method of evaluation Flashcards
More than how many percent of the diagnosis are coming from
the laboratory.
70%
short-term monitoring of
accuracy precision inside a laboratory is termed
as your internal quality control (Everyday),
quality control
Monitoring of the long-termed of accuracy and
precision inside your clinical chemistry laboratory
and that is __- they are being given to us by the National
Reference Laboratory for NEQAS for proficiency
testing
external quality control (Monthly)
The foundation for monitoring performance (known as QC) is
___.
descriptive statistics
Assessment of data dispersion, or spread, allows
laboratorians to assess the predictability (and the lack of) in a laboratory test or measurement.
Descriptive Statistics
Assessment of data ___, or spread, allows
laboratorians to assess the predictability (and the lack of) in a laboratory test or measurement
dispersion
disadvantage of using bovine based qc
not recommended for dye binding assay
not recommended for certain bilirubin assays
not recommended for immunohistology chemistry
to look for the accuracy, we need to find the __
mean
to look for the mean, we need to compare ___
t test
to find accuracy, we need to find mean, to find mean, we need to compare t test
accuracy
mean
t test
true or false
true
to find the precision/systematic error
we need to look for the f test and standard deviation
true or false
true
what is the component of the quality control chart
mean and standard deviation
It detects the accuracy
mean
it detects the precision
standard deviation
The three most commonly used descriptions of the center of a
dataset are the mean, the median, and the mode.
Measures of Center
The three most commonly used descriptions of the center of a
dataset are the ___,__ and ___
mean, the median, and the mode.
is most commonly used and often called the average. Add all the data and divide the number of data
mean
it is The measure of center (mean), spread (how far) and shape
(bell shaped
descriptive statistics
to know the dispersion and how spread the data, we look for the ___
standard deviation
descriptive statistics is composed of 3 things
center
spread
shape
to look for the center we look for the __-
mean
a quality control material should always follow bell shape called
gaussian distribution curve
the area under our bell shape curve is always
100 %
the data in the gaussian curve is always __ which means the data on the left side mirrors the right side
symmetrical
if the gaussian curve is not symmetrical, it means that the data are ___
skewed
the top of the bell shape curve inidcates the
mean
what is the value of 1sd
68.3
we can determine how spread the data from the true value based from the ___
mean
a limit which the data is no longer acceptable
farther than 2sd
is the “middle” point and is often used with skewed data
so its calculation is not significantly affected by outliers.
median
is rarely used as a measure of the data’s center but is
more often used to describe data that seem to have two
centers (i.e., bimodal)
mode
means can be symbolizes as
X bar or a summation sign
three commonly used measurement of spread - precision
range
standard deviation
coefficient variation
least commonly used measurement of spread - prcision
range
most commonly used measurement of spread - prcision
standard deviation
formula for stanrd deviation index
data - mean divide them all by SD
formula for rnage
high - low
a measurement of spread that can be used for small data or sample
range
formla for variance
the summation of the quantity squared of X - mean
divided them all by n-1
formula for stadard variation
squareroot of variance
measure of shape
1 sd
68.3
measure of shape
2 sd
95.7
measure of shape
3 sd
99.5
it is the squared of all the data around the mean
variance
Is one description of the spread of data. It is simply the
difference between the highest and lowest data points:
range
what is the unit for coefficient variation
%
formula for coefficient variation
SD / mean x 100
what is the ruling for coefficient variation
the higher CD lower precision
all of the precise instrument should have a coefficient of variation of how many percent
less than 1%
A solution of known characteristics and of known value or whose concentration is accurately known
standard solution
a solution that is for accuracy
standard solution
a solution that is for precision
control solution
it is composed of one known constituent only and used as
a basis of reference for the calculation of the value of the
unknown.
standard solution
this solution is 100% pure
standard solution
a solution that Serve as a reference for unknown
standard solution
A solution without the specimen.
blank solution
It is the statement of the extent of variation in any
series of measurement
standard variation
It is a measure of the distribution range of values
around the mean value or average
standard variation
it is the measure of spread of data
sd
It is the percentile expression of the mean which
is measure of the relative magnitude of variability.
coefficient of variation
It is the ratio of the standard deviation over the
mean expressed in percent
coefficient of variation
It is a statement of variability and measures the
significant differences between groups of data
variance
Most commonly used chart
shewhart-levey jennings chart
Also referred as a Levey-Jenning chart, S-L/J
shewhart-levey jennings chart
also known as dot chart
shewhart-levey jennings chart
the most important chart in cchm that detects all types of error
shewhart-levey jennings chart
this qc chart is a graphic representation of the acceptable limits of variation in the results of an analytical method
shewhart levey-jennings chart
this qc chart allows the laboratorian to apply multiple rules without the aid of a computer
shewhart levey-jennings chart
It will group any series of measurement in the
same sample in a cluster around the mean in a
bell shaped curve
gaussian curve
what is our reference interval
95%
any data that fall outside the reference interval or confidence limit is an ___
outlier or out of control
5 or more consecutive data either increasing or decreasing that pass through the mean is called
trend
what is the common cause for trend?
