TABLE 3:

A. GEOSTD² from Interobserver, Intraobserver, and Pooled Data Sets.
	CBV	CBF	MTT
Interobserver
Trial 1 (DS1 v 2 v 3)	1.66	1.68	1.35
Trial 2 (DS4 v 5 v 6)	1.84	1.80	1.31
Average	1.75	1.75	1.34
Intraobserver
CTT1 (DS1 v 4 v 7)	1.56	1.46	1.30
CTT2 (DS2 v 5)	1.29	1.34	1.30
CTT3 (DS3 v 6)	1.47	1.48	1.30
Average	1.58	1.43	1.30
Pooled (DS1–7)	1.72	1.68	1.31

B. GEOSTD² derived from inter-observer, intra-observer and pooled data sets for CTT2 and CTT3.
	CBV	CBF	MTT
Interobserver
Trial 1 (DS2 v 3)	1.46	1.52	1.26
Trial 2 (DS5 v 6)	1.22	1.48	1.36
Average	1.35	1.50	1.31
Intraobserver
Average	1.39	1.41	1.30
Pooled (DS2,3,5,6)	1.38	1.46	1.30

Note.—The “average” GEOSTD² values for inter- and intra-observer data sets were calculated from the mean of the variances of the transformed data. The squares of the geometric standard deviations can be used to calculate the range of measurements which may be expected about any given “true value”. This range can be calculated by dividing and multiplying any given “true value” by the GEOSTD² (see Results section for example).