Since analytical chemistry is the science of making quantitative measurements, understanding the difference between accuracy and precision is vital. Also, it is important that raw data is manipulated and reported correctly to give a realistic estimate of the uncertainty in a result. Presentation of data in the form of graphs is extremely useful.
Simple data manipulations may only require keeping track of significant figures. More complicated calculations require propagation-of-error methods.
The uncertainity in a result can be categorized into random error and systematic error.
See the statistical formula document for more quantitative descriptions of describing and testing data sets.
See the statistics of sampling document for information about uncertainty involved in sampling.