deterioration of reagent
an up and down data withot passing the mean is called
5 consecutive data that fall either on one side of the mean
shift
what is the common cause of shift?
improper calibration of instrument
abrupt change will show a data __
shift
progressing
trend
gradual
trend
what type of water we are using for control solution
typeII wwater
what grade of water we are using for control solution
analytic/reagent grade
A solution (either commercially or non-commercially
prepared) composed of several known constituents which
can be run simultaneously with the test to check the
accuracy of the results. (
control solution
a solution that is Stable for a long period of time
control solution
When to Perform Quality Control
- Beginning of each shift (Daily testing)
- New instrument
- After an instrument is serviced
- When reagent lots are changed (yearly)
- After calibration
Whenever patient results seem inappropriate
a histogram that detects all type of error
shhart-levey jennings chart
a chart Plotted with the accumulated differences from the
mean of individual values with the middle value
being zero.
Cumulative Sum Graph
a chart that should always be computerized
cumulative sum graph
a chart that is used to compare the result when there’s changes in the mean and in the target value
cumulative sum graoh
a chart used to compare the results of different laboratories
youden plot
which of the rule is considered as a mandatory rule
1 3s
which of the rule that is classified as a warning rule
1 2s
States that 1 controlled value exist ± 2 standard deviation
from the mean.
1 2s
what type of error is outlier/
random and systematic
type of error of trend
systematic
type of error of shift
systematic
in order to create a reference value, we need to test how many samples?
120-700 samples
this qc chart is used when the data set can be accurately described by the SD and the mean
gaussian curve
this qc chart easily identifies random and systematic error
shewhart levey-jennings chart
this qc chart is used for population probability that is symmetric about the mean
gaussian curve
this qc chart is used when the data elements are centered around the mean with most elements close to the mean
gaussian curve
this qc chart focuses on the distribution of errors from the analytical method rather than the values from a healthy or patient population
gaussian curve
this qc chart is used to calculate the difference between the QC results and the target means
cumulative sum graph (CUSUM)
common method of CUSUM
V-mask
this qc chart is used to identifies consistent bias problems
CUSUM
this qc chart requires computer implementation
CUSUM
this qc chart will give the earliest indication of systematic errors (trend) and can be used with the 1s3 rule
CUSUM
this qc chart is very sensitive to small, persistent errors that commonly occur in the modern, low calibrations-frequency analyzers
CUSUM
in CUSUM, how to consider an out of control result
when the slope exceeds 45* or a decision (+- 2.7 SD) is exceeded
this qc chart is used to compare results obtained on a high and low control serum from different laboratories
youden/twin plot
this qc chart is used to display results of the analyses by plotting the mean values for one specimen on the ordinate (y axis) and the other specimen on the abscissa (x axis )
youden/twin plot
youden/twin plot can distinguished constant and proportional systematic error,
explain how
proportional:
the points falling from a center but ON THE 45* line
constant:
the points falling from a center but NOTON THE 45* line
is formed by control values that either increasing or decreasing for 6 consecutive days
trend
shift
shift in the reference range is due to
transient instrument differences
it is formed by control values that distribute themselves on one side or either side of the mean for 6 consecutive days
shift
main cause of trend
deterioration of reagents
main cause of shift
improper calibration of the instrument
shift is an example of what error
systematic error
trend is an example of what error
systematic
these are control values that are far from the main set of values
ourliers
these are highly deviating values
outliers
these are caused by both random and systematic errors
outliers
this qc control chart recognizes that the use of simple upper and lower control limits is NOT ENOUGH to identify analytical problems
westgard control chart
in this qc control chart, error detection rates increase without increasing the false rejection rate
westgard control chart
westgard used the term ___ to indicate if the analytical process is out of control
control rule
westgard control rule
rejection or warning rule when one control result exceeds the mean 2SD; for screening purposes; it has large false alert rate
1-2 s
westgard control rule
it is observed when one control result exceeds the mean 3sd; due to random error; has low false alert rate
1-3s
westgard control rule
when the last 2 control results (or 2 results from the same run) exceed either the mean SDF; due to systematic error
2-2s
the last 4 (or any 4) consecutive controls result exceeds either mean 1SD
4-1s
westgard control rule
the range or difference between the highest and lowest control result within an analytical run exceeds 4s
R4s
westgard control rule
reject an analytical run when 6 consecutive control measurements fall on one side of the mean
6x
westgard control rule
reject analytical run when 7 control measurements “trend” in the same direction
7t
westgard control rule
do 10x has hiugh false alert
yes
in establishing new reference intervals, how many individuals are must be tested
120
ideally, laboratory should have __ an d__ stratified reference ranges on all populations tested
age and sex stratified
the verification of already existing and esetablishing reference intervals, CLSI permits how many subject specimens/individuals
20
