QBA Exam 2

One reason a sample may fail to represent the population of interest is _____. a. population proportion b. measurement error c. statistical inference d. sampling error

d. sampling error

Forecast error _____.

a. is associated with measuring forecast accuracy

The process of making a conjecture about the value of a population parameter, collecting sample data that can be used to assess this conjecture, measuring the strength of the evidence against the conjecture that is provided by the sample, and using these results to draw a conclusion about the conjecture is known as _____.

b. hypothesis testing

In a linear regression model, the variable (or variables) used for predicting or explaining values of the response variable are known as the _____. It(they) is(are) denoted by x.

b. independent variable

The degree of correlation among independent variables in a regression model is called _____.

b. multicollinearity

A _____ is used to visualize sample data graphically and to draw preliminary conclusions about the possible relationship between the variables.

b. scatter chart

What would be the coefficient of determination if the total sum of squares (SST) is 23.29 and the sum of squares due to regression (SSR) is 10.03?

c. 0.43

If the forecasted value of the time series variable for period 2 is 22.5 and the actual value observed for period 2 is 25, what is the forecast error in period 2?

2.5

The population parameters that describe the y-intercept and slope of the line relating y and x, respectively, are _____.

a. B0 and B1

Which statement is NOT true? a. Failing to reject the null hypothesis when it is false is a Type I error. b. The probability of making a Type I error is symbolized by α. c. Type II error can occur for both one and two-tailed tests. d. Rejecting the null hypothesis when it is true is a Type I error.

a. Failing to reject the null hypothesis when it is false is a Type I error.

A pizza shop advertises that they deliver in 30 minutes or less or it is free. People who live in homes that are located on the opposite side of town believe it will take the pizza shop longer than 30 minutes to make and deliver the pizza. Write the null and alternative hypotheses that can be used to conduct a significance test.

a. H0: u ≤ 30, Ha: u > 30

What are the two decisions that you can make from performing a hypothesis test?

a. Reject the null hypothesis; Fail to reject the null hypothesis

A variable used to model the effect of categorical independent variables in a regression model which generally takes only the value zero or one is called _____.

a. a dummy variable

The moving averages and exponential smoothing methods are appropriate for a time series exhibiting _____.

a. a horizontal pattern

A variable used to model the effect of categorical independent variables in a regression model is known as a _____.

a. dummy variable

Two approaches to drawing a conclusion in a hypothesis test are _____.

a. p-value and critical value

A forecast is defined as a(n) _____.

a. prediction of future values of a time series

A procedure for using sample data to find the estimated regression equation is _____.

a. the least squares method

Trend refers to _____.

a. the long-run shift or movement in the time series observable over several periods of time

An exponential trend pattern occurs when _____.

a. the percentage change between periods in the value of the variable is relatively constant

If a time series plot exhibits a horizontal pattern, then _____.

a. there is still not enough evidence to conclude that the time series is stationary

A positive forecast error indicates that the forecasting method _____ the dependent variable.

a. underestimated

_____ is used to test the hypothesis that the values of the regression parameters ß1, ß2, ... ßq are all zero.

b. An F test

The average number of hours for a random sample of mail order pharmacists from company A was 50.1 hours last year. It is believed that changes to medical insurance have led to a reduction in the average work week. To test the validity of this belief, the hypotheses are _____.

b. H0: u ≥ 50.1, Ha: u < 50.1

_____ refers to the use of sample data to calculate a range of values that is believed to include the value of the population parameter.

b. Interval estimation

Which statement is NOT true? a. The greater the level of confidence, the larger the z-score. b. Rejecting the null hypothesis when it is true is a Type II error. c. The greater the level of confidence, the wider the confidence interval. d. The greater the level of confidence, the more likely it is that the confidence interval actually includes the true population mean.

b. Rejecting the null hypothesis when it is true is a Type II error.

Determine whether the alternative hypothesis is left-tailed, right-tailed, or two-tailed: H0: μ = 11, Ha: μ > 11.

b. Right-tailed

A time series plot of a period of time (in weeks) versus sales (in 1,000's of gallons) is shown below. Which of the following data patterns best describes the scenario shown?

b. Time series with a horizontal pattern

Which of the following statements is the objective of the moving averages and exponential smoothing methods?

b. To smooth out random fluctuations in the time series

Which of the following states the objective of time series analysis?

b. To uncover a pattern in a time series and then extrapolate the pattern into the future

A normally distributed error term with a mean of zero would _____.

b. allow more accurate modeling

With reference to time series data patterns, a cyclical pattern is the component of the time series that _____.

b. shows a periodic pattern lasting more than one year

In the graph of the simple linear regression equation, the parameter ß1 is the _____ of the true regression line.

b. slope

The process of making estimates and drawing conclusions about one or more characteristics of a population through analysis of sample data drawn from the population is known as _____.

b. statistical inference

The graph of the simple linear regression equation is a(n) _____

b. straight line

The _____ is a measure of the error that results from using the estimated regression equation to predict the values of the dependent variable in the sample.

b. sum of squares due to error (SSE)

The moving averages method refers to a forecasting method that _____.

b. uses the average of the most recent data values in the time series as the forecast for the next period

A student wants to determine if pennies are really fair when flipped, meaning equally likely to land heads up or tails up. He flips a random sample of 50 pennies and finds that 28 of them land heads up. If p denotes the true probability of a penny landing heads up when flipped, what are the appropriate null and alternative hypotheses?

c. H0: p = 0.5, Ha: p ≠ 0.5.

The owners of a fast food restaurant have 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, 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?

c. H0: u = 12, Ha: u ≠ 12

_____ refers to the degree of correlation among independent variables in a regression model.

c. Multicollinearity

Which of the following is not present in a time series?

c. Operational variations

_____ is a statistical procedure used to develop an equation showing how two variables are related.

c. Regression analysis

A regression analysis involving one independent variable and one dependent variable is referred to as a _____.

c. Simple linear regression

Which of the following relationships would have a negative correlation coefficient? a. Cost of a car and the amount of tax to be paid b. The square footage of a home and the price of the home c. Supply and demand d. Amount of a bill at a restaurant and the amount of the tip

c. Supply and demand

A Type I error is committed when _____.

c. a true null hypothesis is rejected

In the simple linear regression model, the _____ accounts for the variability in the dependent variable that cannot be explained by the linear relationship between the variables.

c. error term

The coefficient of determination _____.

c. is used to evaluate the goodness of fit

A null and alternative hypothesis for a one proportion z test are given as H0: p ≥ 0.8, Ha: p < 0.8. This hypothesis test is _____

c. lower-tailed

Regression analysis involving one dependent variable and more than one independent variable is known as _____.

c. multiple regression

In a simple linear regression analysis the quantity that gives the amount by which the dependent variable changes for a unit change in the independent variable is called the _____.

c. slope of the regression line

__________ is the amount by which the predicted value differs from the observed value of the time series variable.

d. Forecast error

In a linear regression model, the variable that is being predicted or explained is known as _____. It is denoted by y and is often referred to as the response variable.

d. dependent variable

In the moving averages method, the order k determines the _____.

d. number of time series values under consideration

A time series that shows a recurring pattern over one year or less is said to follow a _____.

d. seasonal pattern

In a simple linear regression model, y = ß0 + ß1x + ε the parameter ß1 represents the _____.

d. slope of the true regression line

Using a large value for order k in the moving averages method is effective in _____.

d. smoothing out random fluctuations

In the graph of the simple linear regression equation, the parameter ß0 represents the _____ of the true regression line.

d. y-intercept