Supermarket Checkout Lines. Retail chain Kroger has more than 2700 locations and is the largest supermarket in the United States based on revenue. Kroger has invested heavily in data, technology, and analytics. Feeding predictive models with data from an infrared sensor system called QueVision to anticipate when shoppers will reach the checkout counters, Kroger is able to alert workers to open more checkout lines as needed. This has allowed Kroger to lower its average checkout time from four minutes to less than 30 seconds (Retail Touchpoints).
Consider the data in the file Checkout. The file contains 32 observations. Each observation gives the arrival time (measured in minutes before 6 P.M.) and the shopping time (measured in minutes).
- a. Develop a
scatter diagram for arrival time as the independent variable. - b. What does the scatter diagram developed in part (a) indicate about the relationship between the two variables? Do there appear to be any outliers or influential observations? Explain.
- c. Using the entire data set, develop the estimated regression equation that can be used to predict the shopping time given the arrival time.
- d. Use residual analysis to determine whether any outliers or influential observations are present.
After looking at the scatter diagram in part (a), suppose you were able to visually identify what appears to be an influential observation. Drop this observation from the data set and fit an estimated regression equation to the remaining data. Compare the estimated slope for the new estimated regression equation to the estimated slope obtained in part (c). Does this approach confirm the conclusion you reached in part (d)? Explain.
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Chapter 14 Solutions
Essentials Of Statistics For Business & Economics
- Lovely Lawns, Inc., intends to use sales of lawn fertilizer to predict lawn mower sales. The store manager estimates a probable six- week lag between fertilizer sales and mower sales. The pertinent data are: Fertilizer Number of Fertilizer Number of Sales Mowers Sold Sales Mowers Sold Period (tons) (six-week lag) Period (tons) (six-week lag) 1 1.6 10 8. 1.3 7 1.3 8 1.7 10 3 1.8 11 10 1.2 6. 4 2.0 12 1.9 11 2.2 12 12 1.4 1.6 9. 13 1.7 10 7 1.5 14 1.6 a. Determine the correlation between the two variables. Does it appear that a relationship exists between these variables will yield good predictions? (Do not round intermediate calculations and round your answer to 3 decimal places.) it appears that a positive v relationship exists between these variables. b. Obtain a linear regression line for the data. (Negative values should be indicated by a minus sign. Do not round intermediate calculations and round your answers to 3 decimal places.) Y = O Xi + c. Predict expected lawn mower sales…arrow_forwardCompare the primary types of forecasting methods used to determine demand.arrow_forwardPart 2: The owner of a pet store is trying to decide whether to discontinue selling specialty clothes for pets. She suspects that only 4% of the customers buy specialty clothes for their pets and thinks that she might be able to replace the clothes with more interesting and profitable items on the shelves. Before making a final decision she decides to keep track of the total number of customers for a day, and whether they purchase specialty clothes for their pet. Assuming the pet store owner is correct in thinking that only 4% of her customers purchase specialty clothes for their pets, how many customers should she expect before someone buys a garment for their pet? l. 2. What is the probability that she does not sell a gament until the 7th customer? Show work. What is the probability that exactly 3 of the first 10 customers buy specialty clothes for their pet? Show work. 4. What is the probability that at least 3 of the first 40 customers buy specialty clothes for their pet? Show…arrow_forward
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- Is a linear model appropriate for this type of data? Explain.arrow_forwardLarge companies typically collect volumes of data before designing a product, not only to gain information as to whether the product should be released, but also to pinpoint which markets would be the best targets for the product. Several months ago, I was interviewed by such a company while shopping at a mall. I was asked about my exercise habits and whether or not I'd be interested in buying a video/DVD designed to teach stretching exercises. I fall into the male, 18 35-years-old category, and I guessed that, like me, many males in that category would not be interested in a stretching video. My friend Jenny falls in the female, older-than-35 category, and I was thinking that she might like the stretching video. After being interviewed, I looked at the interviewer's results. Of the 97 people in my market category who had been interviewed, 12 said they would buy the product, and of the 116 people in Jenny's market category, 31 said they would buy it. Assuming that these data eame from…arrow_forwardThere are two major bookstores in a relatively large city. They constantly measure their performance relative to one another. The monthly sales receipts total $25,000 on average for Bookstore 1. Bookstore 2 is interested in knowing whether they have higher sales than their competition. The last 6 months of data from Bookstore 2 are given below. Month 1 2 3 4 5 6 Bookstore 2 $21,000 $12,000 $30,000 $17,000 $19,000 $30,000 a) Conduct an appropriate hypothesis test. Use the p-value method. b) Explain what a Type I Error would mean in this context (maximum 2 sentences). c) Explain what a Type II Error would mean in this context (maximum 2 sentences).arrow_forward
- Concur Technologies, Inc., is a large expense-management company located in Redmond, Washington. The Wall Street Journal asked Concur to examine the data from 8.3 million expense reports to provide insights regarding business travel expenses. Their analysis of the data showed that New York was the most expensive city, with an average daily hotel room rate of $198 and an average amount spent on entertainment, including group meals and tickets for shows, sports, and other events, of $172. In comparison, the U.S. averages for these two categories were $89 for the room rate and $99 for entertainment. The table in the Excel Online file below shows the average daily hotel room rate and the amount spent on entertainment for a random sample of 9 of the 25 most visited U.S. cities (The Wall Street Journal, August 18, 2011). Construct a spreadsheet to answer the following questions. City Hotel Room Rate ($) Entertainment ($) Boston 145 163 Denver 97 105 Nashville 93 101 New Orleans…arrow_forwardAztec Industries has developed a forecasting model that was used to forecast during a 10-month period. The forecasts and actual demand were as follows: Measure the accuracy of the forecast by using MAD, MAPD, and cumulative error. Does the forecast method appear to be accurate?arrow_forwardBriefly explain how the organization forecast sales for its products.a. Using historical sales data, choose a quantitative technique to forecast sales for thatorganisation for the next sales period. Comment on the appropriateness of thetechnique used.b. Describe three strategies that the organization uses to compete and comment on theappropriateness of these strategiesarrow_forward
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