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1. Recovery Study: A new test for the drug Tacrolimus is going to be introduced into the lab. A recovery study needs to be performed before it is introduced. Samples from patients taking the drug were analyzed by the new method (column #2) then an additional drug was added (spiked) into the patient sample and re-tested with the new method (column #3). For each patient sample:
   1. calculate the % recovery given the data below
   2. do you notice anything about the %recovery data?

Patient Sample #	Patient Sample result with no added drug (ug/ml)	Patient sample result with 0.1 ug of drug added	% recovery
1	6.0 ug/ml	6.09 ug/ml
2	6.3 ug/ml	6.4 ug/ml
3	8.6 ug/ml	8.73 ug/ml
4	13.0 ug/ml	13.4 ug/ml

2. Interference Study: A new method for glucose is going to be introduced into the lab but an interference study with bilirubin needs to be performed first. Glucose levels were determined on patient samples (Column #2) then 0.15 mg of bilirubin was added to the Patient sample and re-tested with the new method (column #3).
   1. Calculate the interference and bias from bilirubin in each of the samples.
   2. Is the bias negative or positive and what does this mean?
   3. Is the bias constant or proportional and what does this mean?

Patient sample #	Glucose Result with no bilirubin added (mg/dL)	Glucose result with 0.15 mg bilirubin added (mg/dL)	interference	% bias
1	48	40
2	99 (use 92 instead)	80
3	122 (use 116 instead)	101
4	162	133

9.The lab wants to introduce a new testing method for the drug called “Xerox”. Currently Xerox is assayed on the Cobas instrument, but the lab has purchased a new instrument from Thermo called Thermo 2. You, the Lab manager, have performed a comparison of methods on patient samples over the course of one month on the 2 instruments and the data is below. Graph (and show the graph) of the data in Excel and determine if:

1. the methods are comparable and how explain you determined this
2. there is any constant error (negative or positive) with the new method and explain how you determined this
3. the reference range from the old method can be applied to the new method and explain how you determined this
4. what is the slope of the line?
5. what is the r² of the line?
6. What is the y-intercept of the line?

(Hint: you will also need to perform a linear regression in Excel or another program for this. There is a document under Course Content on linear regression in Excel)

Cobas instrument (ug/ml)	Thermo 2
245	220
339	350
227	225
590	600
127	120
56	68
333	300
402	410
387	380
336	340
272	220
290	295
325	320
495	520
199	180
180	185
100	99
129	130
150	145

10. What is the advantage of a Bland-Altman graph versus a scatter graph?
11. Describe how you would determine the analytical sensitivity (also called the limit of detection) of a test (how low a result can be detected with accuracy)?
12. Approximately how many samples need to be assessed to get a normal reference range? What other way could you get one?
13. The Director of the lab just asked you, the Lab manager, to write a new policy/procedure that establishes a maintenance schedule for the new chemistry instrument that was just purchased. How would you do this?
14. Define/describe corrective maintenance.
15. Why must logs be kept for maintenance and instrument repairs?

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