Measurement Errors, Sig Figs and Dimensional Analysis Flashcards
Arise from experimental variables that cannot be controlled or determined and affect precision.
Random or indeterminate errors
Occur when instruments or measuring devices are uncalibrated or are calibrated improperly. They have the same effect on all samples. Affects accuracy of results.
Systematic or determinate errors
Caused by nonideal instrument behavior, by faulty calibrations, or by use under inappropriate conditions.
Instrumental Errors
Arise from nonideal chemical or physical behavior of analytical systems.
Method Errors
Result from carelessness, inattention, or personal limitations of the experimenter.
Personal Errors
Independent of the size of the sample being analyzed.
Constant Errors
Decrease or increase in proportion to the size of the sample.
Proportional Errors
Solution contains the solvent and all the reagents in an analysis.
Blank solution
Solution contains the sample, solvent and all the reagents in an analysis.
Analyte
Refers to the collection of all the constituents in the sample.
Matrix
The mean value of a dataset is also called
Average
A sample of about the same size that is carried through an analysis in exactly the same way.
Replicate
The middle value in a set of data that has been arranged in numerical order.
Median
The closeness of results to others obtained in exactly the same way.
Precision
The closeness of a measured value to the true or accepted value and is expressed by the error.
Accuracy
The difference between the measured value and the true value.
Absolute Error
The absolute error divided by the true value.
Relative Error
Occur infrequently and often result from an experimental blunder such as misreading a scale or interpreting a number incorrectly.
Gross Error
An occasional result in replicate measurements that differs significantly from the other results.
Outlier
Measures the systematic error associated with an analysis.
Bias
Systematic errors lead to bias.
Bias caused by rounding
Number Bias
Can be caused by prejudice or bias.
Personal Bias
Aids in the detection of systematic instrument errors.
Calibration