120 Chapter 3 Describing Data Using Numerical Measures Case 3.1 SDW-Human Resources SDW is a large international construction company. The company was a major player in the reconstruction efforts in Iraq. However, the company is also involved in many small pro jects both in the United States and around the world. One of these is a sewer line installation project in a Midwest city. The contract is what is called a "cost plus contract, meaning that the city will pay for all direct costs, including materials and labor of the project plus an additional fee to SDW. Roberta Bernhart is the human resources (HR) manager for the project and is responsible for over seeing all aspects of employee compensation and HR issues SDW is required to produce a variety of reports to the city council on an annual basis. Recently, the council asked SDW to prepare a report showing the current hourly rates for the nonsala- ried work crew on the project. Specifically, the council in inter ested in any proposed pay increases to the work crew that will ultimately be passed along to the city. In response to the city's request. Roberta put together a data file for all 19 nonsalaried work crew members, called SDW, which shows their current hourly pay rate and the proposed increase to take place the first of next month The city council expects the report to contain both graphic and numerical descriptive analyses, Roberta has outlined the following tasks and has asked you to help her. Required Tasks: 1. Develop and interpret histograms showing the distribution of current hourly rates and proposed new hourly rates for the crew members. 2. Compute and interpret key measures of central tendency and variation for the current and new hourly rates. Determine the coefficient of variation for each 3. Compute a new variable called Pay Increase that reflects the difference between the proposed new pay rate and the current rate. Develop a histogram for this variable, and then compute key measures of the center and variation for the new variable. 4. Compute a new variable that is the percentage increase in hourly pay rate. Prepare a graphical and numerical description of this new variable. 5. Prepare a report to the city council that contains the results from tasks