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UCF QMB 3200 FINAL EXAM WITH COMPLETE 150
QUESTIONS AND CORRECT ANSWERS
QUESTION: A simple random sample of size n from an infinite population is a sample selected such that - ANSWER-each element is selected independently and is selected from the same population
QUESTION: The fact that the sampling distribution of sample means can be approximated by a normal probability distribution whenever the sample size becomes large is based on the - ANSWER-central limit theorem.
QUESTION: Cluster sampling is - ANSWER-a probability sampling method.
QUESTION: The central limit theorem states that - ANSWER-if the sample size n is large, then the sampling distribution of the sample mean can be approximated by a normal distribution.
Doubling the size of the sample will - ANSWER-reduce the standard error of the mean
QUESTION: The sample mean is the point estimator of - ANSWER-U
QUESTION: A simple random sample of size n from an infinite population of size N is to be selected. Each possible sample should have - ANSWER-the same probability of being selected
QUESTION: Which of the following statements regarding the sampling distribution of sample means is incorrect? - ANSWER-The standard deviation of the sampling distribution is the standard deviation of the population.
QUESTION: The value of the _____ is used to estimate the value of the population parameter - ANSWER- sample statistic
QUESTION: The sampling distribution of is the - ANSWER-probability distribution of all possible values of the sample proportion.
QUESTION: Which of the following is not a symbol for a parameter? - ANSWER-S.
QUESTION: The sample statistic characteristic s is the point estimator of - ANSWER-σ..
QUESTION: The distribution of values taken by a statistic in all possible samples of the same size from the same population is called a - ANSWER-sampling distribution.
QUESTION: Which of the following is a point estimator? - ANSWER-S.
QUESTION: As a rule of thumb, the sampling distribution of the sample proportion can be approximated by a normal probability distribution when - ANSWER-n(1 - p) ≥ 5 and np ≥ 5.
QUESTION: A sample of 92 observations is taken from an infinite population. The sampling distribution of is approximately - ANSWER-normal because of the central limit theorem.
QUESTION: The central limit theorem is important in Statistics because it enables reasonably accurate probabilities to be determined for events involving the sample average - ANSWER-when the sample size is large regardless of the distribution of the variable.
QUESTION: The distribution of values taken by a statistic in all possible samples of the same size from the same population is the sampling distribution of - ANSWER-The sample
QUESTION: Which of these best describes a sampling distribution of a statistic? - ANSWER-It is the distribution of all of the statistics calculated from all possible samples of the same sample size.
QUESTION: From a population that is normally distributed, a sample of 30 elements is selected and the standard deviation of the sample is computed. For the interval estimation of μ, the proper distribution to use is the - ANSWER-t distribution with 29 degrees of freedom.
QUESTION: As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution - ANSWER-becomes smaller.
QUESTION: The value added and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the - ANSWER-margin of error.
QUESTION: What is the symbol for the population mean? If the population follows a normal distribution, the confidence interval is _____ and can be used for any sample size. If the population does not follow a normal distribution, the confidence interval will be _____. Which of the following choices correctly complete this statement? - ANSWER-exact; approximate.
QUESTION: The t value for a 99% confidence interval estimation based upon a sample of size 10 is - ANSWER-3.250.
QUESTION: To compute the necessary sample size for an interval estimate of a population proportion, all of the following procedures are recommended when p is unknown except - ANSWER-using .95 as an estimate.
QUESTION: Using an α = .04, a confidence interval for a population proportion is determined to be .65 to .75. If the level of significance is decreased, the interval for the population proportion - ANSWER- becomes wider.
QUESTION: For a fixed confidence level and population standard deviation, if we would like to cut our margin of error to 1/3 of the original size, we should take a sample size that is - ANSWER-nine times as large as the original sample size.
QUESTION: The sampling distribution of can be approximated by a normal distribution as long as - ANSWER-np> 5 and n(1-p)>5 greater or equals.
QUESTION: When "s" is used to estimate "σ," the margin of error is computed by using the - ANSWER-t distribution.
QUESTION: The margin of error in an interval estimate of the population mean is a function of all of the following except the - ANSWER-sample mean.
QUESTION: For a fixed sample size, n, in order to have a higher degree of confidence, the margin of error and the width of the interval - ANSWER-must be larger.
QUESTION: The probability that the interval estimation procedure will generate an interval that does not contain μ is known as the - ANSWER-level of significance.
QUESTION: As the sample size increases, the margin of error - ANSWER-decreases.
QUESTION: When the level of confidence decreases, the margin of error - ANSWER-becomes smaller.
QUESTION: An approximate value of a population parameter that provides limits and believed to contain the value of the parameter is known as - ANSWER-the interval estimate.
