This defaults to 1 but can be changed using this function with knock-on effects for how < values are treated when maps are optimized or relaxed and the way stress is calculated, see details.


dilutionStepsize(map) <- value



The acmap object from which to get or set the dilution stepsize


The dilution stepsize value to set


Antigenic cartography was originally developed for HI titers which typically follow a 2-fold dilution series starting from 1/10, then 1/20, 1/40 etc. This represents a "dilution stepsize" of 1 when converted to the log2 scale. When no inhibition was recorded at the highest dilution, the value is typically recorded as <10 but the optimization regime effectively treats this as a <=5, the rationale being that, had the dilution series been continued to higher concentrations, the next lowest titer would have been a 5. Over time the method has also been applied to other neutralization assays that sometimes have a continuous read out with a lower end, in these cases a <10 really means a <10 since any other values like 9.8 or 7.62 would also be possible. To indicate these continuous cases, you can specify the dilution stepsize as 0. Equally, if the dilution regime followed a different pattern, you can also set that here.

See also

Other map attribute functions: acmapAttributes, mapName(), titerTableLayers(), titerTable()