Linearity

Linearity – describes the ability of an analysis to produce data points that are directly proportional to concentration (as concentration increases, the signal increases proportionally); a straight line can be used to illustrate the relationship between points (regression line).

• Indicates how accurate analysis is over the desired range of concentration.
• Regression line is a means of statistical analyzation of the data points as a set; the Y intercept indicates the possible presence of systematic error that must be corrected for. The slope of the regression line indicates the sensitivity of the analysis – the steeper the slope, the more sensitive the method is to slight concentration changes.
• The regression line must also be reported with the correlation coefficient, which indicates the degree of linearity between points. Correlation coefficient (R) is expressed as a value between 0-1, with 1 being a perfectly linear relationship.