Summary
Coagulation activity, expressed as percentage of normal and as clotting time ratio,
was estimated in 220 specimens from patients on long-term anticoagulant treatment
by 3 different coagulation test procedures, i.e. Thrombotest, Simplastin-A and Normotest. The estimates were calculated from the same
determinations.
The distribution of percentage values showed a fairly pronounced deviation from normality.
After logarithmic transformation, the distribution was normalized, the regression
lines between Thrombotest and other tests became parallel, and that between PIVKA-insensitive
systems was shifted to a 45° line. Logarithmic transformation also stabilized the
residual variance. These features make percentage values accessible for treatment
according to the standard methods of bioassay statistics.
Attempts to normalize the distribution of ratio values by various transformations
were unsuccessful. Formal analysis of data revealed a variation in the proportionality
of ratio values with the level of estimated coagulation defect. This may restrict
the usefulness of the ratio approach. Logarithmic transformation partly reduced the
discrepancy.
