In the absence of studies involving a direct comparison, an indirect comparison can provide useful evidence.
These comparisons allowed an indirect comparison between TDF/FTC and ZDV/3TC at 48 weeks, which also did not report significant differences in the same outcome at 48 weeks.
Unfortunately, with the data available and the lack of compliance with the assumptions of transitivity and homogeneity, it was only possible to make an indirect comparison for just one of the outcomes studied.
We will also advance reasons to anticipate stronger results with direct as opposed to indirect comparison ads.
Our study involves extensions of categorization theory, since both the name issue and the direct versus indirect comparison issue are related to its tenets.
The indirect comparison with the pretest group also shows movement (t = -1.
8,21] Hence, visualizing the direct comparisons available now (trials present) and the indirect comparisons (trials not present) would help researchers know which trials to conduct in future.
A modification of GRADE approach was developed by Higgins and Green  in 2011 where the evaluation of NMA depends on indirect comparisons, contribution of the direct evidence to the NMA pooled estimates, assumption of transitivity, and the disagreement between the direct and indirect estimates.
KEY WORDS: Network meta-analysis, indirect comparison, multiple treatment comparison, mixed treatment comparison
We believe this lack of significance is due in part to the fact that our rotation methodology was successful in randomizing the effects of ownership, but also because the indirect comparisons reduced the effects of counterarguing and source derogations more common in comparative versus noncomparative advertising.
Not only did respondents rate the most informative comparative treatment as significantly more informative than all other test ads, but in every case they agreed more strongly that the sponsor possessed certain attributes when indirect comparisons were included along with greater brand information, even though the comparisons were unrelated to the specific attributes mentioned.
Although indirect comparison
"is still considered a reasonable statistical tool to qualify a comparison of effects that have not yet been investigated head to head," only head-to-head comparison, they concluded, would "fully answer the question of efficacy/safety differences between the new drugs for stroke prevention in AR"