QUESTION: To compute the necessary sample size for an interval estimate of a population mean, all of the following procedures are recommended when σ is unknown except - ANSWER-using σ = 1.
QUESTION: For the interval estimation of μ when σ is known and the sample is large, the proper distribution to use is - ANSWER-the normal distribution.
QUESTION: What is the symbol for the sample mean? - ANSWER-X bar
QUESTION: The p-value is a probability that measures the support (or lack of support) for the - ANSWER- null hypothesis.
QUESTION: As the test statistic becomes larger, the p-value - ANSWER-becomes smaller.
QUESTION: A news reporter states that the average number of temperature in January has never dropped below 10 degrees Fahrenheit. You go online to research this claim. The appropriate hypotheses are - ANSWER-H0: u>10, Ha: u<10.
QUESTION: The probability of making a Type I error when the null hypothesis is true as an equality is called the - ANSWER-level of significance.
QUESTION: Which of the following null hypotheses cannot be correct? - ANSWER-H0: u not=10.
QUESTION: It has been stated that at least 75 out of every 100 people who go to the movies on Saturday night buy popcorn. Identify the null and alternative hypotheses. - ANSWER-H0: p>.75, Ha: p<.75.
QUESTION: A fast food restaurant has automatic drink dispensers to help fill orders more quickly. When the 12 ounce button is pressed, they would like for exactly 12 ounces of beverage to be dispensed. There is, however, undoubtedly some variation in this amount. The company does not want the machine to systematically over fill or under fill the cups. Which of the following gives the correct set of hypotheses? - ANSWER-H0: u=12, Ha: u not=
QUESTION: Which of the following describes a Type II Error? - ANSWER-Accept H0 when H0 is false.
QUESTION: Which of the following does not need to be known in order to compute the p-value? - ANSWER-The level of significance.
QUESTION: What is the probability of making a Type I error? - ANSWER-𝛼 alpha.
QUESTION: The p-value - ANSWER-must be a number between 0 and 1.
QUESTION: The normal probability distribution can be used to approximate the sampling distribution of as long as - ANSWER-np>5 and n(1-p)>5.
QUESTION: For the case where σ is unknown, which statistic is used to estimate σ? - ANSWER-S
QUESTION: For the case where σ is unknown, the test statistic has a t distribution. How many degrees of freedom does it have? n-1Which of the following describes a Type I Error? - ANSWER-Reject H0 when H is true.
QUESTION: The matched sample design often leads to a smaller sampling error than the independent sample design. The primary reason is that in a matched sample design - ANSWER-variation between subjects is eliminated because the same subjects are used for both treatments.
QUESTION: Suppose we are constructing an interval estimate for the difference between the means of two populations when the standard deviations of the two populations are unknown. Suppose it can be assumed that the two populations have equal variances. If n1 is the size of sample 1 and n2 is the size of sample 2, we must use a t distribution with - ANSWER-degrees of freedom.
QUESTION: A researcher recruits 25 people to participate in a study on alcohol consumption and its interactions with Tylenol. The 25 participants had to come to a check-in center every day at 7:00 a.m. for one week. They were given various amounts of alcohol. Each day, each participant would flip a coin to determine if they also took Tylenol with their alcohol. They found that their BAC was 25% higher on days when they were given Tylenol with their alcohol than when they drank alcohol alone. This is an example of a(n) - ANSWER-matched sample design.
QUESTION: The standard error of is given by - ANSWER-The one that has a root square covering the entire thing
communities and buy a real Christmas tree, and let P2 = the proportion of all people who live in urban communities and buy a real Christmas tree. State the null and alternative hypotheses. - ANSWER-H0: p1- p2<0, Ha:p1-p2>
QUESTION: The sampling distribution of P1-P2 is approximated by a normal distribution when - ANSWER-N1P1,N1(1-P1), N2P2, and N2(1-P2) are all greater than or equal to 5.
QUESTION: When completing a two-tailed hypothesis test about the difference between two population means, - ANSWER-the p-value must be doubled.
QUESTION: If two large independent random samples are taken from two populations, the sampling distribution of the difference between the two sample means - ANSWER-can be approximated by a normal distribution.
QUESTION: Regarding hypothesis tests about , the pooled estimate of P is a - ANSWER-weighted average of P1 and P2.
QUESTION: When x is unknown, which of the following is used to estimate x? s Suppose we have a t distribution based upon two sample means with unknown population standard deviations, which we are unwilling to assume are equal. When we calculate the appropriate degrees of freedom, we should - ANSWER-round the calculated degrees of freedom down to the nearest integer.
QUESTION: If we are interested in testing whether the proportion of items in population 1 is larger than the proportion of items in population 2, then the - ANSWER-alternative hypothesis should state.
