answer the following questions
Question Description
Use alpha=0.05 unless otherwise instructed.
A research lab employs technicians who run many tests that involve the use of micropipetters. In a recent audit of the lab data, it has been found that there is too much variability in the results from these tests. The lab director decides to recalibrate the pipets. However, a quick walk through the lab reveals that certain employees may not be properly trained because they are using improper pipetting techniques.
1. Jim, a relatively new hire, pipets aliquots of test solutions into a well plate. He is supposed to be pipetting 50 uL into each of 8 wells. However, after taking look at the results of Jim’s tests, the director finds that Jim was putting an average of 48.1 uL into each well, with a standard deviation of 2.3 uL (the nature of the test allows the true amount of solution added to be back-calculated from the results). Is Jim pipetting a significantly lower amount of test solution into the wells than he is supposed to be?
2. Kelly has been working in the lab for over 5 years. She has performed the same test as Jim did in the previous question many times. The lab director reviews the last 11 tests of this type that Kelly has performed. Kelly added an average of 50.2 uL of solution to each well, with a standard deviation of 0.44 uL. Is there a significant difference between the amount that Jim is adding to each well and the amount that Kelly is adding to each well? Use the data from the previous problem for Jim’s statistics. You can assume that the differences in experience mean that Jim and Kelly have different variability in the amounts they pipet.
3. Failure Mode and Effect Analysis is commonly used for processes, but can also be used for laboratory activities. The lab director is considering performing an FMEA on activities in the lab, including the testing involving micropipetting. Based on your experience with lab work, describe three common failures that can happen in a laboratory setting and how an FMEA can be used to minimize the severity and occurrence, and maximize the detection of these failures.
4. The lab director, having sorted out the pipet issue, is now focusing on the output of a pilotscale bioreactor. The performance of the oxygen sparger has been iffy recently and the average dissolved oxygen concentration in the tank is currently 72%. The past 9 measurements of the dissolved oxygen content have ranged between 71.5% and 72.3%. The dissolved oxygen content should be between 70.5% and 73.5%. a. What is the process capability for the oxygen sparger? b. What are Cp and Cpk? c. Based on your answer to part b, what can be said about the ability of the process to stay within the specified limits for dissolved oxygen content? Is the process currently staying in those limits?
5. After talking with several of the technicians about the bioreactor, the lab manager decides to run some experiments on the bioreactor. Four different dissolved oxygen levels are used and the output of the bioreactor is measured for each level. Testing is performed in duplicate. The ANOVA table is below.
Source of Variation
Sum of Squares DoF
Mean Square F0 Treatments 447.0 149.00 2.048 Error 291.0 72.75 Total 738.0
a. What is the factor for this ANOVA test? b. What is the null hypothesis? The alternative hypothesis? c. How many total observations are there? d. Complete the ANOVA table. e. Are there any significant differences? How do you know?
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