Figure 5: (a) The unreliability graph of cryptotanshinone. (b) The unreliable region estimated around the specification limit of cryptotanshinone in tanshinone extract. Blue dashed lines are the 66.7% β-content, 90% γ-confidence tolerance intervals; the diagonal continuous line is the identity line y = x; the red vertical straight line and the black horizontal dashed line are the API specification limits; the shaded region corresponds to the unreliable region.