tailieunhanh - Engineering Statistics Handbook Episode 9 Part 9

Tham khảo tài liệu 'engineering statistics handbook episode 9 part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | . Does the proportion of defectives meet requirements ENGINEERING STATISTICS HANDBOOK hW tools raids lỉEÂtCH BACK Nixf 7. Product and Process Comparisons . Comparisons based on data from one process . Does the proportion of defectives meet requirements Testing proportion defective is based on the binomial distribution Hypotheses regarding proportion defective Test statistic based on a normal approximation The proportion of defective items in a manufacturing process can be monitored using statistics based on the observed number of defectives in a random sample of size N from a continuous manufacturing process or from a large population or lot. The proportion defective in a sample follows the binomial distribution where p is the probability of an individual item being found defective. Questions of interest for quality control are 1. Is the proportion of defective items within prescribed limits 2. Is the proportion of defective items less than a prescribed limit 3. Is the proportion of defective items greater than a prescribed limit The corresponding hypotheses that can be tested are 1. p Po 2. p Po 3. p Po where p0 is the prescribed proportion defective. Given a random sample of measurements Y1 . Yn from a population the proportion of items that are judged defective from these N measurements is denoted p. The test statistic depends on a normal approximation to the binomial distribution that is valid for large N N 30 . This approximation simplifies the calculations using critical values from the table of the normal distribution as shown below. http div898 handbook prc section2 1 of 3 5 1 2006 10 38 35 AM . Does the proportion of defectives meet requirements Restriction on sample size One and two-sided tests for proportion defective Example of a one-sided test for proportion defective Calculations for a one-sided test ofproportion defective Because the test is approximate N needs to be large for the test to be valid. One .