The APA Style guideline on how to format meta-analysis references changed from the fifth to the sixth edition of the Publication Manual. Because of unintended consequences of that change, we have reverted to the fifth edition format for meta-analysis references as of the most recent printing of the Manual.
The fifth edition style rule had three parts:
- Include all meta-analysis references in the reference list and not in a separate appendix.
- Precede each meta-analysis reference in the reference list with an asterisk.
- Add the following statement before the first reference list entry: “References marked with an asterisk indicate studies included in the meta-analysis.” (APA Publication Manual, 5th ed., section 4.05, p. 222)
Reference lists that include meta-analysis references are sometimes quite long. To conserve pages, in the sixth edition of the Publication Manual a new rule was introduced that applied only to articles with more than 50 meta-analysis references. (The fifth edition style rule for formatting meta-analysis continued to apply to those articles with 50 or fewer meta-analysis references.) These are the new rules that applied to longer lists of meta-analysis references:
- Place meta-analysis references in a separate list and submit that list as supplemental material, which will appear online but not with the print or online version of the article itself.
- If a meta-analysis reference is mentioned in the text, it should appear both in the reference list and in the supplemental material. (APA Publication Manual, 6th ed., section 4.05, p. 183)
Several years of experience with the new rule for longer lists of meta-analysis references has revealed two shortcomings. First, abstracting and indexing services pick up references in the article itself but not those from online supplemental materials. The new rule skews citation statistics and disadvantages authors of meta-analysis references in those longer lists. Second, emerging best practices for what types of material should be included in the core article include a stipulation that the core article include all references.
As of September 2012, all new printings of the sixth edition of the APA Publication Manual will contain the same style guidance on meta-analysis references as appeared in the fifth edition. We regret the inevitable confusion caused by changing a style rule between printings, but in this case, making the change seemed better than the alternative.