Errors in Chemical Analysis Flashcards
two or more determinations on the same sample
Replicates
describes the reproducibility of measurements.
Precision
an element of a data set is the absolute difference between that element and a given point.
Absolute Deviation
is the average of the absolute deviations and is a summary statistic of statistical dispersion or variability.
Average absolute deviation
a measure of the dispersion of a collection of numbers
Standard Deviation
a measure of statistical dispersion
Variance
a normalized measure of dispersion of a probability distribution.
Coefficient of Variation (CV)
the closeness of the measurement to the true or accepted value.
Accuracy
Occasional error that obviously differs significantly from the rest of the results
Outlier
Described by the standard deviation, the variance and the coefficient of variation
Precision
Described by the absolute and relative error.
Accuracy
the absolute error corrected for the size of the measurement or expressed as the fraction, %, or parts-per-thousand (ppt) of the true value
Relative Error (Er)
- the difference between the experimental value and the true value.
Absolute Error (E)
failure to calibrate, degradation of parts in the instrument, power fluctuations, etc.
Instrument errors
errors due to no ideal physical or chemical behavior completeness and speed of reaction, interfering side reactions, sampling problems
Method errors
occur where measurements require judgment, result from prejudice, color acuity problems
Personal errors
is of the same magnitude, regardless of the size of the measurement.
Constant errors
increases or decreases with increasing or decreasing sample size, respectively.
Proportional errors
Normal or Gaussian Curve NAMED AFTER
Carl Friedrich Gauss
