STATISTICAL CONCEPTS in QUALITY CONTROL Flashcards
A statement of the extent of random variation in any series of measurement
STANDARD DEVIATION
A measure of the distribution of values around the mean
STANDARD DEVIATION
Square of the standard deviation
VARIANCE
Used to detect significant differences between groups of data
VARIANCE
Determine contributions of various factors to the total variation
VARIANCE
Percentile expression of the mean
COEFFICIENT OF VARIATION
Measure of the relative magnitude of variability
COEFFICIENT OF VARIATION
CV = s (100)/X
COEFFICIENT OF VARIATION
Reported values do not fall along the line of slope when graphed
Analytical Bias
Reported lab results do not correspond to the correct value
Analytical Bias
Problem on Accuracy (Bias) = ____________
Systematic error
Refers to laboratory analyses that are subject to imprecision
Random Analytical Variability
Problem on Precision (CV) = _____________
Random Error
can be systematic or personnel-related
Errors
Sources cannot be completely controlled or identified
RANDOM ERRORS
Increase the extent of variability of results
RANDOM ERRORS
Displace the mean value on one direction (may be up or down), but do NOT affect the overall variability as shown by the SD value
SYSTEMATIC ERRORS