There are dozens of techniques, each with its advantages and drawbacks. Analysis of the same set of papers is shown in Figure 2, where protocols, to which references are made, are arranged by year. Only a fraction of references points out to the original research paper. Typically, the sources are either specialized protocol books, or companies' protocols. Cold Spring Symp.
Reference is available upon request.
A major source is you, i.e. human inconsistency provoked by the superficial simplicity of the assay. Ten pairs of students, each including at least one Ph.D., were given aliquots of necessary reagents, printed protocols as well as detailed oral explanations of the procedure. Never split a large body of work between you and someone else. If you absolutely have to, be sure to spike the data of both researchers with several reference points. In general, data cannot be compared directly.