Funnel plot with standardised residuals versus standard errors from meta-analysis of studies on proportions of dentists and dental hygienists with a positive attitude towards extended scope of dental hygiene practice . A; A&O(d) A&O(dh), Abelsen & Olsen26; B, Blue et al.24; G&R, Gordon & Rayner57; H(d) H(dh), Hopcraft et al.25; L, Lambert et al.59; M&C, Moffat & Coates60; M&H, Murtomaa & Haugejorden61; S, Sgan-Cohen et al.62; d, dentists; dh, dental hygienists.