We examine whether a comparison between w CDM and R _ { h } = ct using merged Type Ia SN catalogs produces results consistent with those based on a single homogeneous sample .
Using the Betoule et al . [ 1 ] joint lightcurve analysis ( JLA ) of a combined sample of 613 events from SNLS and SDSS-II , we estimate the parameters of the two models and compare them .
We find that the improved statistics can alter the model selection in some cases , but not others .
In addition , based on the model fits , we find that there appears to be a lingering systematic offset of \sim 0.04 – 0.08 mag between the SNLS and SDSS-II sources , in spite of the cross-calibration in the JLA .
Treating w CDM , \Lambda CDM and R _ { h } = ct as separate models , we find in an unbiased pairwise statistical comparison that the Bayes Information Criterion ( BIC ) favors the R _ { h } = ct Universe with a likelihood of 82.8 \% versus 17.2 \% for w CDM , but the ratio of likelihoods is reversed ( 16.2 \% versus 83.8 \% ) when w _ { de } = -1 ( i.e. , \Lambda CDM ) and strongly reversed ( 1.0 \% versus 99.0 \% ) if in addition k = 0 ( i.e. , flat \Lambda CDM ) .
We point out , however , that the value of k is a measure of the net energy ( kinetic plus gravitational ) in the Universe and is not constrained theoretically , though some models of inflation would drive k \rightarrow 0 due to an expansion-enforced dilution .
Since we here consider only the basic \Lambda CDM model , the value of k needs to be measured and , therefore , the pre-assumption of flatness introduces a significant bias into the BIC .