CHEM 152 Study Guide - Final Guide: Approximation Error, Standard Deviation
Document Summary
Random (indeterminate) error: limited by precision of measurement tools. Equal probability that will be + or - Precision: ability to reproduce a given result for replicate analysis. Propagation of error: when numbers using have their own uncertainties, take them into account to get the uncertainty in the final quantity. Statistics: calculating the uncertainty in the final quantity (average and standard deviation) Absolute uncertainty: actual error associated with given value. Same units as the number it goes with. Use absolute uncertainty to propagate errors in calculation involving addition or subtraction: etotal = (ex^2 + ey^2)^1/2. Relative uncertainty: absolute error expressed as percentage or fraction of the measurement. Use relative uncertainty to propagate errors in calculation involving multiplication or division: etotal,relative = ((ex/x)^2 + (ey/y)^2)^1/2. Tell us whether there is a statistically significant difference between two results. We have results of two sets of measurements, made using the same method. T calculated = (average 1 - average 2)/ s pooled.
