variance for stratified sampling

boco books of numbers butter one's bread on both have one's bread butter cardiocytoprotection chaetoceros pseudodichaeta demiflat iridoparesis monopropellant propulsion nascent group parrote radio interception or intelligence analysis post real slip right-and-left selection with arbitrary probability skewed population soldered ohmic contact stipo tainiolite (taeniolite) us -hearted wolf's-bane