Statistical Quality Control in Textiles
Statistical Quality Control in Textiles
ASSIGNMENT
Module 1: Introduction to Quality and Quality Control
Q1)Dodge and Romig are known for providing the concept of
(i)Acceptance sampling plan
(ii)Control chart
(iii)Six sigma
(iv)Zero defect
A1: (i)
Q2)What is quality control?
(i)Quality control describes the ways for making money in business.
(ii)Quality control describes the directed use of testing to measure the achievement of a specified standard.
(iii)Quality control describes the ways to control of the consumer demands.
(iv)None of the above.
A2: (ii)
Module 2: Statistical Description of Quality
Q1)The difference between the value of the cumulative distribution function of a variable and the same of its standardized variable is
(i)Positive
(ii)Negative
(iii)Zero
(iv)Infinity
A1: (iii)
Q2)How many parameters do the normal distribution has?
(i)One
(ii)Two
(iii)Three
(iv)Four
A2: (ii)
Module 3: Statistical Inferences of Quality
Q1)Which of the following statements is true?
(i)The sample mean is an unbiased estimator of population mean, but the sample variance is a biased estimator of population variance.
(ii)The sample mean is a biased estimator of population mean, but the sample variance is an unbiased estimator of population variance.
(iii)Both the sample mean and sample variance are the unbiased estimators of population mean and population variance, respectively.
(iv)Both the sample mean and sample variance are the biased estimators of population mean and population variance, respectively.
A1:(i)
Q2)Let be a random variable. A random sample is formed by taking items from a population and the mean of the sample is denoted by .
Which of the following statements is true?
(i)is equal to sample variance.
(ii) is equal to population variance.
(iii) is a biased estimator of population variance.
(iv) is an unbiased estimator of population variance.
A2:(iii)
Q3)Which of the following statements is false?
(i)Type I Error refers to rejectionthe null hypothesis when it is true.
(ii)Type I Error refers to acceptance of the null hypothesis when it is false.
(iii)Type II Error refers to acceptance of null hypothesis when it is false.
(iv)As the probability of Type I Error increases the probability of Type II Error decreases.
A3:(i)
Module 4: Shewhart Control Charts
Q1)In Poission distribution,
(i)The mean is equal to the standard deviation.
(ii)The mean is equal to the square root of standard deviation.
(iii)The mean is equal to the variance.
(iv)The mean is equal to the square of the variance.
A1:(iii)
Q2)Which of the following statements is correct?
(i)The Shewhart control chart is not able to detect a large shift in process mean.
(ii)The Shewhart control chart is not able to detect a large shift in process variance.
(iii)The Shewhart control chart is not able to detect a small shift in process mean.
(iv)The Shewhart control chart is not able to detect a small shift in process variance.
A2:(iii)
Module 5: Process Capability Analysis
Q1)Which of the following statements is true?
(i)Both Cp and Cpk can be negative?
(ii)Cp cannot be negative, but Cpk can be negative.
(iii)Cp can be negative, but Cpk cannot be negative.
(iv)Both Cpand Cpkare always positive.
A1:(ii)
Q2)Which of the following statements is true?
(i)Both Cp and Cpk can be negative?
(ii)Cp cannot be negative, but Cpk can be negative.
(iii)Cp can be negative, but Cpk cannot be negative.
(iv)Both Cpand Cpkare always positive.
A2:(ii)
Module 6: Non-Shewhart Control Charts
Q1)Which of the following statements is correct?
(i)In MA control charts the control limits are same for all observations.
(ii)In MA control charts, for the initial periods iwthe control limits are narrower than their final steady-state value.
(iii)In MA control charts, for the initial periods iw, the control limits are wider than their final steady-state value.
(iv)None of the above.
A1:(iii)
Q2)Which of the following statements is correct?
(i)The Cusum control chart, MA control chart, and EWMA control chart are equally effective in detecting small shift in process mean.
(ii)The Cusum control chart is less sensitive in detecting small shift of process mean than the MA control chart and EWMA control chart.
(iii)The MA control chart is less sensitive in detecting small shift of process mean than the Cusum control chart and EWMA control chart.
(ii)The EWMA control chart is less sensitive in detecting small shift of process mean than the Cusum control chart and MA control chart.
A2:(iii)
Module 7: Acceptance Sampling Techniques
Q1)Which of the following statements is correct?
(i)The ideal OC curve always gives high value of probability of acceptance than the practical OC curve.
(ii)The ideal OC curve always gives less value of probability of acceptance than the practical OC curve.
(iii)The ideal OC curve always gives the same probability of acceptance, regardless of values of proportion of defectives in the lot/batch.
(iv)None of the above.
A1:(i)
Q2)Which of the following statements is incorrect?
(i)As the sample size n increases, the OC curve becomes more like idealized OC curve.
(ii)Plans with higher value of sample size offers more discriminatory power.
(iii)The higher value of sample size results in lower value of probability of acceptance for given values of proportion of defective and acceptance number.
(iv)All of the above
A2:(iii)
Q3)Which of the following statements is correct?
(i)Plans with smaller value of acceptance numberprovide same discrimination as plans with larger values of acceptance number.
(ii)Plans with higher value of acceptance numberprovide discrimination at lower levels of lot fraction defective than do plans with smaller values of acceptance number.
(iii)Plans with smaller value of acceptance number provide discrimination at lower levels of lot fraction defective than do plans with larger values of acceptance number.
(iv)All of the above
A3:(iii)
Module 8: Six sigma
Q1)Which of the following statements is correct?
(i)Under three sigma, the parts per million defective is 0.002 when the process is shifted 1.5 times the standard deviation from the target and normally distributed.
(ii)Under six sigma, the parts per million defective is 0.002 when the process is shifted 1.5 times the standard deviation from the target and normally distributed.
(iii)Under six sigma, the parts per million defective is 3.4 when the process is shifted 1.5 times the standard deviation from the target and normally distributed.
(iv)None of the above
A1:(iii)