QUESTION: In regression analysis, the equation in the form y = 𝛽0 + 𝛽1x + ε is called the - ANSWER- Regression model.
QUESTION: The model developed from sample data that has the form y^hat=bo+b1x is known as the - ANSWER-regression equation.
QUESTION: The tests of significance in regression analysis are based on several assumptions about the error term ɛ. Additionally, we make an assumption about the form of the relationship between x and y. We assume that the relationship between x and y is - ANSWER-Linear.
QUESTION: If a residual plot of x versus the residuals, y - ŷ, shows a non-linear pattern, then we should conclude that - ANSWER-the regression model is not an adequate representation of the relationship between the variables.
QUESTION: When working with regression analysis, an outlier is - ANSWER-any observation that does not fit the trend shown by the remaining data.
QUESTION: Observations with extreme values for the independent variables are called - ANSWER-high leverage points.
QUESTION: The difference between the observed value of the dependent variable and the value predicted using the estimated regression equation is called a(n) - ANSWER-residual.
QUESTION: If the coefficient of determination is a positive value, then the coefficient of correlation - ANSWER-Can be either negative or positive
QUESTION: The tests of significance in regression analysis are based on assumptions about the error term ɛ. One such assumption is that the error term ɛ is a random variable with a mean or expected value of - ANSWER-0.
QUESTION: When studying the relationship between two quantitative variables, whenever we want to predict an individual value of y for a new observation corresponding to a given value of x, we should use a(n) - ANSWER-Prediction interval.
QUESTION: Graphical representation of the residuals that can be used to determine whether the assumptions made about the regression model appear to be valid is called a - ANSWER-Residual plot.
QUESTION: The mathematical equation relating the independent variable to the expected value of the dependent variable, E(y)=B0+b1x, is known as the - ANSWER-regression equation.
QUESTION: When constructing a confidence or a prediction interval to quantify the relationship between two quantitative variables, the appropriate degrees of freedom are - ANSWER-n-2.
QUESTION: Influential observations always - ANSWER-None of the above are correct
QUESTION: In a regression analysis, an outlier will always increase - ANSWER-The value of the correlation.
QUESTION: The tests of significance in regression analysis are based on assumptions about the error term ɛ. One such assumption is that the error term follows ɛ a(n) _____ distribution for all values of x. - ANSWER-Normal.
QUESTION: In regression analysis, the variable that is being predicted is the - ANSWER-dependent variable.
QUESTION: An F test, based on the F probability distribution, can be used to test for - ANSWER- Significance in regression.
QUESTION: Which of the following statements is false? - ANSWER-Regression analysis can be interpreted as aprocedure for establishing a cause-and-effect relationship between variables.
QUESTION: A graph of the standardized residuals plotted against values of the normal scores that helps to determine whether the assumption that the error term has a normal probability distribution appears to be valid is called a - ANSWER-Normal probability plot
QUESTION: When studying the relationship between two quantitative variables, an interval estimate of the mean value of y for a given value of x is called a(n) - ANSWER-confidence interval.
QUESTION: The value of the coefficient of correlation (r) - ANSWER-can be equal to the value of the coefficient of determination (r2).
QUESTION: When we conduct significance tests for a multiple regression relationship, the F test will be used as the test for - ANSWER-Overall significance
QUESTION: In multiple regression analysis, any observation with a standardized residual of less than _____ or greater than _____ is known as an outlier. - ANSWER--2;2.
QUESTION: In a multiple regression model, the variance of the error term, ε, is assumed to be - ANSWER-the same for all values of x1, x2,..., xp..
QUESTION: All things held constant, which interval will be wider: a confidence interval or a prediction interval? - ANSWER-Prediction interval
QUESTION: Since the multiple regression equation generates a plane or surface, its graph is called a - ANSWER-Response surface
QUESTION: When we use the estimated regression equation to develop an interval that can be used to predict the mean for ALL units that meet a particular set of given criteria, that interval is called a(n) - ANSWER-confidence interval.
QUESTION: The term used to describe the case when the independent variables in a multiple regression model are correlated is - ANSWER-multicollinearity.
QUESTION: A variable used to model the effect of categorical independent variables is called a(n) - ANSWER-Dummy Variable
QUESTION: In a multiple regression model, the values of the error term, ε, are assumed to be - ANSWER- Independent of each other
QUESTION: The method used to develop the estimated regression equation that minimizes the sum of squared residuals is called the - ANSWER-least squares method.
QUESTION: The mathematical equation that explains how the dependent variable y is related to several independent variables and has the form y=B0+b1x1+b2x2+....Bpxp+e is called - ANSWER-A multiple regression model.
QUESTION: When we conduct significance tests for a multiple regression relationship, the t test can be conducted for each of the independent variables in the model. Each of those tests are called tests for - ANSWER-Individual significance.
