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  Indian J Med Microbiol
 

Figure 1: An example of a funnel plot showing asymmetry which indicates existence of a publication bias. The diamond at the bottom and the vertical line above it represent the pooled effect of 40 studies (each represented by a circle) included in the analysis. In the absence of publication bias, the dots would be expected to be symmetrically located in an inverted funnel formed by the two diagonals. At the top, where studies with greater precision (or larger sample size) are located, the dots are symmetric; however, in the lower part (studies with less precision or smaller sample size), the dots are all located on the one side. The absence of dots in the left lower part of the funnel area indicates bias against publication of smaller studies with negative results, while smaller positive studies and larger studies in either direction get published. The Egger's test also showed presence of a publication bias with P < 0.001[5]

Figure 1: An example of a funnel plot showing asymmetry which indicates existence of a publication bias. The diamond at the bottom and the vertical line above it represent the pooled effect of 40 studies (each represented by a circle) included in the analysis. In the absence of publication bias, the dots would be expected to be symmetrically located in an inverted funnel formed by the two diagonals. At the top, where studies with greater precision (or larger sample size) are located, the dots are symmetric; however, in the lower part (studies with less precision or smaller sample size), the dots are all located on the one side. The absence of dots in the left lower part of the funnel area indicates bias against publication of smaller studies with negative results, while smaller positive studies and larger studies in either direction get published. The Egger's test also showed presence of a publication bias with <i>P</i> < 0.001<sup>[5]</sup>