Quality Management Flashcards
The higher the SD result means
lower precision
- SD result of >2 indicates
- SD result should be <2
a. lower precision
b. higher precision
A B
Percentile expression of the mean. Aka Total Percent Error. Index of precision.
Coefficient Variation
Formula of CV
CV= SDx100/Mean
Limits between which we expect a specified
proportion of population to lie
Confidence limits
standard reference limit for normal distribution
95%
Normal Frequency Curve, Normal Distribution
Curve
Gaussian Curve
Also known as Bell-shaped curve
Gaussian Curve
this is where you plot the result, where SD are placed
Y-axis
this is where you plot the frequency, where DAYS are placed
X-axis
CUSUM data elements are centered around the mean
with most elements close to the mean. TRUE OR FALSE.
False
If a random error is present the curve in gaussian curve becomes
wider & shorter
Used to compare results using different
samples or one sample using two different
methods and for systematic error detection
Twin plot
In bell-shaped curve, one specimen will be plotted to the Y axis and the other specimen will be plotted to the X axis. TRUE OR FALSE.
False
Calculates the difference between QC results
and the target means
Cumulative sum graph
Most widely used system in clinical laboratories. A graphic representation of the acceptable limits
of variation in the results of an analytical method. Detects both random and systematic error.
Shewart Levey-Jennings chart
Levey-Jennings Chart: Before plotting this chart, you have first to compute for the 8 statistical parameters
specifically, the SD and the Mean. TRUE OR FALSE.
True
Done by subtracting the mean from the
individual values and the cumulative differences
are plotted. Give the earliest indication of systematic error.
Cumulative sum graph
The mean should be written in one solid line
whereas the confidence limit should be written
using broken lines when making
Shewart Levey-Jennings chart
Control values that lies in _SD and _SD and beyond is a sign of potential problem. You have to run a new
control and repeat specimen testing.
2 & 3
is considered in control when
there is symmetrical distribution of control values
about the mean and there are only few control
values outside the 2SD control limit
Analytical method
Errors which can be observed on LJ chart: Gradual change in the mean that proceed in one direction. Control values either increases or decreases for six consecutive days.
Trend
Causes of trend are improper calibration of
instrument, new lots of standards and reagents. TRUE OR FALSE.
False
Causes of shift are deterioration of reagents, light
source, control materials. TRUE OR FALSE.
False
An abrupt change in the mean that becomes continuous. Control values that distribute themselves on one side or either side of the mean but do not pass the mean for six consecutive days.
Shift
Also known as “Multirule Quality Control” used in the laboratory for internal and external QC.
Westgard Control Rule
Control rule to indicate if the analytical process
is “in control” or “out of control”
Westgard Control Rule
One control result exceeds the mean by more than +/- 2SD & 3SD should be rejected (random error). TRUE OR FALSE. What error is that?
True, 12s &13s
Two consecutive control results/days exceed the mean by 2 more than 2SD is a systematic error. TRUE OR FALSE. What error is that?
True, 22s
Four consecutive control results/days exceeds the mean by more than 1 SD should not be rejected (systematic error). TRUE OR FALSE. What error is that?
False, 41s
Difference between two consecutive
controls is greater than 4SD are responsive to random errors. TRUE OR FALSE. What error is that?
True, R4s
Ten consecutive results are on the same
side of the target mean.
10x
Set of control and patient specimens assayed,
evaluated and reported together
Analytical Run
Current results compared to the previous/past
results
Delta Check
Measured concentration is equal to the actual
concentration
Linear Range
Analytical testing performed outside the confines
of the central lab usually by non-laboratorian
personnel (nurses)
Point of care testing
Used to measure systematic errors or
inaccuracy caused by substances other than the
analyte
Interference testing
Most common interference that could affect the result a. Hemoglobin b. Lipids, c. bilirubin d. anticoagulants e. a and b f. all of the above g. none
F
Studying those specific compounds affect the
accuracy of the laboratory test
Interference studying
Interference is equal to concentration with interference added divided by the concentration without interference. TRUE OR FALSE
True
Show whether a method measures all the
analytes or only part of it
Recovery Experiment
Results obtained from a single individual or group. Requires 100 or 120 patients.
Reference limit
Method is able to accurately measure an analyte. Patient sample (matrix) and aliquot of concentration analyte (spiked). Determine how much of analyte can bedetected in presence of all other compounds in
the matrix
Recovery studies
50th percentile
Median
