales for months 1-12.Based on these data, what is the value for the mean absolute deviation for months 1-12?A) Approximately 975B) About 81C) Nearly 150D) None of the above

Q: Which of the following statistical measures is used to help decision makers assess the potential for their model to provide usable forecasts? A) The mean absolute deviation B) The mean square error C) Both A and B D) Neither A nor B

Q: A company has recorded the 12 months of sales data for the past year. It wishes to use the regression approach to develop a trend-based approach for forecasting future months. The following data are provided:Based on this information, which of the following is forecast for month 15?A) Approximately 692B) About 596C) Just over 825D) None of the above

Q: A company has recorded 12 months of sales data for the past year and has found the linear trend equation is = 286 + 64.9t. Based on this information, which of the following is the forecast for period 13? A) 3718 B) 842.4 C) 350.8 D) 1129.7

Q: If a company has 12 years of annual sales data and is in need of a three-year forecast, which of the following forecasting techniques might be useful? A) Forecast generalization B) Seasonality processing C) Regression-based trend forecasting D) Random component analysis

Q: A company has recorded annual sales for the past 14 years and found the following linear trend model:. This means that:A) on average sales are increasing by of 5.23 per year.B) on average sales are increasing by of 144.6 per year.C) there is a seasonal component in the data.D) sales in year 1 were 5.23.

Q: Assume that the year 2000 is used as the index base period and that sales were 12 million in the year 2000. If sales were 18 million in the year 2006, the simple index number for the year 2006 is: A) 1.5 B) 6 million C) 150 D) 0.666

Q: Which of the following time-series components is almost always present in sales data for electronics companies? A) Random B) Trend C) Seasonal D) All of the above

Q: Which of the following is true about index numbers? Index numbers are: A) used to measure the trend component. B) used to measure the seasonal component. C) used to measure the cyclical component. D) used to make a relative comparison of different time periods.

Q: Which of the following time-series components can be identified when a company has 12 weeks of data beginning January and extending through March? A) Seasonal component B) Random component C) Trend component D) Both B and C

Q: A company has a monthly time series that regularly shows sales being higher in the summer months. This is an example of which component? A) Trend B) Seasonal C) Cyclical D) Random

Q: A time-series plot that exhibits a general increase in value from the early periods to the latest time periods: A) most likely is exhibiting a cyclical component. B) has a trend component present in the data. C) will probably start to decline in a few periods. D) has a seasonal component present in the data

Q: The Cresswell Company updates its annual sales forecast every month as new sales data becomes available. The one-month update is called: A) the planning horizon. B) the forecast period. C) the forecast interval. D) the forecasting horizon.

Q: In a recent meeting, the sales manager for a drug company stated that she needed to have a forecast prepared for each week for the next six weeks. The week in this case is the: A) forecasting horizon. B) forecasting period. C) planning time. D) forecasting interval.

Q: In a recent meeting, the marketing manager for a large hardware company stated that he needed to have a forecast prepared for the next three months. The three-month period is called: A) the forecasting horizon. B) the forecasting period. C) the planning time. D) a business cycle.

Q: The process of selecting the forecasting technique to use in a particular application is called: A) model diagnosis. B) model specification. C) validity checking. D) model fitting.

Q: The Morgan Company is interested in developing a forecast for next month's sales. It has collected sales data for the past 12 months.Assuming that the company plans to use double exponential smoothing with starting values for the smoothed constant process value and smoothed trend value of 98.97 and 13.16 respectively, the MAD value for periods 2-12 is greater when alpha = 0.20 and beta = 0.20 than when alpha = 0.10 and beta = 0.10.

Q: Prior to conducting double exponential smoothing a simple linear regression is conducted and the trend equation is = 42 + 38.3t, so the smoothed constant process value should be C0= 38.3 and the smoothed trend value should be T0= 42.

Q: In a double smoothing model, large values for the two smoothing constants will result in greater smoothing of the time series.

Q: If you suspect that your time-series data has a strong downward trend, you should set the beta smoothing constant at value fairly close to negative 1.0

Q: If a time-series plot indicates that the data do not appear to exhibit a trend, then a double exponential smoothing model would likely be the most appropriate to use rather than simple exponential smoothing model.

Q: In a double smoothing model, the second smoothing constant is introduced to account for the trend in the data if one exists.