A method and apparatus in accordance with the invention which, for any given keyword, generate a semantic keyword cluster of meanings and associated proximity scores. In addition, each state in the state machine may be characterized in terms of distributions of a performance metric associated with the entity. Methods include DNA sequencing, DNA fragment analysis, PCR, SNP analysis, oligonucleotide ligation, amplification, minisequencing, and primer extension. The pedal assemblies remain parallel to a support surface throughout their entire range of motion, as the pedal assemblies travel from their upper position to their lower position.