Quality Associates Case Study

Quality Associates, Inc. Report A company has approached Quality Associates, Inc. to verify that their sampling and statistical procedures are working efficiently. A sample of 800 units has been taken for observations for the study while operations were known to be operating at satisfactory levels. .21 has been set as the sample standard deviation and likewise so has the population standard deviation assumed to be .21 because there are a substantial amount of observations. Random samples of 30 will allow for swift action if said processes are not producing at efficient levels or drop below an average of 12 units, the null hypothesis, which has been set for this particular operation. Corrective action shall be taken anytime the experimental hypothesis tested does not equal 12.
Taking 30 samples at continuous hourly intervals four times during the day and hypothesis testing them resulted in corrective action being taken one out of three times. The first sample had a test statistic of -1.027 which led to sample 1 being .303 above the given acceptable levels. The second hypothesis test statistic equaled .713 with a .169 above the first sample’s level of significance and was also not rejected. The third sample resulted in a test statistic reading of -2.935 with a level of significance .004 below the acceptance level of .01 and corrective action was taken. The last sample delivered a test statistic of 2.161 and a .039 significance level with no corrective action because it was .029 above the level of rejection.
Further testing of the data with the four samples produced standard deviations of .22036, .22036, .20717, and .206611, respectively. All four samples are reasonably within the set assumption of .21 which can safely be assumed as to be a reasonable point estimator for this sampling operation because the variation is not outrageously outside of the mean set.
With a population mean of 12 the process would be deemed as operating satisfactorily because the