2020 Issue

39 Family of Measure Question Unit of Measure Examples Count Measure Productivity (units) How many? Units (calorie, meter, °C, liter, amp, cm3, psi, volt, kg, mole) Scrap, rework, repair, pass, fail, throughput, waiting calls, returns, call abandonment, load, available rooms, fill level, capacity, available seat miles Weight, height, length, temperature, volt, area, volume, pressure, distance, power, fuel economy, mass, energy, illumination, force, stress, current Financial (currency) How much? $, €, ¥ Cost, profit, budget, assets, revenue, debt, income, sales, expenses Taken to decimals (often treated as variable but remains an attribute for determining sample size) Quality (Index) How well? Index Survey scales (1, 2, 3, 4, 5) Customer satisfaction, employee satisfaction, patient satisfaction, student grades Satisfaction survey slider scales (1-5) Control plan indices, patient safety index, blood pressure, process capability indices, Cp & Cpk Timeliness (time units) How fast? sec, min, hour, day, week, month, year Counts of whole months, weeks, days, or hours (1, 2, 3, …) Age, days late, seniority, tenure, block hours Cycle time, handle time, duration, intervals, queue time, shipping time, response time, MTTF, MTBF, MTTR, lead time, delay, call time, setup time Combinations (%) At what rate? rate, % Labor rate, yield, return rate, load factor, return on assets, payout ratio, gross margin, mortality rate, occupancy %, average daily rate, revenue per room, advertising ROI, average daily rate, domestic book rate, website conversion rate, asset turnover ratio, stage length, profitability ratio, inventory turnover, speed Table 1 Family of Measure Definitions A Universal Concept The four metrics are represented in many fields of study. Project management embeds the Family of Measures in its core knowledge areas: scope management, time manage- ment, cost management, and quality management (Project Management Institute, 2008). Scope, activity planning, and the work breakdown structure are productivity elements. Timeliness is represented by the schedule, displayed with Gant charts and networks. The project budget is the financial portion. Variance indices represent quality efforts. Project risk management (FMEA) also contains the family of measures embedded in severity (quality), detection (productivity), and occurrence (timeliness or productivity, depending on the scale). Logistics is another example of this universal concept. Logistics has five objectives: right product and place, right time or faster, right price/cost, and right condition (Stock and Lambert, 2001). The Family of Measures is a reoccurring schema that appears in all disci- plines, although each may be worded differently. Productivity versus Quality Metrics The Taguchi Loss Function (Deming, 2000) is probably the best illustration of the difference between productivity and quality. A simple loss function is a step function between two states of a switch (on/off). The light is either on or off. Figure 2 illustrates production yields as a loss function. Figure 2 Traditional View of Loss