Drug Testing Laboratory Practice Test

Linearity in calibration curves is about how well the signal varies in proportion to concentration. The correlation coefficient is used to quantify that linear relationship because it directly measures how tightly the data points fit along a straight line, with values near ±1 indicating a strong linear relationship and thus excellent linearity. A high correlation coefficient means changes in concentration map predictably to changes in response, which is what you want for a reliable calibration. The slope tells you the sensitivity (how much the signal changes per unit concentration) but not how well the data align to a straight line. Peak height is simply the signal amplitude and doesn’t by itself reflect how linear the response is. R^2 (the square of the correlation coefficient) is related and often reported, but the fundamental measure of linearity is the correlation coefficient itself.