WEEK 15 QUALITY CONTROL CHART

QUALITY CONTROL CHART

Used to observe values of control materials over time to determine reliability of the analytical method.

Is utilized to observe and detect analytical errors such as inaccuracy and imprecision

Gaussian curve (bell-shaped curve)

Obtained by plotting the values from multiple analyses of a sample

Focuses on the distribution of errors from the analytical method rather than the values from a healthy or patient population

MEAN and SD.

When the data set can be accurately described by the?

mean.

A population probability distribution that is symmetric about the?

1 or 100%.

The total area under the curve is ________

Cummulative sum graph / CUSUM

Calculates the difference between QC results and the target means.

Gives the earliest indication of systematic errors (TREND) , and can be used with the 13s rules

Very sensitive to small, persistent errors that commonly occur in the modern, low calibration-frequency analyzer

V-MASK

Common method:

45 DEGREE

+/- 2.7 SD

Results are out of control when the slope exceeds _______ or a decision ________ is exceeded.

Youden or TWO-SAMPLE PLOT

Used to compare results obtained on a high and low control serum from different laboratories.

Shewhart levey-Jennings chart

MOST WIDELY used QC chart in the clinical laboratory.

Allows the laboratories to apply multiple rules without the aid of a computer.

RANDOM

SYSTEMATIC ERRORS

Easily identifies ______ and __________

TREND

SHIFT

OUTLIER

Errors observed on LJ chart

TREND

- formed by control values that either increase or decrease for 6 consecutive days

Main cause: DETERIORATION OF REAGENTS

SHIFT

formed by control values that distribute themselves on one side or either side of the mean for 6 consecutive days

Main cause: IMPROPER CALIBRATION OF THE INSTRUMENT

Outliers

control values that are far from the main set of values.

12s

used a rejection or warning rule when one control result exceeds the mean _____ ; for _______.

13s

one control result exceeds the means ____ ; it is effective in determining ________.

22s

the last 2 control results exceed either the mean ____ ; respond most often to ___________.

41s

the four consecutive control results exceed either mean _____ ; respond to _____________.

R4s

the range or difference between the highest and lowest control result within an analytical run exceeds _____ ; responds to ________ or ________

10x

ten consecutive results are on the same side of the target mean ; ___________.