Statistics
posted by Willie Brown .
The assignment is in three parts:
1. An analytic section that you will submit as an Excel spread sheet
2. A PowerPoint presentation of 3 to 5 slides.
3. A narrative section that you will submit as a two to three page Word document
First, read the business case and identify the business decisions that need to be made. Then, using the case datasheet, perform a statistical analysis of the data and obtain the required statistics. Submit your analysis as an Excel spreadsheet. Your spreadsheet will contain numerical data. You will then submit a PowerPoint file to showcase graphical information. Finally, in a narrative of about two to three pages, describe the business situation and the decisions that the business must make. Explain, based on your findings, a recommended course of action for the business. Refer to the statistics you calculated and the graphs you created in the spreadsheet. Submit your narrative as a Word document.
The ThermoStar Case
ThermoStar has been producing residential thermostats for over 50 years.
Looking over the past 20 quarters (5 years) of the different product lines, the general manager has been trying to get a handle on sales, costs, and production, and has asked for your help.
Answer the following using Excel and refer to your datasheet.
1. Calculate the descriptive statistics (summary statistics) for total sales (in K units), and report the mean, median, and standard deviation.
2. Using the unit data by product line, compile a breakdown of sales by product. Also, show the expected sales by product for 100,000 total units.
3. ThermoStar tests thermostats so they are calibrated with a mean of 70 degrees, with an associated standard deviation of 2 degrees. Given this mean and standard deviation what percentage of thermostats will test below the inspector’s cutoff value and thus need to be recalibrated? (See the data sheet for the cutoff and assume that the test results are normally distributed.)
4. A sample of 40 employees showed the average time spent in training per year to be 40 hours, with the associated standard deviation as noted in the datasheet. Construct a 95 percent confidence interval for the training program.
5. Do a simple regression for the total costs. Report the regression equation, as well as the R2 and tstatistic. Is this model suitable for business decision making? Explain why. (Hint: copy and paste special, transpose the data into columns, then run the regression tool.)

For the manufacturing plant discussed in Exercise 8.10, the union president and the human resources director jointly select a simple random sample of 36 employees to engage in a discussion with regard to the company’s work rules and overtime policies. What is the probability that the average number of overtime hours last year for members of this sample would have been less than 65.0 hours? Between 55.0 and 65.0 hours?