Table 2

Effect of the number of measurements of the reference technique on the percentage error

Measurements for the reference technique, number

Ref precision, ± percentage

Study precision, ± percentage

PE, ± percentage

± 30% fulfilled

1

18

29

34

No

2

12

29

32

No

3

10

29

31

No

4

9

29

30

Yes

5

8

29

30

Yes

6

7

29

30

Yes

7

7

29

30

Yes

8

6

29

30

Yes

'Measurements for the reference technique' means the number of measurements averaged for the reference technique. 'Ref precision' is the precision for the reference technique according to the number of averaged measurements, 'study precision' is the precision of the studied technique as measured by the worked example, and PE is the percentage error for the Bland-Altman plot for the reference technique minus the studied technique. The '± 30% fulfilled' column shows whether the PE would be accepted according to a cutoff of 30%.

Cecconi et al. Critical Care 2009 13:201   doi:10.1186/cc7129