We chose to provide our protocol and recipe in volume because we suspect that more people have measuring spoons at home than scales. That said, it is certainly possible to convert a recipe from volume to weight; but each participant would have to make this conversion, separately, for each flour and starter. (This is because the density of each flour varies – so 1 tablespoon of all purpose flour will weigh a different amount than 1 tablespoon of whole wheat flour – and so on, across different grains and perhaps even across different brands of flour.)