QUESTION: How are null values treated when one or more appears during the execution of a group function? [signinlocker] ANSWER: Null values in a column are ignored. [/signinlocker]
QUESTION: The city government has collected the following data on annual sales tax collections and new car registrations: Determine the following: (a) The least-squares regression equation. (b) Using the results of part (a), find the estimated sales tax collections if new car registrations total 22,000, (c) The coefficients of correlation and determination. [signinlocker] ANSWER: (a) …
The city government has collected the following data on annual sales tax Read More »
QUESTION: The following are two weekly forecasts made by two different methods for the number of gallons of gasoline, in thousands, demanded at a local gasoline station. Also shown are actual demand levels, in thousands of gallons: What are the MAD and MSE for each method? [signinlocker] ANSWER: Method 1: MAD: (0.20 …
Following are two weekly forecasts made by two different methods for the number Read More »
QUESTION: “Which forecasting technique can place the most emphasis on recent values? How does it do this?” [signinlocker] ANSWER: Exponential smoothing weighs all previous values with a set of weights that decline exponentially. It can place full weight on the most recent period (with an alpha of 1.0). This, in effect, is the naïve approach, …
QUESTION: A gas in a container had a measured pressure of 57 kPa. Calculate the pressure in units of atm and mmHg? [signinlocker] ANSWER: First, convert to atm (57 kPa = 57 x 103 Pa). 57 x 103 Pa x 1 atm/1.01325 x 105 Pa = 0.562 = 0.56 atm Next, convert to mmHg. 57 …
QUESTION: For each of the following statements, indicate whether it is true or false. If false, explain why it is false. In regression analysis: 1. The estimated coefficient of x1 can be positive in the bivariate model but negative in a multiple regression model. 2. When a model is refitted after y = income is …
QUESTION: For the World Data for Fertility and Literacy data file on the text CD, a MINITAB printout follows that shows fitting a multiple regression model for y = fertility, x1 = adult literacy rate (both sexes), x2 = combined educational enrollment (both sexes). Report the value of each of the following: (a) r between …
QUESTION: A logistic regression model describes how the probability of voting for the Republican candidate in a presidential election depends on x, the voter’s total family income (in thousands of dollars) in the previous year. The prediction equation for a particular sample is Find the estimated probability of voting for the Republican candidate when (a) …
QUESTION: Refer to the previous exercise. For what weight values do you estimate that a female crab has the probability (a) 0.50, (b) Greater than 0.50, and (c) less than 0.50, of having a male partner nesting nearby? [signinlocker] ANSWER: (a) x = – α̂ / ß = 3.695 / 1.815 = 2.04 (b) For …
QUESTION: For countries listed in the Twelve Countries data file on the text CD, y = Internet use (percent) is predicted by x1 = per capita GDP (gross domestic product, in thousands of dollars) with r2 = 0.88. Adding x2 = carbon dioxide emissions per capita to the model yields the results in the following …