Common Questions v3 ALREADY PASSED

Variation in production systems that is caused by factors that can be clearly identified and possibly even managed is called assignable variation. - ANS True An example of assignable variation in a production system may be that workers are not identically trained - ANS True An example of assignable variation in a production system may be that a machine is not adjusted properly - ANS True Variation that is inherent in a production process itself is called assignable variation. - ANS False Variation that is inherent in a production process itself is called common variation. - ANS True It is impossible to have zero variability in production processes. - ANS True Genichi Taguchi's view of the cost of quality is that variance is a discontinuous function - ANS False The capability index is used to gauge economic changes in service systems. - ANS False Process control is concerned with monitoring quality after the product or service has been produced. - ANS False Statistical process control involves testing random samples of output from a process to determine whether the process is producing items within a preselected range. - ANS True Measurement by attributes means taking a sample, measuring the attribute in question, and determining the level of quality in the population from which the sample was drawn. - ANS False Attributes are those quality characteristics that are classified as either conforming or not conforming to specification - ANS True A p-chart has upper and lower control limits expressed as lines on the chart. As long as the sample values fall between these two lines, there is no need to investigate process behavior - ANS False The p-chart is only useful for sampling that deals with continuous variables. - ANS False The value for "z" used in quality control charts is based on the degree of confidence you want to have in the resulting UCL and LCL values. - ANS True If the fraction defective is 0.12 based on a sample size of 16, the standard deviation used in the p-chart is about 0.08. - ANS True If the fraction defective is 0.4 based on a sample size of 100, the standard deviation used in the p-chart is about 0.10. - ANS False To obtain a 99.7 percent confidence level in a p-chart, we would use a value of 3 for "z". - ANS True Acceptance sampling is performed on goods that already exist to determine what percentage of items conforms to specifications - ANS True In acceptance sampling, the number of units in the sample (n) is determined by the interaction of the acceptable quality level (AQL), the lot tolerance percent defective (LTPD), the probability of rejecting a high-quality lot (alpha), and the probability of accepting a low-quality lot (beta). - ANS True In acceptance sampling, the value for the acceptance number (c) is determined by the interaction of the acceptable quality level (AQL), the lot tolerance percent defective (LTPD), the probability of rejecting a high-quality lot (alpha), and the probability of accepting a low-quality lot (beta). - ANS True AQL stands for accepting questionable lots in production quality management - ANS False LTPD in acceptance sampling stands for lot tolerance for parts defective. - ANS False The Greek letter alpha is associated with consumer's risk - ANS False The probability associated with rejecting a high-quality lot is denoted in acceptance sampling with the Greek letter alpha. - ANS True The probability associated with accepting a low-quality lot is denoted in acceptance sampling with the Greek letter alpha. - ANS False The producer's risk associated with rejecting a high-quality lot is denoted in acceptance sampling with the Greek letter beta - ANS False Total, 100 percent inspection can never be cost justified - ANS False One hundred percent inspection is justified when the cost of inspection is low. - ANS False Sampling plans are generally displayed graphically through the use of operating characteristic (OC) curves. - ANS True The capability index (Cpk) calculates the percentage of items being produced within specifications - ANS False The capability index (Cpk) indicates the position of the mean and tails of a process's variance relative to design specifications - ANS True Standard practice in statistical process control for variables is to set control limits so that 95 percent of the sample means will fall within the UCL and the LCL. - ANS False In variables sampling, the actual measurements of the variable observed are used regardless of whether the unit is good or bad. - ANS True In monitoring process quality, we might use which of the following statistics? A. Absolute values B. Percentage deviation from tolerance centers C. "k" values for the sample mean D. Logarithmic control intervals E. Difference between the highest and lowest value in a sample - ANS E You have just used the capability index (Cpk) formulas to compute the two values "min [2, 2.5]." Which of the following is the proper interpretation of these numbers?