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An Internet-based or emailed survey is not an alternative method of data collection. When estimating sample size, a 90 percent confidence level will result in a smaller sample size than a 95 percent confidence level. Answer: TRUE A business with […]

Aceco has a contract with a supplier to ship parts that contain no more than three percent defects. When a large shipment of parts comes in, Aceco samples n = 150. Based on the results of the sample, they either […]

When determining the sample size for a proportion, if you have no previous information available to estimate p, then the best value to use is π = 0.5. When testing whether two paired populations have equal medians and the sample […]

The only two types of random variables are discrete and continuous random variables. A 95 percent confidence interval for a mean will contain 95 percent of the population within the interval. Answer: FALSE Sawyer & Company is a law firm […]

To test for the stopping distances of four brake systems, 10 of the same make and model of car are selected randomly and then are assigned randomly to each of four brake systems. This is a randomized complete block design. […]

Lube-Tech is a major chain whose primary business is performing lube and oil changes for passenger vehicles. The national operations manager has stated in an industry newsletter that the mean number of miles between oil changes for all passenger cars […]

Managers for a company that produces a weight loss product claim that the median weight lost over six weeks for people who use this product will be at least 20 pounds. The following data were collected from a sample of […]

The Morgan Company is interested in developing a forecast for next month’s sales. It has collected sales data for the past 12 months. After analyzing these data, if the company wishes to use double exponential smoothing with alpha = 0.20 […]

If a population is skewed, the point estimate will be pushed to the right or left of the middle of the confidence interval estimate. The Nationwide Motel Company has determined that 70 percent of all calls for motel reservations request […]

Two common unweighted indexes are the Paasche Index and the Laspeyres Index. 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 […]

In a Mann-Whitney U test, if the sample sizes are large then the test statistic can be approximated by the student’s t-distribution. The primary application for the hypergeometric probability distribution is in situations where the sampling is done without replacement […]

In a large sample test about a single population median, it is appropriate to employ the standard normal distribution so long as the population is also normally distributed. A bank is interested in determining whether its customers’ checking balances are […]

In constructing a stem and leaf diagram, there is a hard-and-fast rule for defining the stem and the leaves. In order to test the difference in populations means, samples were collected for two independent populations where the variances are assumed […]

A large sample Mann-Whitney U test should be used when the sample sizes exceed 20. In conducting the Wilcoxon Matched-Pairs Signed Rank test, the difference between each pair of values must be found prior to conducting any ranking. Answer: TRUE […]

The three components of the regression model-building process are model specification, model fitting, and model diagnosis. A major airline has stated in an industry report that its mean onground time between domestic flights is less than 18 minutes. To test […]

In a situation where we know the population standard deviation but wish to estimate the population mean using a 90 percent confidence interval, the critical value is z = 1.645. A major manufacturer of home electronics is interested in determining […]

A report in a consumer magazine indicated that with 90 percent confidence, the mean number of hours that a particular brand light bulb lasts is between 900 and 1,100 hours. Based on this, the sample mean that produced this estimate […]

Standard stepwise regression is a good way of identifying potential multicollinearity problems since we are able to see the impact on the model at each step that occurs when a new variable is added to the model. For instance, if […]

The Brockingham Carpet Company prides itself on high quality carpets. At the end of each day, the company quality managers select 3 square yards for inspection. The quality standard requires an average of no more than 2.3 defects per square […]

One of the variables that are being considered for inclusion in a multiple regression model is marital status of the customer. There are four possible responses listed for this variable. Based on this, four dummy variables will need to be […]

If a set of data has 540 values, the 3rd quartile corresponds to approximately the 135th value when the data have been arranged in numerical order. In estimating a population mean, a large sample size is generally preferable to a […]

In most processes, the process control limits are set to correspond with the specification limits on the product. Six food critics each visited and rated four different restaurants. Each critic visited each restaurant on three separate occasions and recorded a […]

In a multiple regression model, R-square can be computed by squaring the highest correlation coefficient between the dependent variable and any independent variable. Answer: FALSE The distribution for the number of emergency calls to a city’s 911 emergency number in […]

An assembly process takes between 20 and 40 minutes to complete with the distribution of time thought to be uniformly distributed. Based on this, the percentage of assemblies that require less than 25 minutes is 0.05. Answer: FALSE Because variations […]

Cross County Bicycles makes two mountain bike models that each come in three colors. The following table shows the production volumes for last week: What is the joint probability that a product manufactured is a YZ-99 and brown? A) 0.2088 […]

Students who have completed a speed reading course have reading speeds that are normally distributed with a mean of 950 words per minute and a standard deviation equal to 220 words per minute. If two students were selected at random, […]

An issue that faces individuals investing for retirement is allocating assets among different investment choices. Suppose a study conducted 10 years ago showed that 65% of investors preferred stocks to real estate as an investment. In a recent random sample […]

Taking a larger sample size will always result in less sampling error but costs more money and takes more time. Answer: FALSE If a sample is selected using random sampling methods, the primary reason that the sample mean might be […]

In situations involving two or more variables, both histograms and bar charts can be used for multiple variables on the same graph. Answer: FALSE The variance inflation factor (VIF) provides a measure for each independent variable of how much multicollinearity […]

The population mean of income for adults in a particular community is known to be $28,600. Given this information, the sampling distribution of values will be less than this depending on the size of the sample used in developing the […]

If a simple least squares regression model is developed based on a sample where the two variables are known to be positively correlated, the sum of the residuals will be positive. One of the assumptions of the Mann-Whitney U test […]

The Baker Oil and Gas Company has four retail locations, code-named A, B, C, and D. The following table illustrates the percentage of total company sales at each store and also the percentage of customers at that store who make […]

In a two-tailed hypothesis test the area in each tail of the rejection region is equal to α. Answer: FALSE If the observed value in a time series for period 3 is yt = 128, and the seasonal index that […]

Analysis of variance can only be done for fixed effects. A pie chart is almost always constructed when the variable of interest is qualitative. Answer: FALSE The forecasting interval is the unit of time for which forecasts are made. Answer: […]

In a multiple regression analysis with three independent variables the null hypothesis for conducting the test of the overall model is: H0: β0= β1= β2= β3= 0. Answer: FALSE In a time series with quarterly sales data, assume that the […]