Southwest Tube of Oklahoma is a small fabricator of specialty tubes used in boilers and other equipment. Southwest buys the tubes in long segments and cuts, bends, cold draws, and welds the pieces to make what is needed for the products. A few years ago Southwest Tube was facing tough competition. The prices were falling while the costs were rising. To improve productivity, consultants were brought in. They pointed out problems with labour turnover, absenteeism, weak supervision, staffing mismatch, lack of performance goals, and a dislike for the weekly rotating schedule as causes of the problem. One of the solutions tried, in addition to other improvements, was changing the work schedule to four 12-hour days followed by three days off. The productivity seemed to improve gradually. To ascertain this, the following data for two physically demanding work centres were collected starting the year before the change in work schedule.