The Gold06 SnIa dataset recently released in astro-ph/0611572 consists of five distinct subsets defined by the group or instrument that discovered and analyzed the corresponding data .
These subsets are : the SNLS subset ( 47 SnIa ) , the HST subset ( 30 SnIa ) , the HZSST subset ( 41 SnIa ) , the SCP subset ( 26 SnIa ) and the Low Redshift ( LR ) subset ( 38 SnIa ) .
These subsets sum up to the 182 SnIa of the Gold06 dataset .
We use Monte-Carlo simulations to study the statistical consistency of each one of the above subsets with the full Gold06 dataset .
In particular , we compare the best fit w ( z ) parameters ( w _ { 0 } ,w _ { 1 } ) obtained by subtracting each one of the above subsets from the Gold06 dataset ( subset truncation ) , with the corresponding best fit parameters ( w ^ { r } _ { 0 } ,w ^ { r } _ { 1 } ) obtained by subtracting the same number of randomly selected SnIa from the same redshift range of the Gold06 dataset ( random truncation ) .
We find that the probability for ( w ^ { r } _ { 0 } ,w ^ { r } _ { 1 } ) = ( w _ { 0 } ,w _ { 1 } ) is large for the Gold06 minus SCP ( Gold06-SCP ) truncation but is less than 5 \% for the Gold06-SNLS , Gold06-HZSST and Gold06-HST truncations .
This result implies that the Gold06 dataset is not statistically homogeneous .
By comparing the values of the best fit ( w _ { 0 } ,w _ { 1 } ) for each subset truncation we find that the tension among subsets is such that the SNLS and HST subsets are statistically consistent with each other and ‘ pull ’ towards \Lambda CDM ( w _ { 0 } = -1 ,w _ { 1 } = 0 ) while the HZSST subset is statistically distinct and strongly ‘ pulls ’ towards a varying w ( z ) crossing the line w = -1 from below ( w _ { 0 } < -1 ,w _ { 1 } > 0 ) .
We also isolate six SnIa that are mostly responsible for this behavior of the HZSST subset .