Accounting for the dependency between outcomes in a multivariate meta-analysis may or may not improve the precision of effect estimates from a network meta-analysis compared to analysing each outcome separately.
As the primary outcome was prevalence of recurrent NSLBP, minimum sample size of 495 was calculated using Epi Info Stalcalc based on the following parameters: regional prevalence of 13.5 % [ 19], a precision effect of 3%%, a design effect of 1 and 95 % confidence interval.
Blocking is an effective method for reducing systematic variations and increasing the precision of effect estimation when the experimental units are not homogeneous.
A target sample size of at least 850 individuals was determined, assuming a prevalence rate of 25%, a type I error of 0.05, a precision of 5% and a design effect of 3.0, in order to take into account the cluster sampling design [27].
A precision of 10% and a cluster effect of 2 were taken into account for this.
The number of participants satisfied a sample size of 800 pregnant women calculated for the oral sub-study, assuming a prevalence of tooth loss (i.e. at least one tooth lost) of 50%, a precision of 0.05 and a design effect of 2. The procedures of recruitment and participation are detailed in the PROMISE EBF study profile [ 25].
The number of participants satisfied a sample size of 800 pregnant women calculated for the oral sub study, assuming a prevalence of tooth loss (i.e. at least one tooth lost) of 50%, a precision of 0.05 and a design effect of 2. At three weeks post- partum, 635 mothers were re-interviewed in their homes and 593 of their infants were assessed for anthropometric status.
This number satisfied a sample size of 800 pregnant women calculated for the oral sub-study, assuming a prevalence of tooth loss (i.e. at least one tooth lost) of 50%, a precision of 0.05 and a design effect of 2. As this study included several outcomes, the size of the sample was calculated separately for each of them and the largest sample size required was adopted.
From that point on you realize the Actor and Director are in perfect sync, that each scene and each element of each scene is staged for maximum precision of effect.
Blocking is commonly used in design of experiments to reduce systematic variation and increase precision of effect estimation.
