This is in contrast with our findings, because we used mortality as an end point, but the result indicated that lack of blinding and inadequate allocation concealment might contribute to the exaggerated effect sizes in small trials.
A recent study found that bias associated with the lack of allocation concealment and lack of blinding was restricted to trials using subjectively assessed outcomes.
Another weakness and potential source of bias in the current study is the lack of allocation concealment, that is the nurses knew at the time of recruitment the treatment arm to which women were to be randomised.
Generally speaking, a chief reason for the lack of allocation of public capital resources (e.g., buildings and facilities) to the PPP is that the amount of capital transferred depends upon the value of the single assets, which may not reflect the amount needed for the agreed division of shares.
Another common problem was the lack of allocation concealment, proper blinding, and the reporting of lost cases and dropouts.
121 In general, these non-random allocation methods introduce selection bias and biased estimates of an intervention's effect size, 17 167 228 229 mainly due to the lack of allocation concealment (Item 16b).
These unintended biases include the lack of allocation concealment [i.e. the investigators have no knowledge of the experimental group to which an animal belongs (Fisher et al., 2009)], blinded assessment of outcome and random allocation of subjects to experimental groups (see Bebarta et al., 2003; Macleod et al., 2005; Ransohoff and Gourlay, 2010; Sena et al., 2007; Landis et al., 2012).
Quasi-experimental designs, i.e. studies that lack random allocation of treatments, are a useful alternative as long as the drawbacks of such designs are taken into account.
The GRADE system in particular recommends quality downgrading of evidence from RCTs that lack adequate allocation concealment.
Limitations that might result in downgrading are reasonably clearly defined in GRADE and include lack of allocation concealment, absence of blinding and large losses to follow up.
As would be expected, studies that demonstrated a potential risk of bias in ensuring random sequence generation, posed a similar risk of lack of allocation concealment [ 6, 9, 65, 73].
