Exam 4: Correlation and Linear Regression

A small independent organic food store offers a variety of specialty coffees.To determine whether price has an impact on sales, the managers kept track of how many pounds of each variety of coffee were sold last month. Based on the data and summary statistics shown below, the slope of the estimated regression line that relates the response variable (monthly sales) to the predictor variable (price per pound) is ________________________ .

A supermarket chain gathers data on the amount they spend on promotional material (e.g., coupons, etc.) and sales revenue generated each quarter.The predictor variable is ________________________ .

A company studying the productivity of its employees on a new information system was interested in determining if the age (X) of data entry operators influenced the number of completed entries made per hour (Y).The regression equation is )Suppose the actual completed entries per hour for an operator who is 35 years old was 8.The residual is _______ .

A small independent organic food store offers a variety of specialty coffees.To determine whether price has an impact on sales, the managers kept track of how many pounds of each variety of coffee were sold last month.Based on the scatterplot shown below, which of the following statements is true?

The scatterplot shows monthly sales figures (in units) and number of months of experience for a sample of salespeople. The association between monthly sales and level of experience can be described as ________________________ .

Data were collected on monthly sales revenues (in $1,000s) and monthly advertising expenditures ($100s) for a sample of drug stores.The regression line relating revenues (Y) to advertising expenditure (X) is estimated to be )The correct interpretation of the slope is that for each additional ____________________________ .

Based on the following residual plot, which condition / assumption for linear regression is not satisfied? Border line missing for graph

A small independent organic food store offers a variety of specialty coffees.To determine whether price has an impact on sales, the managers kept track of how many pounds of each variety of coffee were sold last month. Based on the scatterplot, the linear relationship between number of pounds of coffee sold per week and price is ________________________ .

The scatterplot shows monthly sales figures (in units) and number of months of experience for a sample of salespeople. The correlation between monthly sales and level of experience is most ________________________ .

A small independent organic food store offers a variety of specialty coffees.To determine whether price has an impact on sales, the managers kept track of how many pounds of each variety of coffee were sold last month. Based on the data and summary statistics, the intercept of the estimated regression line that relates the response variable (monthly sales) to the predictor variable (price per pound) is ______________ .

A study examined consumption levels of oil and carbon dioxide emissions for sample of counties.The response variable in this study is ________________________ .

For the following scatterplot, The likely correlation coefficient is ________________________ .

A company studying the productivity of their employees on a new information system was interested in determining if the age (X) of data entry operators influenced the number of completed entries made per hour (Y).The regression equation is )If s_x=14.04 and s_y=2.61, then the correlation coefficient between age and productivity is ____ .

Suppose the correlation, r, between two variables x and y is -0.44.What percentage of the variability in y cannot be explained by x?

A small independent organic food store offers a variety of specialty coffees.To determine whether price has an impact on sales, the managers kept track of how many pounds of each variety of coffee were sold last month. Based on the summary statistics shown below, what percent of the variability in the number of pounds of coffee sold per week can be explained by price?

Shown below is a correlation table showing correlation coefficients between stock price, earnings per share (EPS) and price/earnings (P/E) ratio for a sample of 19 publicly traded companies.Which of the following statements is false? Correlations: Stock Price, EPS, PE

Data were collected on monthly sales revenues (in $1,000s) and monthly advertising expenditures ($100s) for a sample of drug stores.The regression line relating revenues (Y) to advertising expenditure (X) is estimated to be )The predicted sales revenue for a month in which $1,000 was spent on advertising is ______________ .

The disadvantage of re-expressing variables is that ________________________ .

Suppose the correlation, r, between two variables x and y is -0.44.What would you predict about a y value if the x value is 2 standard deviations above its mean?

Linear regression was used to describe the trend in world population over time.Below is a plot of the residuals versus predicted values.What does the plot of residuals suggest?