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2. Introduction . When evaluating laboratory results, how do we determine that is normal or acceptable? In other words: What is
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1. 1 MLAB 2401: Clinical Chemistry Quality Control, Quality Assessment and Statistics
2. 2 Introduction
When evaluating laboratory results, how do we determine that is normal or acceptable? In other words: What is “normal” or “OK”?
When does a laboratory test result become “weird” or “abnormal” ? When do be become uncomfortable with a result?
At some point we have to draw a “line in the sand” … on this side of the line you’re normal … on the other side of the line you’re abnormal. Where and how do we “draw the line” ?
Answer: Statistics are used to determine the lines of ‘normal’ and ‘acceptable’.
3. 3 Introduction
Statistics is used to draw “lines in the sand” for patient specimens, control specimens and calibrators
If the results are “normal” we ‘re comfortable about them and don’t worry
But if they’re abnormal, we’re uncomfortable and we fear that there is something wrong with the patient or that
something is wrong with the test procedure
4. 4 Statistical Concepts
Statistics is a (science of )branch of mathematics that collects, analyzes, summarizes and presents information about “observations.”
In the clinical lab, these “observations” are usually numerical test results
A statistical analysis of lab test data can help us to define normal ranges for patient’s ( normal and abnormal ) and acceptable ranges for control specimens ( “in” and “out” of control )
5. 5 Statistical Formulas Standard Deviation (SD) Is a mathematical expression of the dispersion of a group of data.