exposure and outcome, or height and weight, etc.), while both measures in compliance studies relate to the same variable (e.g. B X-rays of the rib cage evaluated by two radiologists or haemoglobin measured by two methods). Consider a situation in which we would like to evaluate the adequacy between hemoglobin measurements (in g/dl) with a hemoglobinometer on the hospital bed and the formal photometric laboratory technique in ten people [Table 3]. The Bland Altman diagram for this data shows the difference between the two methods for each person [Figure 1]. The mean difference between the values is 1.07 g/dl (with a standard deviation of 0.36 g/dL) and the 95% match limits are 0.35 to 1.79.