PROCESSQUALITY ENGINEERINGMEASUREMENT SYSTEM AND ANALYSISASSIGNMENT – 1onBIAS SubmittedbySRINATHTHANGARAJRAJA8151813 EXECUTIVE SUMMARY:In this report, we are taking lengthof an ignition tube to find whether the observation values are biased or not,and the report is made by the values observed during the observation and the biasvalue is found using the formulas in excel and graph from Minitab which areshown to give clear results.REPORT:Example: As a quality assurance engineer I was evaluating theobservations of the product and analysis of the measurement equipment indicatedthat there should be no linearity concerns, so I had only the bias of themeasurement system evaluated. I took the measurement of the length of an ignitiontube in the motor bike which was measured by Vernier calliper in (mm)Thepart was measured with reference to layout inspection to determine itsreference value.
and was then measured 10 times to see the bias values. And the values of t statics and t critics arefound with standard deviation and standards error of the mean using theobserved value in excel.Reference value =19.920 Trial Observed Value(mm) Bias(mm) 1 20.
7521 0.8321 2 20.8523 0.
9323 3 20.7563 0.8363 4 19.
999 0.079 5 20.9214 1.0014 6 19.8923 -0.0277 7 20.7991 0.
8791 8 19.9976 0.0776 9 20.4464 0.5264 10 19.9812 0.0612 n Average Standard Deviation, Standard Error of Mean, b Measured Value 10 20.
4397 0.4254 0.1345 Reference Value = 19.920 ? =.
05 t statistic df Significant t value (2-tailed) Average Bias Confidence Interval of the Bias Lower Upper Measured Value 3.863 9 2.14479 0.
519 0.2154 0.824 GRAPHS FROM MINITAB:` Conclusion & result:From these graphs the value shows us that’sthe zero falls within the interval of bias so that I can assume that themeasurement bias is acceptable assuming no need of additional variation. Andmore over all the values are lesser than t-critic value showing us the productfalls under the rejection category. SO, thesystem is biased, and if the measurement has to be non-zero bias itpossibly should be recalibrated to achieve zero bias or the instrument shouldhave been worn out which should be maintained.
The bias study is performed toverify whether the instrument is measuring offset in a significant manner, thetests also reflects on the calibration state of instruments and establish the suitabilityof instruments to measure the process, the bias study should also be performedwhen the instrument is initiated into a new process. The calculations of the standarddeviation, standard error of the mean, average bias, lower limit and upperlimit are done in excel worksheets which are attached with this assignment.