QUESTION: In a multiple regression model, the error term ε is assumed to have a mean of - ANSWER-
QUESTION: In general, R2 always _____ as independent variables are added to the regression model. - ANSWER-Increases.
QUESTION: The multiple regression equation based on the sample data, which has the form of y^ hat= b0+b1x1+b2x2+....+bpxp, is called - ANSWER-An estimated multiple regression equation.
QUESTION: Looking at the sample correlation coefficients between the response variable and each of the independent variables can give us a quick indication of which independent variables are, by themselves, - ANSWER-Good predictors.
QUESTION: When carrying out an F test to determine if the addition of extra predictor variables results in a significant reduction in the error sum of squares, what are the degrees of freedom of the numerator and denominator of the F statistic? - ANSWER-The numerator degrees of freedom equals the number of predictors added to the model. The denominator degrees of freedom is n—p—1.
QUESTION: The regression model y=B0+B1x1+B2x2+B3x2^2+B4x2^2+B5x1x2+e is a - ANSWER-second- order model with two predictor variables.
QUESTION: What test can be used to determine whether first-order autocorrelation is present? - ANSWER-Durbin-Watson test
QUESTION: With negative autocorrelation, we expect a positive residual in one period to be followed by
- ANSWER-a negative residual in the next period, then a positive residual, and so on.
QUESTION: When autocorrelation is present, which of the following assumptions is violated? - ANSWER- The error terms are independent.
QUESTION: Which of the following is not an iterative variable selection procedure? - ANSWER-Best- subsets regression
QUESTION: Multicollinearity can cause problems if the absolute value of the sample correlation coefficient exceeds - ANSWER-0.7 for any two of the independent variables
QUESTION: The variable selection procedure that identifies the best regression equation, given a specified number of independent variables, is - ANSWER-Best-subsets regression.
QUESTION: The regression model y=B0+B1x1+B2x1^2+e is a - ANSWER-Second-order model with one predictor variable.
QUESTION: In order to use the output from a multiple regression model to perform the ANOVA test on the difference among the means of four populations, how many dummy variables do we need to use to indicate treatments? - ANSWER-Three
QUESTION: When dealing with the problem of nonconstant variance, we can apply the reciprocal transformation, which means that we use - ANSWER-1/y as the dependent variable instead of y.
QUESTION: A model in the form of , where each independent variable zj (for j = 1, 2,..., p) is a function of x1, x2,..., xk, is known as the: - ANSWER-general linear model.
QUESTION: If the value of y in time period t is related to its value in time period t - 1, we say that - ANSWER-first-order autocorrelation is present.
QUESTION: The effect of two independent variables acting together is called - ANSWER-Interaction.
QUESTION: Which of the following options guarantees that the best model for a given number of variables will be found? - ANSWER-Best-subsets regression
QUESTION: How many independent variables does the forward selection process start with? - ANSWER- Zero
QUESTION: Which of the following statements about the backward elimination procedure is false? - ANSWER-It begins with zero independent variables.
QUESTION: When determining the best estimated regression equation to model a set of data, the procedure that allows an independent variable to enter the model at one step, be removed at a subsequent step, and then enter the model at a later step is - ANSWER-stepwise regression.
QUESTION: The parameters of nonlinear models have exponents - ANSWER-other than one.
QUESTION: In multiple regression analysis, the general linear model: - ANSWER-can be used to accommodate curvilinear relationships between the independent variables and the dependent variable.
QUESTION: Suppose sales data for the first quarter had a seasonal index of .80. Which of the following statements correctly interprets this figure? - ANSWER-The sales average is 20% below the trend estimate.
QUESTION: The time series model that is appropriate in situations where the seasonal fluctuations do not depend upon the level of the time series is - ANSWER-Additive model.
QUESTION: The average of the sum of squared forecast errors is called - ANSWER-mean squared error.
QUESTION: A forecast model of the form is called a(n) - ANSWER-Quadratic trend equation.
QUESTION: What is the component of a time series model that is attributable to multiyear cycles in the time series? - ANSWER-The cyclical component
QUESTION: The average of all the historical data will always provide the best results as long as the underlying time series is - ANSWER-Stationary
QUESTION: Seasonal and irregular components with values greater than 1.00 indicate effects _____ the trend estimate and values below 1.00 indicate effects _____ the trend estimate. Which two words correctly complete this sentence? - ANSWER-Above; below
QUESTION: What kind of model is appropriate if the seasonal fluctuations change over time, growing larger as the dependent variable increases because of a long-term linear trend? - ANSWER-A multiplicative model
QUESTION: A positive forecast error indicates that the forecasting method _____ the dependent variable. - ANSWER-Underestimated.
