Table 1: Methodological issues most common in each of the six reviewed studies.

Study reviewedMethodological issues

Madsen et al. [21](i) Changing entrance criteria in ecological studies.
(ii) Withholding important results from the final publication.
(iii) Conclusions not generalizable to the US vaccination schedule due to widely different vaccination schedules and different levels of Thimerosal dosing in other countries.

Stehr-Green et al. [22](i) Changing entrance criteria in ecological studies.
(ii) Withholding important results from the final publication.
(iii) Conclusions not generalizable to the US vaccination schedule due to widely different vaccination schedules and different levels of Thimerosal dosing in other countries.

Hviid et al. [23](i) Accounting for “person-years” regarding exposure rather than actual exposure levels.
(ii) Conclusions not generalizable to the US vaccination schedule due to widely different vaccination schedules and different levels of Thimerosal dosing in other countries.

Andrews et al. [24](i) Accounting for “person-years” regarding exposure rather than actual exposure levels.
(ii) Conclusions not generalizable to the US vaccination schedule due to widely different vaccination schedules and different levels of Thimerosal dosing in other countries.

Verstraeten et al. [25](i) Cohort of children too young for followup for an autism diagnosis.
(ii) “Overmatching” phenomena due to too closely matched cases and controls.
(iii) Withholding important results from the final publication.

Price et al. [26](i) “Overmatching” phenomena due to too closely matched cases and controls.
(ii) Withholding important results from the final publication.