Figure 2.

Similarity between tested intervention and placebo control intervention for all included studies. Items were rated if applicable to individual studies (N provided in supplemental digital content 3, available at http://links.lww.com/PAIN/B673), with the following possible ratings and corresponding numerical values: yes = 2, probably yes = 1, not reported = 0, probably no = −1, no = −2. Full squares indicate mean and SDs are provided as error bars. The empty square represents the overall mean across all items and studies. N = 198.