His stated goals are to roleback progress back to the 1950 s . I haven ' t heard this . Source ? <| sep |> They are models based upon someone else ' s process , neither is most likely correct for your system . If you pick one program and learn how the numbers from that program relate you your sensory determination of the bitterness of the beer you brew , you will be much further ahead . The IBU measurement is of isomerized alpha acids and not of bitterness perceived by the imbiber . I ' ve had tastings of several beers same style of the same measured IBU values and the tasters could distinguish vast differences in the bitterness of each . <| sep |> 751031 First Order Transporter 1 1 . jpg 702251 Bladvic ' s Rumble Bear 1 1 . jpg