The total number of households to be selected from each of the three primary strata considered the total number of households in each of the primary strata, sample size and overall total number of households at district level.
In each stratum, samples were selected independently through a two-stage selection process.
Using this scheme plots are allocated according to n h ~ N h S h, where h indexes strata, n h represents stratum sample size and N h and S h represent stratum population size and standard deviation of timber volume respectively (Cochran 1977).
Eventually, using a stratified (by Swiss canton) random sampling approach, 2,285 dairy farms (with stratum sample sizes proportional to the cantonal cattle population) was drawn from the available sampling frame using computer-generated random numbers [ 10].
Analyses were conducted in STATA 7.0 STATA Corp , College Station, TX) by using svy methods and adjusting for sample strata, primary sampling units, and population weights.
Eleven of these thirteen SNPs were recovered from the Classic Christian (1000 1450 years BP) and Napatan (2400 2900 years BP) sample strata and 5 SNPs (including the 2 vrs1.a1 clade specific SNPs) were recovered from the Pre-Meroitic (1900 2000 years BP) stratum sample (Figure S3).
This stratum sampling weight was defined as the ratio between the population stratum size and the observed sample stratum size.
The stratum sampling rates were specified as being equal to the actual percentages observed in the arthritis with anemia cohort.
For each species (sheep and goat), the stratum sample sizes determination was carried out using the formula by Bennett et al. [ 21] implemented within the ProMESA software program for statistical sampling in animal populations [ 22].
