If we want to detect small process shifts using x bar chart, we should use a sample size of:

Related MCQs

• Consider the first method of p bar estimation where each sample is of varying size. If the 3rd sample has p bar =.01, and the sample size of the 3rd sample is 10, what will be the upper control limit for the 3rd sample?
• Consider that for a process s bar (average standard deviation of 50 samples each of size 4) is found to be 10.04. The value of c4 (corresponding to sample size of .4) is .92. What is the estimated value of process standard deviation?
• You conduct a hypothesis test and you observe values for the sample mean and sample standard deviation when n = 25 that do not lead to the rejection of Ho (null hypothesis). You calculate a p-value of 0.0667. What will happen to the p-value if you observe the same sample mean and standard deviation for a sample n>25?
• Assume the cholesterol levels in a certain population have mean μ = 200 and standard deviation σ = 24. The cholesterol levels for a random sample of n = 9 individuals are measured and the sample mean x-bar is determined. What is the z-score for a sample mean x = 180?
• Factory A produces 100 pieces of wooden legs used in manufacturing tables in 1 hour. The factory in total works for 3 hours. The quality manager decided to check the quality of the output by measuring the length of the legs (in cms). He decides to collect three samples (one for each hour). The sample size for each sample is fixed at 5. The data collected is present in the following table: What is the mean and range of leg length in sample 1?
• An acceptance control chart has limits that are based on the specification limits for the product rather than limits which differentiate between random and assignable causes. Under which if the following circumstance should a QC manager consider using an acceptance control chart?
• For a given sample size (n) and number of defects acceptable ©, the Average Total Inspection (of units) should ______________ with increase in N (lot size).
• The basic assumption of calculating the control limits based on average sample size (for a p chart) will ______________ from/as those previously observed.
• Given L=3 and p=.03, estimate the sample size that can be used for construction of a p chart.
• The same quality control manager decides to increase his daily sample size from three to six. The size of the control band will: